History Fridge / Undertale

* [[FridgeHorror/{{Undertale}} Fridge Horror]]

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[[folder:FridgeBrilliance]]
[[AC:Frisk and Chara]]
* When naming your character, the game specifically asks you to "Name the fallen human". Obviously this is referring to the child you control, and how they ''fell'' down the chasm in the game's intro, right? Nope. The name you enter at the beginning of the game turns out to be the name of the First Child, who had passed away, or '''''fallen''''' due to an illness.
** "Fallen" also relates to the whole Delta Rune prophecy mentioned further down the page. The child appears angelic, but in the end is actually demonic, and ends up destroying the world.
** The angelic appearance and the 'fallen' nature of the First Child actually somewhat reflect Lucifer (aka Satan/The Devil/Beelzebub) from Christian mythology. He was an angel that rebelled and fell from heaven, similar to how the First Child (who, on the surface, would likely be seen as an outsider due to their sadistic mindset) literally '''''fell''''' from the surface. This is backed up by the fact that Lucifer is seen as a tempter and a manipulator, much in the same way that both Flowey and The Fallen Child use the promise of EXP and LV (more power in exchange for acts of evil) to tempt the player into bringing about the death and destruction they seek.
** This is reflected in their shirts as well. Both the First Child and Asriel wear green. Each have symbolized both hope, and Satan. The Fallen Child first symbolizes hope, then Satan in a Genocide Route. Asriel first symbolizes Satan, then hope.
*** A more optimistic way of looking at the Fallen Child's title of "Fallen Child" is simply that it was given to them because they fell down the mountain.
** The inherent twistiness of the phrase lends to the incredible double subversion: you ''are'' naming the fallen human, you ''are'' naming the child in the opening, but who says you are naming the PlayerCharacter?
* When you first meet Toriel, she introduces herself by saying "greetings". Who else introduces themself like that? Chara, of course!
* The fact that the player character develops a separate, homicidal personality is actually even more of Undertale's meta-commentary on games in general. Certain stereotypes aside, it's likely a player who encounters the Fallen Child isn't actually a killer in real life, or even wants to be; they only are killing everyone in-game just to see how deep the rabbit hole goes, or are probably just fanatical at LevelGrinding. To them, the character they're controlling is a ''different person''. So, that's what the game [[LiteralGenie gives you]]; a VillainProtagonist completely at peace with the idea of killing every living thing in order for a player to see what happens. Chara even refers to themself in the context of being a player character in a game, as a "demon" that is summoned when their name is called (i.e., when you name them at the beginning of any game) and claiming "Time after time, I will appear. And, with your help. We will eradicate the enemy and become strong. HP. ATK. DEF. GOLD. EXP. LV. Every time a number increases, that feeling... That's me." Hands up; who here thinks such an [[CardCarryingVillain individual]] would [[TheStarscream react badly]] to finally being told "no?" Karma can be a tough old broad, can't she?
** This could be taken a step further, when taking a certain theory into account. The separate character is the first fallen child (or their mindset, rather). Your character would never do this, but the original child, overtaken by grief and emotion, would.
* All of the human [=SOUL=]s have a certain color associated with them, and the player character's SOUL is colored red. The PC is also the only human to survive their journey through the underground. When dealing with the light spectrum, red is the color with the longest wavelength — that is, to say, [[VideoGame/KingdomHearts358DaysOver2 out of all the colors, red is the one that travels the farthest.]]

[[AC:Flowey and Asriel]]
* Flowey:
** Flowey's final form has a load of attacks, but the SOUL WARNING attacks are all different weapons you can equip during the game. This is because he's using the souls of the other six children, who used these weapons before dying.
*** Additionally, the reason for the SOUL WARNING's is because the SOUL's ''themselves'' are warning you about Flowey using them.
** He also taunts you to call out to mom while making Toriel's face. Toriel was the Fallen's adoptive mother and the Fallen is connected to the player character (very loosely in a neutral run admittedly, but still).
*** She was also Flowey's, or rather Asriel's, biological mother. The words he taunts you with are ''exactly'' what he said when he first woke up in that form and cried out for his parents — although you'd only know that if you did a No Mercy route.
*** Toriel also [[MyBelovedSmother acted motherly towards Frisk]]. While it wasn't to quite the same extent as Asriel and Chara, of course, Frisk ''does'' have the option of calling her "Mom" at one point.
*** Alternatively, this could be interpreted as Asriel's true face, which happens to look like his mom. Maybe not so much like shapeshifting and more like reverting to an old face. Flowey does this at the end of a Genocide run when he begs Frisk/Chara for mercy, too.
** Flowey the Flower is kind of an uninspired name. Looks like Asriel inherited his father's GiverOfLameNames trait.
** At first, Flowey's tendency to say things like "Howdy!" and "golly" seem to be there only to enforce his FauxAffablyEvil act until you meet Asgore, who speaks in a similar manner, and learn that he's Asriel/Flowey's father.
** Flowey and Asgore also make almost the exact same expression when Toriel knocks them away from you with her flame magic.
** In the Neutral ending, Flowey recovers the power of Save and Load from you... by erasing your save file and making it his own.
*** Even more, he's able to use up to six different save states. Six, as in the number of human [=SOULs=] he currently has.
** In the Neutral end, Flowey declares that after killing you, he'll use your soul and the six human souls Asgore gathered to become God and rule over/destroy everyone and everything. He's perfectly capable of killing you with minimal effort... so why doesn't he enact his plan, instead opting to reload your save and kill you more? Because, as shown in the Pacifist ending, that's not what he really wants to do. Being Asriel, what he really wants is to be able to play with the player again and again, forever... which is what he's doing by reloading whenever you die.
* If you kill Flowey during a Neutral run, on subsequent runs through the game, he doesn't appear throughout the game until the end. This could be interpreted as a permadeath of sorts, except that he shows up anyway to destroy Asgore's SOUL after the latter sacrifices himself. So what's going on? One of the possible endgame conversations with Flowey (in a run where you have ''not'' previously killed him) gives a possible answer: Flowey mentions that Sans caused him his "fair share of resets", but if you talk to Sans, he's never seen Flowey, and thinks his brother's conversations with a flower involved an Echo Flower. So Flowey's deliberately been avoiding Sans because Sans is a danger to him... and after you killed him in the previous ending, he's now started avoiding ''you'' for the same reason.
* After leaving Toriel, Flowey did tell you that he was prince of this world. In addition, he might not have been [[ExactWords technically lying about not planning to commit regicide, at least at the time]]; If you spare everyone you meet in the ruins, including Toriel, his dialogue implies that he expects you to cave in and kill if you meet "a relentless killer" that can't be spared. Asgore, though not a relentless killer, ''does'' take away your ability to spare him at the start of the fight. Initially, the fight seems to follow Flowey's philosophy of "kill or be killed", since you're forced to fight him. Flowey was probably intending for you to kill him off, and only does so himself if you choose to spare Asgore at the end.
* It's no coincidence that the name Asriel sounds a lot like Azrael, the Archangel of Death in Hebrew and Islamic lore. According to Wikipedia, Azrael (or Azriel, as the name is sometimes spelled), has four faces and four thousand wings, and his whole body consists of eyes and tongues, the number of which corresponds to the number of people inhabiting the Earth. (Which sounds a lot like Flowey/Asriel's final form in the Neutral Ending.) He (Azrael) will be the last to die, recording and erasing constantly in a large book the names of men at birth and death, respectively. (Sounds a lot like Flowey/Asriel's ability to overwrite Save Data and manipulate life and death.) Sure looks like the game writers might have done their homework in researching the mystic symbolism for this game....
* Asriel's final form looks a bit abstract and attacks with rainbows, stars, a huge laser, and [[CallingYourAttacks they all have attack names.]] [[NotGrowingUpSucks Considering his age when he died, it starts to make sense that his ultimate form is closer to what an 8-year-old would see in a Saturday morning cartoon villain and makes it all the more tragic.]]
* Omega/Photoshop Flowey himself is an extradimensional form of this. You have been playing the entire game in a pixelated, low-color, low-detail environment. That's not just there for the aesthetic, although it does contribute in a big way to the nostalgia factor. Now, when you meet Flowey in this form, he is anti-aliased, full-color, full-detail (as much as the game engine will allow), transcending the laws of physics and nature within the game. Since we humans live our entire lives in our own universe, with objects and beings with their own forms, shapes, sizes, and colors, imagine how it would feel seeing [[AlienGeometries something or someone that transcends our laws of physics and nature.]]
* During the battle with Flowey's final form, Flowey regains the power to save and load, meaning he's the only boss in the game that could actually ''kill you'' for good if he felt like it… but he doesn't. He keeps bringing you back with that power so he can keep killing you. Why? He's been ''unbelievably bored'' with the Underground for goodness knows how long… and finding out how many different ways he can kill you is the first exciting thing to happen to him in ages. The fact his ''true'' form is a child makes this make even more sense: Flowey is a child who'd gotten bored with his entire toy box and is now obsessed with his brand new toy: you. Of course, this comes back to seriously bite him in the butt, but it fits the character.
* If you lose to Photoshop Flowey, you hear Asgore's voice telling you that "this is all just a bad dream", followed by Flowey's voice informing you that "you are ''never'' waking up!" If you go on to the True Pacifist route later, you learn that unlike the standard GameOver quotes, which ''are'' spoken by Asgore in the tape of the Fallen Child's death, the "bad dream" line is never spoken by Asgore at any point in the game. This gives you [[RewatchBonus a big hint that said line is Flowey impersonating Asgore]].
* It's been mentioned elsewhere that Flowey's FinalBoss form resembles both the DT extraction machine and Sans's Gaster Blasters. Both of these are used in his fight: Determination allows him to save and load, and occasionally, he'll fire a beam in a similar fashion to the Blasters.
* Flowey's [[VillainousBreakdown screaming tantrum]] when the human [=SOULs=] rebel against him makes a lot of sense when you remember that he's basically a scared little boy given almost god-like power over the world. In that sense, you can read his dialogue as being like that of a child who's had his toys torn away from him, because that is in a sense what has actually transpired.
* It's been said in the past that the best type of villain is [[VillainHasAPoint one who talks sense]], [[WellIntentionedExtremist who gives good valid reasons for doing what he does]]. Asriel is that condensed down to its purest form. Yes, he wants to kill everyone, but afterward, he plans to use all the energy from every monster and human on earth to remake the world so that nobody will have to leave anyone else ever again. No more death, or loss, his family and everyone else's will remain whole forever. He gets his sibling back to boot and his parents are happy again. Honestly, if his plan didn't involve committing genocide to work, then you'd probably be expected to root for him, not the player character.
* Asriel's name is a combination of his parents' names, Asgore and Toriel... because Asgore is terrible at naming things. It was probably the only thing he could come up with. (Another rationalization would be that Asgore just followed the Germanic naming convention of combining the parents' names to name the child. Considering his theme music has a German title, that's not so implausible.)
** [[SignificantAnagram Asriel's full name, "Asriel Dreemurr", can also be read as an anagram for "Serial Murderer"]] (which is a fitting thing to call him after he dies and turns into [[BigBad Flowey]]).
* Asriel's final desparate plea to allow him to win during the final battle of a Pacifist Run. Though he uses the name given, some of the things he says could be perceived as being directed towards the player. If the player wins the encounter, that's it. The game is over. This is similar to what Flowey said before consuming everyone's souls just moments ago. Given that Flowey and Asriel are the same person, this is the same idea coming across in two distinctly different ways: '''''If you win, you stop playing the game.''''' Though many of the characters form some sort of attachment to the player's character, it's almost as if Asriel/Flowey have formed an actual attachment to the '''player themself''', and desperately want the player to keep playing the game for that reason.
-->'''Flowey''': "WHY am I still doing this? Don't you get it? This is all '''''just a GAME'''''. If you leave the underground satisfied, you'll "win" '''''the game'''''. If you '''''"win"''''', you won't want to '''''"play"''''' with me anymore. And what would I do then?"
-->'''Asriel''': "I'm not ready for this to end. I'm not ready for '''''you''''' to leave. I'm not ready to say goodbye to someone '''''like you''''' again.... '''''JUST LET ME WIN!!!'''''"
* If you spare Flowey at the end of a Neutral Run, the encounter will end with him Fleeing, complete with the message "*Flowey ran away." Flee is a Mercy option. You've shown Flowey once and for all that it's not kill or be killed by making him choose an option from the Mercy menu while refusing to pick the Fight option.
* The first refusal to die while fighting Asriel after he transforms has him gloating about your immortality, your hold still decreasing every time you die, your friends remembering you less, being trapped in a world where no one remembers you forever, and how your determination will be your downfall. He isn't gloating. [[FreudianSlip He's venting.]]
* Why didn't Flowey act sociopathic until later on? Because people who once had the capacity for empathy, only to lose it, retain their sense of morality. Why did he snap anyway? He himself admitted to being in a permanent state of fragmentation near the end of the Genocide Route. Not to mention the discovery of saving and loading was bound to get boring after a while with no emotions.
* Despite howdy being, you know, a pleasant greeting, the circumstances are never pleasant in which it's used. Flowey always uses it, but then he's always scheming something, and Papyrus uses it once, but only when he's being manipulated by Flowey. Asriel uses it talking to Chara, but that very same conversation leads to the plan that ends in both of their deaths. The only other person who uses it is Asgore, and that's before you two battle for the fate of the underground. And, crossing into Fridge Horror, that's when it hit me: the phrase "howdy" is only ever used by a character when either them or the person they're addressing is going to die.
* When you abort a Genocide run, Flowey is annoyed that "Chara" quit after getting so close to succeeding, but decides they must want to try everything else out first and tells them he'll be waiting when they're done messing around. People have pointed out that he still says this even if you reset at the screen where you can ''kill him'' in the Genocide run — after he (rightfully) got scared that Chara would kill him, betrayed them by running off to Asgore, and broke down into tears with Chara advancing on them to kill. Why on earth would he react to the reset with such nonchalance when he was so obviously scared of Chara? Well, we know Chara used to make creepy faces for Asriel's entertainment, and we know that Asriel ''adored'' Chara and has a huge blindspot for them even as the soulless Flowey. From Flowey's perspective, Chara made a creepy face at him, but crucially ''never actually attacked him;'' so when they reset without actually attacking or killing him, all he could assume is that that's all it was — oh, it was just Chara making a face to scare him like they used to, golly, it's so embarrassing that he still falls for it. Now that he thinks Chara isn't really out to kill him, he's exasperated that they pulled a joke like that at such a critical point, but he accepts it as their type of humor. No, most people wouldn't react to Chara the same after that; but both Flowey and Chara are sadistic soulless killers at this point, so ''Flowey'' would think that it's not a big deal.
* Why is Asriel the only one to ask why Frisk went to the mountain to begin with? Because Chara admitted their own reason to Asriel, even if Asgore and Toriel were not aware of it. For all we know, when Asriel says "everyone" knows the mountain as a place of no return, he might only mean the humans, and monsters might not even be aware how the humans think of their home.
* Flowey is the only monster in the Underground capable of bringing even a Pacifist player's HP to 1, and he takes several swipes by Chara to destroy. This is because Flowey is not a monster or a human and thus not subjected to the same rules. He's more of a Amalgamate without a SOUL, or a flower possessed by a monster rather than a monster himself. In Undertale monsters are so weak to humans because they possess almost no actual physical matter, being made up of magic, while humans are made up of physical matter almost entirely. As such, Flowey is significantly more powerful and takes more to kill because he's made up of much more physical matter than any other being in the Underground besides the player themself.

[[AC:Ruins / Toriel]]
* "Three out of four grey rocks recommend that you push them." Literally. You have to ask the fourth one to move.
* Toriel, a very motherly character, has the track "Fallen Down" for her non-battle theme. Guess what game the instruments in that song come from? ''VideoGame/EarthBound'', aka '''MOTHER 2'''.
** If you interpret Frisk as having parents (which some interpretations do) before falling down, then Toriel is '''Mother (number) 2'''.
* Check the tree in front of Toriel's house: "Every time this old tree grows leaves, they fall right off." After Toriel welcomes you inside and you take a nap, you find Toriel again to ask her how to get back home.
* The song Heartache, which plays during Toriel's battle, isn't dramatic for no reason or just to reflect Toriel's emotions. It's your first real battle and the moment that you choose what type of person you're going to be in the game.
* The song "Home" that plays in Toriel's house has the soothing acoustic melody you'd expect of a safe place. But in spite of its initial impression, the song has noticeable flaws once you listen closely: the chords start to stumble over themselves, the tempo keeps wavering constantly, and the song almost starts breaking down entirely before returning to the original beat. This represents how, despite how much Toriel wants you to be happy living with her, it's not where you belong.
* You have the option to call Toriel "Mom". Well, she is the Fallen's adoptive mother.
* Why are the Ruins' puzzles activated in the beginning? Because the field of flowers the player character landed on is the Fallen Child's grave, and Toriel doesn't want people messing with it. It's the same reason she's there tending the flowers if you spare her and why Asriel is there in the PlayableEpilogue.
* Toriel seems weaker than Asgore, with simpler attack patterns and no flashy weapons, but she knocks him away easily in the True Pacifist ending. Why is that? Because she was treating you with kid gloves to scare you back into staying with her. We honestly can't gauge her real capabilities because, unlike Asgore, who is fighting to kill, she's only ever seen fighting to frighten. She may be ''stronger'' than him.
** Even better, CHECK the stats in the combat menu, and it reveals both characters have the same stats: 80 ATK, 80 DEF. Way more than any of the other bosses in the game (Undyne's ATK is 7). Yet Asgore also does only a little more damage than the previous bosses — they were ''both'' holding back.
** Toriel weakens her attacks and deliberately misses you when your HP gets too low, which makes sense, since she's not fighting to kill. While Asgore's attacks are always intense, [[HPToOne he never finishes you off unless you have 1 HP]]. [[LastChanceHitPoint Even if the next hit could kill you, he holds back until there is nothing else he can do.]]
** Look carefully at how Toriel and Asgore attack as lost souls. At first, it just looks like one of Asgore's attacks, then a second hand comes in and does the same attack at the same magnitude. Toriel used a smaller version of that attack during her fight, and since she isn't holding back (as much) now, they're both doing the same attack at the same time, their power at the same level.
* Why are Toriel's socks considered scandalous? Because she's a BarefootCartoonAnimal. Socks in general seem to be an "inappropriate" article of clothing in this universe. If you hum with Shyren, monsters show up to make it a concert and toss their socks at you.
* Why is Toriel so afraid that Frisk will get hurt and is so overprotective of them? Because she had lost two children ''in one night'' to murderous "people" with confused morals.
** If you backtrack after being guided by Toriel, you'll discover that the spike puzzle actually isn't dangerous — they just act as walls. However, Toriel has a perfectly good reason to be worried about things that ''seem'' harmless, because the Fallen Child died after (intentionally) poisoning themself by eating buttercups.
* Toriel says she wants you to prove that you're strong enough to survive before engaging the battle, yet even if you've been treating the game like a typical RPG and killing every encounter thus far (but not going full Genocide in the sense that you're deliberately seeking out everything), bringing yourself to hurt her isn't easy. She's not just testing if you're strong enough physically, but ''mentally'' as well — all the fighting power and ability in the world won't help you if you're not willing to make use of it, so she wants to know if you'd be willing to fight someone who's been nothing but kind to you if your life depended on it. If you can kill someone under those circumstances, then you can take on anyone, so she knows she won't have to worry about you.
** It seems to be a major reason she lets you go even if you simply stand your ground and don't fight back. By refusing to back down, you've shown a different kind of strength — the resolve to stand up and face danger head-on, but also be able to find a peaceful solution while being attacked.
* Another sign that Toriel is holding back in her fight is in her attack that opens with her hand going across the soul box with fire trailing it. If the hand hits the child's soul (implying that Toriel physically hit the child), the attack ''immediately'' stops.
* Toriel keeps a chocolate bar in her fridge. While at first, it looks like Fridge Horror [[AccidentalPun (no pun intended)]] because chocolate is poisonous not just to dogs, but also to ''goats'', it goes back to Fridge Brilliance because it was for Chara, and it was [[TrademarkFavoriteFood their favorite.]]
* A Froggit admits that everyone in the Ruins is intimidated by Toriel, which seems odd, since she's perfectly friendly and welcoming. This comment makes a ''lot'' more sense when you find out that Toriel used to be queen of the Underground (and most monsters likely still consider her to be such, even if she left the castle). While most of the Underground isn't sure where Toriel went after she left Asgore, everyone in the Ruins would know ''exactly'' who she is. Wouldn't ''you'' be a bit intimidated if your country's ruler suddenly moved in next door?
* On paper, Toriel has very high stats -- AT and DF both 80, making her equal to Asgore, who is a FinalBoss, and she is a boss monster as well, meaning she has a stronger SOUL than other monsters. So since you fight her in the beginning area, with your highest possible stats still extremely low and only having access to the worst equipment of the game, it SHOULD be a near-impossible boss fight where she absolutely wipes the floor with you each time. Instead, she is a starter boss fight, with monsters that have lower stats than her proving to be more difficult fights. So why does she do so little damage and go down so easily, even at a low level and getting one-shotted when you bring down her health to a third? A book in Snowdin explains it: ''"Because they are made of magic, monsters' bodies are attuned to their SOUL. If a monster doesn't want to fight, its defenses will weaken. And the crueler the intentions of our enemies, the more their attacks will hurt us. Therefore, if a being with a powerful SOUL struck with the desire to kill..."'' Because Toriel DOESN'T want to fight the protagonist, she's FORCING herself to do it in hopes that she'll either scare them into backing down and staying safe with her, or if they really want to leave, [[SuicideByCop force them to kill her]] and in doing so [[ToughLove harden their heart]] enough to be willing to kill to survive up against the monsters out there who WILL want to kill them, like Asgore, [[CruelToBeKind so they might be able to escape the Underground with their life]]. Her attacks do much less damage than they should because she doesn't actually want to hurt them and isn't fighting anywhere near full strength, and ''their'' attacks do more damage to her than they should (even with no EXP gained) because her DF is lowered since deep down she doesn't want to fight and hurt you. If you're on a Genocide run, this causes her to die in one hit despite her high DF stat, from a combination of her unwillingness to hurt the protagonist and their willingness to kill - when weaker monsters you'll fight after her with much lower DF and you at higher LV require more hits since they want to fight, which speaks more to just how reluctant Toriel was to fight you with such high DF. On any other run, the longer the fight goes on, the more her will falters - allowing the protagonist to convince her to accept their mercy, or if they're fighting back, causing her to lose the will to keep fighting at all and die from the next hit. Adding to this, it's implied that Asgore is also holding back somewhat and we haven't yet seen the ''true'' potential of boss monsters like him and Asgore fighting at full strength and willingness to hurt. TLDR: The human was '''''very''''' lucky the goats are so soft-hearted.

[[AC:Snowdin / Sans and Papyrus]]
* Sans and Papyrus:
** They're named after typefaces (Comic Sans and... Papyrus) that get a lot of hate in the design world for being overused. Similarly, the characters get little respect when they show up (they're upset at their limited appearance in the demo, and the narrator shuts them down in the Steam Greenlight trailer). Their skeletal appearance might also be a VisualPun of the "overuse" of their namesakes. Yet, by virtue of their enigmatic nature, the characters already have a fan following.
** Their personalities also seem to be based on the common perceptions of those typefaces. Comic Sans is used when businesses try to appear friendly (but end up looking lazy) and Papyrus is used to make something seem more meaningful and important than it really is. The characters themselves have more depth than that, but those aren't bad summations of who they are.
*** The EasterEgg character, W.D. Gaster, speaks in Wingdings, a font consisting entirely of random symbols. It's a pain to read unless you're dedicated enough to learn (made only slightly easier by the fact that Gaster only uses Wingdings 1 in all uppercase), and only exists because it used to be the most efficient way to include those symbols in word processors. Gaster mysteriously disappeared from both reality and memory, but was the royal scientist and designer of the Core before then, fulfilling his font's characteristics as hard-to-understand and a once-useful relic of a bygone age.
** Their personalities also extend to the typography of their speech — the excessively enthusiastic Papyrus is all capital letters and exclamation marks. Even if he means well, he ''is'' trying a little too hard. Sans, on the other hand, is too lazy to even capitalize properly (except in certain… instances).
** Even their physical appearance resembles their namesakes: a short, stocky, casual-looking buddy, and a tall fellow trying to look important.
** Also, Papyrus tends to be considered [[NoIndoorVoice TOO LOUD.]]
** Not to mention Sans… is a comic. And in a No Mercy run, he loses all his comedic intent and his font changes to 8bitoperator. On top of that, it's a sans serif font, which is also a semi-homophone for 'seraph,' an angelic rank. What are angels often depicted doing? ''Opposing the demonic forces of evil.''
*** Why is Papyrus "Papyrus" but Sans is just "Sans"? [[LetsGetDangerous Because there's nothing "Comic" about him.]]
** Undyne mentions that Papyrus has everything it takes to be a member of the Royal Guard, but refuses him on account on him being 'too nice'. It shows in his stats, too — Papyrus has 8 ATK and 2 DEF; the only boss monsters he's weaker than on a Pacifist run are Toriel (who has 80 ATK and DEF, but is holding back) and Asgore (who also has 80 ATK and DEF, but is ''also'' holding back (albeit not as much as Toriel) and can be talked down into holding back further). Undyne herself has 7 ATK and a DEF score of zero, and Mettaton EX has 8 ATK and 1 DEF.
** During Papyrus' boss fight, he hypes up his special attack when it's actually doing nothing but waiting around while Papyrus yells at a dog until he finishes. In Sans' boss fight, the special attack is also hyped up when it's actually a whole turn of literally doing nothing in an attempt to stall you, but you really have to wait around until he falls asleep to scroll over to the FIGHT button.
*** The game strongly implies that Papyrus learned fighting properly from Undyne and that Sans learned some fighting from Papyrus. Considering what a nightmare Sans attack BEFORE his special attack is and that Papyrus complains that his special attack got stolen by the dog, it might well be that if not for the dog, players could have been ''decimated'' if Papyrus had not lost his bones.
** On the No Mercy path, when Papyrus dies, he asks the player to keep moving forward out of the hope that they'll change their ways. Meanwhile, Sans makes an effort to stop the player in their tracks. They're orange and blue, respectively. What do orange and blue attacks do?
** Ironically, while Papyrus' CHECK text in the No Mercy route describes him as "forgettable", out of any other monster you can kill, Papyrus gets mentioned the most. Undyne drops all of her [[LargeHam energetic]] [[HotBlooded theatrics]] and coldly promises to kill you. Sans, meanwhile, drops out of the game entirely should you kill Papyrus until the very end of the game, where he delivers a much more scathing judgement than he would even if you'd killed every monster ''except for'' Papyrus. (He'll also refuse to make fun of your level if you keep reloading before the judgement, and won't congratulate you for any self-imposed challenges in the end-of-game phone call.)
-->'''Undyne:''' What did you ''DO TO HIM''?
-->'''Sans:''' ''"[[YouBastard You dirty brother killer.]]"'', or ''"[[WhatTheHellPlayer Then why'd you kill my brother?]]"'', depending on how you answer his question.
** Pay attention to which eye Sans uses when he winks in his dialogue portait: during a normal run, he uses his left eye, but during a No Mercy run, he uses his right eye. This is because his left one is the one he seems to channel his powers through, as seen when it glows during his attacks when you fight him, implying that when he's confirmed that you're a potential threat, he keeps his left eye trained on you at all times.
** [[https://imgur.com/a/e98F8 Compare]] Sans' 'asleep' sprite and his winking sprite. Notice the difference between the way the eyes look? He's not actually asleep, he's trying to trick you again.
** There's one area in Snowdin where Sans will teleport back and forth using his OffscreenTeleportation to the point of parody. He's deliberately dropping a hint towards his knowledge about the temporal paradoxes and his shortcuts. Also, while Sans normally turns his sprite to face the player character when spoken to, he's unceasingly staring right at the screen. Since the No Mercy path makes it clear that he's aware that Frisk and the player are separate entities, he's flaunting his powers while staring at ''you'' to let you know that he's aware of your existence.
** Papyrus' attacks consist of, of course, bones, but they're suspiciously shaped like text cursors with the flat top and bottom. Given that Papyrus is also a typeface, this is probably another reference to his ties to the fonts. This also applies to Sans, who is named after Comic Sans.
** If you call Papyrus outside of Alphys' lab, he, [[CloudCuckoolander being Papyrus]], winds up pronouncing it "Labrador-y" and wonders if that means there are dogs inside of it. Sans chimes in with a wink that he wouldn't rule it out. The True Lab has Endogeny, meaning Sans knows that, at the very least, the dog sentries' parents never left Alphys' lab, though he doesn't drop any hints that he knows [[BodyHorror their fate.]]
** During the Papyrus date, if you look in the sink drawer, you find the Annoying Dog stealing a bone, and after Papyrus fails to catch him, Sans comes out of his room and plays a Trombone. Yes, a Trom[[StealthPun BONE]].
** In a No Mercy run, if you've died four times in a row to Sans, he will tell you, "that's the expression of somebody who's died quice in a row. quice? frice?" [[StealthPun "Frice", as in "fries". As in what you would've had for lunch with Sans if you maintained a non-Genocide run up to sparing Papyrus.]]
** Sans is a Pundead.
* Papyrus' comment about needing 12 more followers to get a 2-digit number makes sense when you remember that hexidecimal notation is common in computers, suggesting he has 4 friends online.
* Sans killing you after you spare him seems trollish of him, [[PayEvilUntoEvil but it's pretty much sweet karma. You killed his brother when he was sparing you, so he was just showing you the utter betrayal he felt]].
* Sans' speech during the YouAreNotAlone segment before the True Pacifist final boss seems to pretty much be Sans being Sans, but look a bit deeper at his wording, "What, you still haven't beaten this guy yet?" Since he can observe timelines, he's probably aware that the one he's in is one that keeps going after Frisk leaves the Underground, so while the others are egging you on in their belief in you, Sans is doing it because he knows as an absolute certainty that you'll win.
* Examining the dog couple's hut in Snowdin, you'll find coloured definitions of the threat levels — White, Blue, and Green; however, the word Green is actually coloured Red. Dogs are red-green colourblind.
* When you talk to Papyrus during his date or hangout, he talks about how Sans tried making a "quiche" with a sugary substance instead of egg. In other words, pie. An early indicator that he knows Toriel.
* Sans being the first character you encounter in Snowdin may seem a bit odd at first, until you remember that Toriel asked him to protect any humans who came through his area. He even comes up to you from behind — meaning he was walking away from the Ruins! He didn't just passively accept Toriel's request; he was ''waiting'' for you from the start!
** He and Papyrus were also ordered by Undyne to capture any human that falls down. A fallen child would pass the ruins, thus him being right by the entrance would be the correct place to be. Depending on which run the player goes for, he will either regret his decision to listen to Toriel instead of Undyne or not.
* If you kill just about every leader and enough monsters to make Sans disgusted with you, but still get a Neutral Ending, he ends with two very chilling words: "see ya." At first, it seems like an open threat, until you remember that Sans is fully aware of the player's ability to start everything from the beginning. So, if you want to get one of the two true endings, you ''will'' see him again on the next playthrough — either as your friend, or as your [[ThatOneBoss worst nightmare]].
* Sans also does something similar in his phone call at the end of a pacifistic Neutral route where he says "be seeing you, ok, buddy". He knows that you're going to come back and fully expects you to give them their happy ending.
* Out of all the characters' {{leitmotif}}s, only Sans' is just named after him, except for Asgore's. It's well-established that Asgore [[GiverOfLameNames sucks at naming things]], so what's Sans' excuse? [[BrilliantButLazy Laziness.]]
* When you defeat Sans in the No Mercy run, why does he seem to bleed when skeletons have no circulation system? It's because he loves drinking ketchup at Grillby's!
** ...Except it's established by an NPC that monster food is unlike human food: it does not spoil, and does not pass through the whole body(thus the lack of bathrooms). Though the cause is unknown, it's meant to invoke the realization that you have just tried to murder someone who did nothing but try to befriend you and promised to protect you.
* Papyrus' plan of calling ''every cell phone'' to find Frisk's number seems ludicrous at first glance. On the overworld, where there are ''millions'' of cell phones, it would certainly be this way. In the underworld, however, there are far fewer active lines: if you consider that Mettaton, the underworld's greatest superstar, only has ''three dozen fans'', it seems likely that there are no more than 20 or 30 cell phones active overall. It would then be easy for him to request the underworld's client list using Undyne's authority "in an effort to find the human" and call every single number. Papyrus would need 30 minutes at most to find the right one.
* The fact that Papyrus ''never'' lets the player drop below 1 HP, even by accident. Remember who has 1 HP in total? It makes sense that Papyrus, more than any other monster, is used to being very careful not to hurt someone else.
* Why does Sans sleep a lot? The kid at Snowed Inn mentions that sleeping raises your HP above max. Since Sans's max HP is only one, one hit would normally kill him. By sleeping a lot, he decreases his chance of dying even accidentally.
* Both of the Skelebros tire themselves out during their fights, and both get pooped out completely after launching their ridiculously long ending attacks.
* The Dogi, if spared by petting them, become nuzzle-nose champions at the end, claiming the title from Asgore and Toriel. Your actions open them to the notion of dogs petting other dogs, so petting each other as they nuzzled may very well have factored into their victory the next time they competed.
** Alternatively: If Asgore and Toriel were still separated during the next nuzzle-nose competition, they might have opted out of competing. With their only real competition gone (keep in mind the Dogi were second place), claiming the #1 spot would be relatively easy for the Dogi.
* Sans's checkpoint just outside the ruins has bottles of ketchup, mustard, and relish inside it, but you cannot pick them up. Why is that? Because they're just [[StealthPun flavor text.]]
* Why does Sans hate making promises and try to avoid it? He is [[HyperAwareness extremely observant and perceptive]] (guessing correctly what happens in other timelines in spite of not actually remembering them based on simple clues, anticipating and dodging Fallen Child's attacks ''even while asleep''), and is implied to be rather close to [[TragicVillain Asgore]] (not as close as [[TheDragon Undyne]] or [[ReluctantMadScientist Alphys]], but still closer than most monsters). Asgore's whole life was ruined by one promise that he made in a fit of rage and despair and now has to fulfill, even though he ''really'' doesn't want to. He makes an effort to [[StepfordSmiler hide it behind a nice, happy attitude]] and is good enough at it to convince most monsters, including the aformentioned Alphys and Undyne, that he really wants to free them at any cost — but Sans wouldn't be fooled. He avoids making any promises, because he doesn't want to make the same mistake.
* Why does Sans look overweight despite being a skeleton? He's [[StealthPun BIG BONED.]]
* One combined with sadness. Snowdrake's father comments that Snowy ran away after his mother died, and both Snowy and his father imply that their relationship is very, very strained. Then you go to the True Lab, and find out that Snowy's mother is there — she had "fallen down" and was comatose, and was sent to Alphys for experimentation. Alphys meant to send the dust back to the families of the monsters for funerals, but they didn't crumble after they were injected with Determination. ''Then'', they woke up, and Alphys wrote to the families, Snowy and his dad included, that everyone was alive. And then... she never responds to anyone's calls or letters, says anything about what's going on, or sends the supposedly-alive subjects home. Unintentionally or not, Alphys really [[YankTheDogsChain yanked the dog's chain here, giving the families a flicker of hope before snatching it away, without so much as an explanation]]. Snowy's not just acting out because he lost his mom; he's acting out because he's emotional and angry, and because he never got any real closure, which could've helped him process, grieve properly, and cope in a healthy way. It makes even more sense when you consider that Snowy's a teenager. [[YouthIsWastedOnTheDumb Teens aren't known for being the most rational of creatures at the best of times]], but a teenager that's gone through what Snowy has? Of ''course'' he'd lash out at his father and do something impulsive, like run away from home.
* You can buy the Tough Glove from the shopkeep in Snowdin, even though you get it for free inside the first dimensional box you find. If each weapon belonged to a previous human, why is this the only one you can acquire two of? Because it's actually a pair of gloves, left and right.
* Of ''course'' almost nobody donated to the Dog Shrine in the [[UsefulNotes/NintendoSwitch Switch]] version. Without the [[AchievementSystem trophies]] of the [[UsefulNotes/PlayStation4 PS4]] version, there's no real incentive to.

[[AC:Waterfall / Undyne and Napstablook]]
* When buying the Glasses and Torn Notebook from the Waterfall shop, the stats state that your invincibility frames increase. Which makes sense: the glasses are clouded, the notebook is torn. You must look so pathetic and weak that the monsters go easier on you.
* Undyne has more DEF without her armor than with. This could be because the armor is meant to shield her SOUL from attacks, as monsters seem to usually attack the SOUL, not the body. Thus, it is useless against attacks to the "body", and may even actively hinder her blocking. Conversely, without armor to weigh her down, she's able to move and block more effectively, thus her increased DEF when unarmored.
** Alternatively, it's because the only time you fight her without her armor, you've already gone to immense lengths to spare and befriend her (which, by the way, is only possible if you've been a pacifist to everyone else, too). She's not stronger; ''you're weaker'', because the protagonist can't muster the ill will to do her any real harm.
*** It's not even that you're weaker. The fact that the protagonist is unwilling to hurt her is the ''entire reason'' why your attacks barely do anything in that "fight".
* The music that plays during Undyne's death on the Neutral run is a mix of her regular theme and "Battle Against A True Hero." She's ''trying'' to muster the determination to take on her Undying form like on Genocide, but because of that lingering doubt that you might still be a good person on the inside, she can't do it. You might have brought Undyne's HP to zero, but it was her own internal conflict that killed her.
** This could also explain why, during a Genocide Run, she '''is''' able to take on her Undying form. She saw you about to murder an innocent child, and when she [[HeroicSacrifice pushed him out of the way]], she felt all the damage your attack did — and it's usually in the 10,000s. In other words, Undyne felt the immense hatred and killing intent you had towards the Monster Kid and was utterly convinced that there was no good in you at all.
* During your hangout with Undyne, she states: "some mean human will fall down here, and I'll take their soul instead." Fast-forward to Undyne the Undying.
* During the Mad Dummy's boss fight, we get to hear [[CallBack Napstablook's]] theme all the while. The Mad Dummy is prone to repeating some of its words thrice. [[https://www.youtube.com/watch?v=N3epEVMNJdY Go ahead, pay attention to how the music goes.]]
* Napstablook:
** Napstablook's name makes little sense when you first meet them, but when you get to their house, you discover they're a music aficionado. They're a Napster bloke.
** You also first encounter them when they're pretending to sleep and blocking your way, preventing you from progressing. Naps-ta-block.
* The prophecy described on the walls of Waterfall and mentioned by several characters is ambiguously interpreted. Some believe the Angel will free them all from being trapped in the Underground, while others see it as a macabre Angel of Death who will free them from their eternal malaise by ending their lives. This seems to most reflect the Pacifist ending, which contains both — Asriel as an actual angel of death who's emptied the Underground by consuming all the monster souls at once and then later uses their combined power along with the human souls to break the barrier, allowing the monsters to be free. The No Mercy ending, where the player eradicates all of the monsters in the Underground themself, also falls under the latter description.
* In a No Mercy run, there's no save point before Undyne the Undying until after dying to her once (which [[ThatOneBoss you probably will]]). This is because she's the first ''real'' challenge you've been made to face — everything to that point has been [[CurbStompBattle a curb stomp]] — thus the determination and excitement of an actual test creates a SAVE point where one wouldn't be on any other run.
* Undyne's death animations in any run always involve her beginning to melt. It's apparent that Undyne truly is badass enough to delay her own death, making her the only monster in the whole underground capable of generating her own Determination. Unfortunately, she's still a monster, so while it lets her revive multiple times for a short while, it ultimately causes her body to melt just like the Amalgamates after she uses it for too long.
* Another moment with Undyne makes a lot more sense in hindsight — you're wandering through the darkness and you find an echo flower… which ominously says "behind you." Naturally, Undyne is lurking and ready to fight you. The brilliance kicks in once you realize that someone had to say "behind you" to the flower — it was Undyne, going off the VoiceGrunting, who believes that anime is real and set up a suitably dramatic encounter.
* In a more literal case of Fridge Brilliance than most: Undyne's "hot fridge" might seem like a bad idea… unless you've spoken to the toothy monster at Grillby's and remember that monster food doesn't spoil. For monsters, whether a fridge is cold or hot really is just a matter of preference.
* Sans' prank where he uses the telescope to leave a mark around Frisk's eye at first seems like a goofy Sans prank. However, it has a practical use too: Sans is trying to see if you, the player, are in control. Logically, Frisk probably wouldn't be able to see the ring around their eye, but you would, once you turned Frisk to the screen. Sans just wants to make sure what to expect from this particular timeline.
* If you sing with Shyren and have spared Papyrus, Sans will appear and start selling tickets made of toilet paper. This seems odd, since monsters explicitly [[NobodyPoops don't excrete]], but keep in mind that a lot of trash from the surface ends up underground.
* During Undyne's friendship "date" she tells the tale of how she became the head of the Royal Guard. As a kid Undyne tried to fight Asgore, who both dodged every attack of hers and utterly refused to fight back. Which is exactly what the player must do, not just with Undyne, but everyone up to that point in order to befriend Undyne and hear that story to begin with. You have to emulate her idol to gain Undyne's friendship and stick with what she admires about Asgore throughout the game order to keep it.
* In Undyne’s Genocide Route Song Battle Against a True Hero, you can hear a sped-up version of Don’t Give Up. Of course, she is [[ArcWords determined]] to strike you down.
* Also, both Papyrus’ and Undyne’s catchphrases sound very similar (“NYEH HEH HEH!” and “NGAHHHH!!”)
* If you Check Napstablook's stats while fighting them, they actually react to the narrator's statement that they don't seem to have a sense of humor. If you subscribe to the theory that Chara is the narrator, this would be further evidence in that regard - if any monster could sense the spirit of a dead human, it would probably be a ghost.

[[AC:Hotland / Alphys and Mettaton]]
* Why the heck is Mettaton EX so obsessed with his legs? Well, as a ghost, he never had legs or arms, and as his box form, he still had no legs.
* Why does Mettaton NEO go down so easily in a Genocide Run? When you think about it, it's very likely that he was a rushed production on Alphys' part. To elaborate, Mettaton has an infatuation for the human world, so there's no way he would ask Alphys to intentionally turn him into a human-killing machine from the get-go unless ''absolutely'' necessary, and when Frisk started to gain an advantage over Undyne the Undying, that was probably the point when she deemed things went to shit, forcing her to make some last-minute adjustments to Mettaton whilst also evacuating the monster population.
** Also, Mettaton isn't a true robot. He is a ghost possessing a robotic body which he had made his own for good. He is a monster and has the same weakness to KillingIntent as the rest.
** The fact that he can comment on his lack of defense could reinforce the idea of Alphys rushing him. It's been pointed out that Mettaton [=NEO=] is deliberately wasting time to let Alphys escape, as evidenced by his opening text being "Mettaon NEO blocks the way!" instead of mentioning him attacking or doing otherwise; that might not be what she intended for him to do, though. Alphys probably poured what little time she had into improving Mettaton's attack in the hopes that he'd actually be able to kill Frisk.
*** [=CHECKing=] his stats proves this as well. Box Mettaton has an ATK of 30 and a DEF of 255. Mettaton NEO, though, has 90 ATK (even more than Toriel and Asgore), but only 9 DEF. The idea was that he might get killed in one hit, but as everyone is unaware of the "Player attacks first" rule, they probably hoped that he could get in one good hit to kill or at least slow down the player.
*** This is slightly undermined by the fact that if you give him a chance to act by [=CHECKing=], missing, trying to spare him, or otherwise screwing around, Mettaton NEO does absolutely nothing. Either he has no idea how to actually ''use'' his new form's combat functions, or he's too damn scared of you to move.
*** Well, yes; it explicitly says that he's "blocking the way." The idea is that while Mettaton NEO simply ''refuses'' to fight you, his ridiculous attack score running contrary to him not doing anything means that ''Alphys'' hoped he'd fight you. Or to put it more simply, Mettaton's just not doing what he was "meant to," though his dialogue implies more out of HonorBeforeReason rather than fear.
*** We learn in the Pacifist/Neutral Run that his human form has some serious energy problems (after all, if he isn't killed, he will still shut down). Mettaton NEO is at least thrice as elaborate, so chances are, whatever attacks he has, they would either make him break down mid-attack or he doesn't even have the energy resources to start them; his energy reserves are probably barely enough to stand in your way without shutting down.
** Mettaton NEO's theme, Power of NEO, is a remix of Battle Against a True Hero. This might be just to trick you into thinking Mettaton NEO is a difficult boss, but it is justified in-game because both want to kill you to ensure everyone else's survival... but also because Alphys built Mettaton NEO, and since she saw your fight against Undyne, it inspired her to create Mettaton NEO as a tribute to the one she loved.
** Killing Mettaton NEO nets you a metric ton of EXP, enough to raise your LOVE to 19. Until now, you've been slaughtering dogs, bugs, slime, seahorses, airplanes, and sentient fire, with the most humanized monsters being a goat woman, a skeleton, and a fish woman. Aside from his ArmCannon, Mettaton NEO looks extremely closely like a human, and your willingness to cut him down shows how willing you are to kill an actual human.
** Even if you hit Mettaton NEO at full strength on a run where you haven't killed all of Hotland's population, why does he say that you were holding back? Because you haven't gained the maximum amount of EXP and LOVE that you could've.
* The quiz question about smooching a ghost with only one possible answer seems odd, until you realize Mettaton is a former ghost himself, so this might be a flirty behaviour or just an effort to get a little care.
* Mettaton EX has the most human appearance of all the monsters. Makes sense, given that he wants to be a star on the surface.
* Why is Mettaton almost invulnerable as a box? Well, if your damage is based on killing intent, how badly could you really want to kill a robot? It's not like it's a living being, only a box with some lights on a wheel. There's ''nothing'' to kill as far as the Player Character is concerned. Tsunderplane has a wig and Mettaton NEO and EX look almost human, so it would make sense why you could "humanize" them and harness the killing intent.
* Mettaton's final battle theme in a neutral/pacifist run is called "Death By Glamour". While it can refer to how he wants to put on a show while he tries to kill the player, it can also refer to how his desire to have a more physically appealing body could lead to his downfall.
* Why does Alphys wind up with Undyne, at long last? Well, there are such things as [[https://en.wikipedia.org/wiki/New_Mexico_whiptail lesbian lizards.]]
* Why would Alphys think to have a bathroom of all things — something it's established that monsters have zero need for — in her lab as a cover for the True Lab entrance? Well, she ''is'' a fan of human culture — her installing one in her home as a place where someone'd go for privacy might come off to anyone who knows her as plausibly related to her hobbies enough not to be worth questioning.
* During the Mettaton EX fight, the ratings meter will start to rapidly drop while in the player menu. After all, you're just standing there choosing what to do, which probably isn't very interesting to watch, and the monsters are going to start tuning out from boredom.
* Alphys gets a lot of shit for inserting herself into Frisk's story in order to see herself as the hero who can fix everything, going so far as to literally watch all their progress on a screen and become attached. Guess who else does that? You. On a Pacifist run, to literally everyone in the game.[[note]]Maybe with some stress on the inside...[[/note]]
* It makes sense that Alphys, based on a lizard, has a lab/home in Hotland, the warmest part of the underground. Lizards are, like all reptiles, cold-blooded and need to spend time in the warmth to not freeze to death. This is especially important because besides the hole Frisk initially falls down in Home, it doesn't look like any other parts of the mountain had fallen away to reveal sunlight.
* The only Neutral endings in which Alphys appears are the very worst Neutral ending where you fail a Genocide Run (abort a Genocide Run in Hotland) and the very best Neutral ending where you fail a True Pacifist Run (kill no one, deliver Undyne’s letter, but don’t go to the True Lab).
* Alphy's master plan, as explained by Mettaton is to make the human like her so much, they won't want to leave. If she had suceeded, it would actually accomplish the goal that Asgore had assigned her. Keep the human from reaching the Palace.
* In the Neutral ending where Asgore, Toriel, and Undyne (but not necessarily Papyrus) are dead, Mettaton becomes the new ruler. After all, to spare him, you have to boost his ratings to an ungodly degree.

[[AC:New Home / Asgore]]
* The kitchen in Asgore's home has a wastebasket full of pie recipes. Why? Because he's spent countless tries with different recipes to replicate the pies Toriel used to make.
** In a similar way, almost all the plants in the Ruins are dead, specifically the tree, while Asgore has his house overflowing with flowers. Toriel is bad with plants, and without Asgore taking care of them, they all die.
* Why did Asgore destroy the "Mercy" button? …Because after all he's done, he feels that he doesn't deserve mercy.
** Another interpretation is that Asgore is such a softy (seriously) you'd be able to Spare him right off the bat if you showed him mercy.
** Another interpretation is that he knows you will keep loading, and is only attacking you [[SuicideByCop to make absolutely sure that you kill him]].
** This is the same reason he doesn't meet your gaze in battle. He doesn't want to see you as human, as a living being with feelings and compassion like him, because it would make it all the more difficult for him to bring himself to kill you. In destroying the option for mercy, he's desperately trying to force you into attacking him, in the hopes that it'll give him some measure of a reason to hate you, so that he can (attempt to) bear the burden of killing you, a child.
** In the Asgore fight, eating Toriel's pie lowers Asgore's ATK and DEF stats. On an obvious level, this is due to being reminded of her... but it could also be partly because, if ''you'' have the pie, it means that Toriel cared about you, possibly as much as a family member. Asgore may have realized that, in attempting to avenge the children he'd shared with Toriel, he may essentially have to kill one of her own children.
** You can only Talk to Asgore to damage his will to FIGHT and lower his offense and defense if you haven't killed anything. This is presumably because on a neutral run, someone, probably Sans, is sending word that the player is willing to kill in self-defense, so he can bring himself to dehumanize you, whereas if you're on a Pacifist run, your telling him to stop makes him face the reality of the situation — he's trying to kill a harmless child who doesn't deserve to die, and while he still feels that he can't surrender, he can't muster the same justification to attack you with intent to kill.
** Trying to talk to Asgore on a non-pacifist, non-Genocide run results in the game commenting "But there was nothing to say". You can't bring yourself to try and convince Asgore to spare you, because [[NotSoDifferent you too were responsible for another's death in order to escape the underground]].
* Asgore is ''extremely'' reluctant to fight you — he drags the confrontation out for as long as he possibly can, and gives you ''many'' opportunities to back out. Frisk is the first human to meet him ''face to face'' — all of the others' belongings were found, presumably, where they died — a ''long'' way from New Home and Asgore himself.
** Actually, Toby Fox has confirmed that Asgore killed them all, which is Fridge Horror in itself.
* Because Asgore is deliberately not looking at you during his boss battle, all of his attacks are aimed in your general direction, not specifically ''at'' you. Even his trident attacks are in wide swings instead of a potentially more effective jab.

[[AC:General]]
* You may note that ''every area'', not just Home and New Home, was probably named by Asgore because... well, they all have a really uninspired, borderline LineOfSightName. Snowdin and Waterfall only really get a pass because it's not uncommon for areas to follow that particular naming scheme in other {{Role Playing Game}}s.
* At first glance, the order in which you traverse the areas of the Underground seem purely like SeasonalBaggage more than anything else, given you go through Autumn (the Ruins), Winter (Snowdin), Spring (Waterfall), and Summer (Hotland) in perfect order. However, it makes sense ''geographically'' as well. Waterfall is filled with water, and is smack-dab in the middle of [[SlippySlideyIceWorld Snowdin]] and [[LethalLavaLand Hotland]]. The heat radiating from Hotland most likely allowed for any ice or snow in Waterfall to melt.
** The Ruins are themed after Autumn, which is also called Fall. How do all humans end up in the Ruins again? They ''fall'' in.
* The monsters seem to use "going to the bathroom" as their version of INeedToGoIronMyDog, which makes sense since monster food is specifically stated to be made out of magic, which allows it to be digested without producing any waste products, making toilets unnecessary. Papyrus uses the phrase as an excuse to allow you to date Undyne, and Alphys has what appears to be a bathroom inside her laboratory which she states she's going to use when she gets too embarassed to stay in the same room with the main character due to not being able to think of anything to say to them, but the room in question is actually a hidden elevator to the True Laboratory.
* Even with an infinite lifespan, Boss Monsters cannot mature if they have no parents to get life force from, resulting in sterility due to permanent childhood, and are universally docile, yet they rule Monsters. How have Monsters survived long enough to be banished in the first place? What about earlier before civilization, where they would literally be eaten alive? Because Monsters don't leave bodies, and therefore nothing to use as material or food. Killing them would literally be a waste of energy. With no natural predator, no wonder the most docile would be the ones ruling, because nothing can take advantage of them for it.
** [[HumansAreTheRealMonsters Except Humans]], who don't need something to gain.
* Meta Fridge with the Toriel Plush — the official plush contains a small plush "Soul" inside of it, but the only way you'd see it is to cut open the plush. From a business standpoint, adding such a thing would seem like a waste of time and resources for something most consumers wouldn't get to see, since few would be willing to damage something so cute that they paid for. Why is it there, then? It ties in perfectly with the theme of the game — how far are you willing to go to see every last secret for yourself?
** This brings YourSoulIsMine to a whole new physical level.
* The nice cream guy is a rabbit with blue fur, or in other words a [[https://en.wikipedia.org/wiki/Blue_Bunny "Blue Bunny,"]] selling ice cream!
* Sans’s judgments, as well as the Neutral Endings, are good or bad precisely in the order of how good or bad the player acted, which is more complicated than just “higher kill count means worse judgment and ending”:
** First, the best possible judgment you can get is only if you have killed nobody. This is not necessarily a True Pacifist Run though, because a player might still mess up and kill Asgore or Flowey, and even if they don’t they’ll still get a Neutral ending if they don’t go to the True Lab. However, killing Asgore or Flowey would be rather out of character for the player at that point, since they have learned how to solve their problems nonviolently.
** Approaching Sans with more than 0 Exp., but still LV 1, will make him disgusted with you. After all, it’s pretty much impossible that any player would do this without intending to, considering that there is no reason for a Neutral player to stop killing before having leveled up unless they already know the twist in advance, so Sans knows you’re just doing it to see what he’ll say.
** The same applies to a LV 2 player, with Sans saying “who gets to lv2 on accident?” Killing any monster outside the Ruins will put you above LV 2, and within the Ruins, you will reach that level in at most five battles (and that only in the unlikely case that they are all Whimsuns) which is less than the number of encounters you’ll have just making it to Toriel’s house. The Exp. curve just in the Ruins means that you’d likely get just enough Exp. to reach LV 3 unless you deliberately stopped fighting while still in the Ruins, which no first-timer would ever do. It may not be strictly ''impossible'' to reach LV 2 and no higher by accident, but it’s so unlikely that there is no need to consider it.
** Being at LV 3 gives the player the only judgment other than 0 Exp. that isn’t a TheReasonYouSuckSpeech in disguise. This is because someone playing the game blind will almost certainly be at this level when they reach Toriel and first start being shamed for killing monsters, so once they Reset and find a way to spare Toriel they will likely be a pacifist from then on, avoiding any unnecessary kills for the remainder of the game. Since the player still killed someone Sans still doesn’t give them a ''good'' grade, but recognizes that they weren’t doing it on purpose and so can be forgiven.
** Between LV 4 and 9 he says that the player deliberately killed at least some monsters, but admits that it may have been in self-defense so he isn’t sure how to judge them. It’s actually somewhat hard to reach New Home with a LOVE of exactly 4, due to how much Exp. monsters in later areas give out, so the most likely way would be if a player level grinded in the Ruins and, not knowing about the Genocide Route, was horrified upon first hearing the “And nobody came” message and resolved to spare everyone else. As for LV 5 through 9, a player will be towards the higher end of that range if they just play through like a normal RPG and kill all their RandomEncounters but don’t go out of their way to grind. Undyne alone will put them at LV 7 or 8, and since sparing her is a GuideDangIt, and she is the first monster to actually try to kill the player, it could be considered self-defense. And of course, killing a random monster outside the Ruins (doing this in the CORE gives enough Exp. to go from LV 1 to 5) is only likely to happen if one is doing it on purpose, since one would have to know how to spare by then.
** Between LV 10 and 14, Sans says that you’re failing and that you’ve probably already heard his judgment before and just want to hear them all, and at this point he’s right. Killing all the bosses won’t give you enough Exp. to reach LV 10 on their own, and even the encounters in the Ruins and Snowdin are a drop in the bucket compared to how much Exp. is required to level up at this point, so you must have been killing most of the RandomEncounters and even start to seek some out just to kill them. Though a player must have spared at least enough monsters to avoid fighting Undyne the Undying (and thus, Mettaton NEO) their excessively high body count means that they don’t value other lives and only demonstrated restraint to avoid fighting the Genocide-only bosses.
** Most players don’t know this, but it is actually possible to reach LV 15 or higher on a Neutral Route. Doing so by aborting a Genocide Run in Hotland will still have you fight Mettaton NEO and set your LOVE to 19 regardless of kill count, but just killing 40 monsters in Hotland is enough to do it even if one was a pacifist up to this point. As such, since you were either trying to go for the Genocide Route and failed, or killed a bunch of people in Hotland for no real gain, Sans says you suck at even being evil, and are certainly a horrible person regardless.
** And of course, if you actually killed ''everybody'' then Sans realizes that you cannot be reasoned with and must be stopped before you destroy everything, and since judging you would be pointless, decides to make you ''[[ThatOneBoss suffer]]''.
* As for the endings, it’s a similar idea, based on what Toby Fox thought a player who got such an ending deserved:
** If you kill no one but don’t meet the requirements for a True Pacifist ending, then you get the only Neutral ending that can be considered happy: everyone’s alive except [[DeathSeeker Asgore]] and the monsters are working on a way out without needing anyone’s soul. Of course, since Toby Fox wanted every player to fight Photoshop Flowey, he made some of the True Pacifist requirements only possible after getting at least one Neutral Ending, so this ending is only a placeholder until the player inevitably goes through the True Lab and gets the real ending. Note that Alphys can be here if the player went on her date but didn’t go to the Lab, showing that merely finishing the FetchQuest is not enough.
** If Toriel’s alive but at least one monster was killed, then things aren’t too bad, but the game really drives home how the monsters are pretty much stuck at the status quo ante. Since the most likely way the player got this ending was by being a pacifist up to befriending Undyne and then killing someone just to see what would happen, Undyne’s part of the conversation exists solely to guilt-trip them for doing such a horrible thing. This ending could also happen if a player killed monsters in the Ruins before realizing [[DeconstructionGame what kind of game this is]], and then went out of their way to avoid killing after that, so in that case there is instead an ending where Undyne is upset with you, but no one else is, since you didn’t know you were doing anything wrong and stopped when you figured it out.
** If you killed more than ten monsters, or any bosses, on the other hand, then it’s clear that you did kill at least one monster on purpose despite knowing its unnecessary. If you left all the bosses alive, then the game is shaming you for [[WhatMeasureIsAMook showing favoritism to the characters you can personally befriend and not caring about anyone else]]. Papyrus will always spare you before you can deplete his HP, so killing him cannot possibly be rationalized as self-defense. It’s still possible that someone playing blind would do it for the Exp., but at that point they’re already showing the weakness of character that would push them to do a Genocide Run later, hence they’d deserve it when Sans says they’re not welcome. As for killing Undyne, the very fact that you made it past Toriel nonlethally means you should be assuming that the same applies to all monsters, so killing Undyne means you’re too lazy to figure out a way to spare her, and don’t really deserve a happy ending. But you still aren’t nearly as bad as you could be, so Frisk and mankind are safe at least.
** If Toriel is dead, then not only did the player not even try to spare her, but it didn’t occur to them to reload their save to bring her back, if she was killed by accident. The game assumes the latter if the player does ''not'' kill Undyne since doing so is also very unintuitive, implying the player is doing it on purpose and as such, doesn’t deserve a better ending than one where the player character, and possibly humanity in general, is in danger.
** On the other hand, it is possible for a first-time player to end up killing both Toriel and Undyne just because they mistakenly think they have no choice. In that case the game doesn’t really hold it against them, though the endings where Mettaton and Papyrus are in charge are both pretty melancholy. Hey, you ''did'' kill someone.
** If a player just plays through like a normal RPG the whole way, then that entails killing all the bosses. The suckiness of this ending isn’t solely to punish the player, but just to point out the logical consequences of their actions, and hopefully get them to listen to Flowey’s recommendation not to kill anyone next time.
** Aborting a Genocide Run in Hotland is only likely to happen if the player is aware of the consequences of completing the run, so Alphys [[TheReasonYouSuckSpeech tells you exactly what kind of a horrible person you are]].
** The ending where the Annoying Dog becomes king, everyone is happy, and ''Sans doesn’t even care that you killed his brother'' is the anomaly here, since the requirements are such that nobody would ever get it by accident, due to Papyrus always offering the player mercy. But the ending is a joke anyway. It was likely done just because the ''other'' bosses could plausibly be killed by a first-timer who thinks they have no choice, and to get this ending one would need to deliberately avoid killing any normal civilians, who are all innocent in this, showing that the player can distinguish right from wrong.


[[AC:Genocide- or Pacifist-Specific]]
* Why does Flowey take multiple hits to kill, despite Chara being at the height of their killing intent? People may assume it's because he's an actual flower instead of being made of magic, but look at him just before the act. His face takes on the appearance of Asriel, the only person Chara may still have affection for at this point. It's possible their killing intent is weaker for him than any other monster.
** Either that... or they didn't want to ''kill'' him as much as they wanted to make him suffer. Flowey does mention that, early on...
** Note that despite Chara seemingly killing Asgore without any input from you, there's hesitation from them here. You have to push the button. You have to push them to kill Asriel, their brother, their best friend. You have to push them over the edge.
* In his boss battle, Sans tells you, "To be blunt...it makes it kind of hard to give it my all," as he describes why he took so long to engage you. It's well-known that this battle is ''[[ThatOneBoss DIFFICULT]],'' and the player most likely has had to fight him over and over. After a couple of rounds, the player gets impatient and starts skipping through Sans' dialogue...''and'' the fight bar. Since Sans can't be hit anyways, you're no longer giving the attacks your all either — you're just stopping the fight meter as quickly as possible, even if it misses or would do minimal damage. Looks like Sans really is getting to you, the player, in a very NotSoDifferent kind of scenario. Sans is going through exactly what you are in regards to his attacks never working, but the difference is that he's putting his heart into his attacks anyways.
** In the soundtrack, Sans' battle theme is "That Song That Might Play If You Fight Sans", but in the game itself, his theme is actually "Megalovania." It makes perfect sense for the most meta character in the game with the most misleading stats, appearance, and personality to mislead you with his battle theme too. Imagine the shock on players' faces when they expect a song similar to "Bonestrousle" but get a serious, frantic beatdown song.
* In the True Pacifist ending, right as Flowey collects every monster's SOUL together, you'll notice that Undyne is the only one struggling; even Sans is dormant. Seeing how powerful Sans is, this might seem odd until you remember that Sans only has one hit point. A single hit from Flowey may have temporarily knocked him out.
** Given that, in Flowey's own words, Sans is the major obstacle that has always kept him from reaching Asgore, he probably made sure to apply just enough pressure to keep the skeleton from interacting to be absolutely certain Sans wouldn't jump in.
*** Continuing this, a reason Undyne isn't also receiving the correct amount of pressure (considering that she can still struggle) may be that Flowey sneaks around. Sans, due to his knowledge and teleportation ability, would always be in the way. Undyne, however, is more easily avoided. So Flowey could just not know how powerful and determined Undyne can get because they never fought.
*** Monsters' attack and defense power are based on magic, and Flowey is using physical restraints. The Mad Dummy confirms that magic and physical attacks are different in this world, so it makes sense that the other monsters – physically weaker than Undyne – can't hold their own. If, say, Asgore or Toriel wanted to burn their way out, that would work regardless of how tight the vine was, but since Undyne can bench press literal benches of kids and suplex boulders, she does better in this specific situation.
* We all know that the boss fight against Sans is insanely difficult. But a question comes up: why would he give you a chance to proceed at all? We know from his false mercy offer that he can execute unavoidable {{One Hit Kill}}s, so why does he not do this earlier, or every chance he gets? This is because, depending on the route taken, ''Undertale'' is a deconstruction/reconstruction of RPG video games. As we can see from earlier dialogue in the No Mercy ending, no matter what Flowey did with his power to SAVE, the characterization of all the inhabitants of the Underground remained the same. The Fallen Child/the Player is the only thing that isn't completely predictable. And despite his badassery, Sans is the same — he can't escape his role. Ultimately, Sans is a video game boss. It is in his nature to be beatable, and he can't escape from it.
** Alternately, he doesn't intercede for the same reason for his general laziness and apathy — he assumes that everything would be reset anyway, so why even bother? It's only when he realizes that you're about to do something that [[PointOfNoReturn can't be reset]] — and given that pretty much every boss fight save Mettaton on the Genocide route is effectively crossing a MoralEventHorizon on its own, that's saying a lot — that he realizes he has to step in.
** It seemed a bit obvious to me that the only reason he could use a One-Hit Kill is if you lowered your guard. When you choose to give him MERCY, you're setting the knife down. It's like once you have the option to SPARE an enemy, you can one-shot them — Sans is getting you to the point where he can SPARE you by using the same trick you would use.
** Alternatively, judging by Sans's pose when he says "come here, pal.", it's because he's brought you into a hug, making it impossible to dodge regardless. The bullet box filling up with bones is just an interface representation of the fact that you're [[ImpaledWithExtremePrejudice taking an attack point-blank and you can't escape from it]], rather than any trait of the attack itself. He did say that showing mercy would make his task easier, after all.
*** Similarly, allowing you to get close enough to hug him means allowing you to get close enough to attack before he can dodge. He needs to be certain he can attack before he risks doing that.
** If you somehow[[note]]possibly by hacking[[/note]] manage to survive his unavoidable attack, the bones will disappear, but the turn won't end, leaving you in an {{unwinnable}} scenario. Sans is punishing you for cheating by — much like with his "special attack" -- never giving you your turn again, leaving {{ragequit}}ting (or debug mode) as the only option(s) available. And since you went one step further and cheated death, he doesn't even give you the option to push the dodge box to the FIGHT button.
* Sans sticking to his promise to Toriel despite his brother's death makes even more sense when you consider his overall apathy, since he knows that the world may be reset at any time. He's angry, sure, but "this, too, shall pass" — right up until it looks like you may actually win for good.
* Combined with FridgeHorror — Why is Mettaton NEO so easy to kill? Because he was meant to be a HUMAN eradication robot. By the time you reach him, you're not really human. Speaking of which, that's why Sans gets the first turn in his boss fight, that's why he is able to dodge attacks when nobody else could, that's why he is able to grant fake mercy, and that's why he is able to pause the fight just so you can't kill him. Think about it — you always get the first turn, you're able to dodge attacks (heck, it's even possible to beat Sans without getting hit ONCE), you're able to make monsters sparable and ''then'' kill them, and you're able to pause the fight so the enemy cannot attack you for a short span of time until you do something. Yup. At that point, Sans is more of a human player character than '''you''' are. You aren't fighting Sans. Sans is fighting you.
** That's why the [[ExactlyWhatItSaysOnTheTin Song That Might Play When You Fight Sans]] doesn't play in the battle. It's Sans' battle theme, a supercharged remix of his Leitmotif, including elements of Papyrus' battle theme and Gaster's theme. Instead, the [[SugarWiki/AwesomeMusic admittedly awesome track]] [[AutobotsRockOut Megalovania]] plays. Sans is fighting you. Megalovania isn't ''his'' theme, it's '''''YOURS'''''. '''''YOU''''' are the FinalBoss and he's trying to stop you from triggering TheEndOfTheWorldAsWeKnowIt.
* In the True Pacifist ending, we see monsters reintegrating with human society, complete with getting driver's licences. Toriel even gets to open her own school. But how can they manage to do all of this? Well, the fact that they're a society who still used gold as common currency stepping into a world where even a little gold is quite valuable ''miiiiight'' have helped with some of that... if not just the purchasing things, then also bribing the humans to let them live.
** And when you consider the fact that human wizards are a thing in the Undertale universe, it's quite possible that the magic didn't just go away as time passed, so the humans are used to weird things happening. It's also possible that there a still some monsters around, if you consider the possibility that the urban legendary monsters like the sasquatch and nessie could be around in their universe.
* Sans is both a skeleton and a monster, so why would he bleed when the Fallen Child attacks him? Well, if you refuse Sans when he offers you ketchup in Grillby's, he drinks it all. Sans didn't bleed, he was leaking ketchup. [[EpilepticTrees Or he is secretly human.]]
** The only problem with this is, getting to the point of fighting Sans involves killing Papyrus, which causes Sans to vanish until you get to the judgement hall, and Sans doesn't take you to Grillby's until you get to Waterfall after the fight with Papyrus.
*** He still could have gone on his own sometime before his boss fight, especially considering he outright mentions Grillby's after you beat him. That, or given his fondness for ketchup, he could just keep some on him, which could be considered a FridgeBrilliance on its own.
* Why does the True Pacifist run require, well, being a True Pacifist? Because it involves succeeding in destroying the barrier, which requires the power of 7 human [=SOULs=]. Since they only have 6, the only conventional way to get the 7th would be if Frisk died, which just isn't going to happen. It's mentioned that human [=SOULs=] are so powerful that it would take the [=SOULs=] of every monster in the underground to match one. That's literal — Flowey's backup plan when 6 [=SOULs=] aren't enough to defeat you is to gain an artificial 7th by absorbing every single monster and getting the power of a God without yours. If you kill even a single monster, he can't complete that plan because he wouldn't have enough power to create a false 7th SOUL.
** The True Pacifist route runs even deeper than that, really. If the player doesn't complete the True Lab portion of the game, the player is shunted into a Neutral Path. The Amalgamates must be freed for Flowey/Asriel to make the 7th soul. Without them, he simply doesn't have enough monster [=SOULs=] to create the 7th SOUL from scratch. The True Pacifist route requires befriending ''all'' monsters and freeing ''all'' monster [=SOULs=] in the Underground, not just those who are easily accessed during normal gameplay. And even then, given the amount of monster [=SOULs=] to make a human SOUL, the specific amount of souls required begs the question "what would happen if the Amalgamates weren't there?" Flowey wouldn't be able to create the artificial soul, presumably. (The game hints at this, what with the shoving onto a Neutral path if the True Lab isn't fully unlocked. Alphys will talk to the player once the game is over if the player goes on the date with her, further implying that befriending Alphys isn't enough; the events in the True Lab must be accomplished to gain the GoldenEnding.) So who gave Alphys the original idea to preserve the souls of the fallen monsters via DETERMINATION injection? What even caused them to 'fall' in the first place? Did another character already have a plan in place and Alphys was merely following what this monster had already laid out? And if so, who was the monster behind it all? Was it [[DeconstructedTrope Dr. W.D.]] [[DummiedOut Gaster?]]
** On a similar note, you're only told to go to the True Lab on a True Pacifist run; not on a Neutral — one death, even accidental, bars you from it. If the Amalgamates really are necessary to create that false 7th soul, then Flowey only feels safe having you go there if you go out of your way to avoid killing anyone no matter what. Anyone less than a FriendToAllLivingThings would likely take one look at [[EldritchAbomination those monstrosities]] and think [[OhCrap something along the lines of]] "KillItWithFire", which would ruin Flowey's plan. He needs to make absolutely sure there's no risk of you killing them before he can tell Papyrus to send you there.
* To beat you during a No Mercy run, Sans has to go out of his way to use an InterfaceScrew — when his regular attacks fail, that is. You turn the tables and do the exact same thing to him, attacking twice in one turn after physically moving the box confining your heart over your FIGHT button.
** Why were you even allowed to do that? Because you're playing by Sans' rules. He abused the rules of a standard RPG by taking too many actions in one turn (read: his final attack + his special attack), which gave you two turns in a row. [[DidntSeeThatComing Something he himself didn't expect.]]
*** Another reason might be that in the fight interface, every entity (human or monster) can use one attack per turn. It is not you who deliver the final blow: it's the Fallen Child, who never used their turn. This is confirmed by the fact that the killing blow isn't delivered via the player's actions — it just happens.
*** Starting from the second half of the fight after you ignore Sans' mercy plea, he begins throwing attacks at you in the menu. In this battle, you two are on equal grounds: both can attack and dodge attacks, both have (or did have) the option to Spare their enemy, and both can temporarily pause their opponent's attacks (to a certain degree) by staying in the menu and doing nothing. Sans tries to attack you in the menu; in the last moments of the fight, you do it right back.
* The final boss music of a No Mercy run is Megalovania, from ''VideoGame/TheHalloweenHack'', recycled music from another game (which is actually an ''VideoGame/{{EarthBound}}'' romhack with some similar themes). This works because the boss you're fighting is Sans, who is simultaneously [[BrilliantButLazy too lazy to bother coming up with his own theme]], [[MediumAwareness fully aware of your ability to save, load, and reset the world]], fights you by [[InterfaceScrew messing with the combat interface]] and [[CombatPragmatist shamelessly using hidden techniques nobody else can use]], and since he's a prankster, is trolling you by deliberately not using [[ExactlyWhatItSaysOnTheTin "Song That Might Play When You Fight Sans"]]. So reusing music from a hacked game is perfect here.
* During the final boss of a No Mercy run, after you finish off Sans, he'll ask Papyrus if he wants anything from Grillby's, which would be incredibly odd considering that to get the Genocide ending, you'd have to kill Papyrus. Why would Sans do this knowing his brother is dead? Simple, it was his way of peacefully accepting his fate. He said that he knew he couldn't beat you and his last resort was to cause a stalemate and prevent you from attacking; after all, with your high stats, you're basically an unstoppable force of evil that murders practially anyone who stops in its path. So after he gets hit and starts to leak all that ketchup he drank, he realizes he's taken a mortal blow and limps offscreen so you don't see him slowly die. Him asking "papyrus, you want anything?" was his way of finally giving in to his approaching death by mentioning his dead brother in the most calm way possible so he remains just as relaxed and cool as he was the entire game. Addressing Papyrus, whom is clearly dead, is him coping with the fact that he failed to stop you by talking to his deceased sibling as if he were making his way to the afterlife to join him.
** This, along with how he hobbles offscreen after defeat, is his way of making sure Frisk/Chara (who are, at this point in the game, a sociopathic mass-murderer) doesn't get the satisfaction of watching him suffer in his final moments. This fits, since the entire point of a No Mercy route is that it's unsatisfying and dull, with your only victories being hollow at best. Sans is by far the longest and most unfairly hard battle in the entire game, and when you finally get a hit in, he doesn't cry, lament his defeat, or drop his permanent grin. He just says "don't say I didn't warn you", climbs to his feet, and calmly staggers away, acting like you didn't just hand his ass to him.
*** Also, when he tells you "don't say I didn't warn you", he can only be referring to how he told you that if you went any further, you'd have a bad time. At the time of saying that, he seemed to be [[ThatOneBoss referring to the "bad time" he was going to give you]]. But the fight's over now and you beat him and yet he says "[[IWarnedYou don't say I didn't warn you]]". He wasn't talking about you having a bad time trying to get past him... he was referring to the fact that if you go any further, you're not going to be able to enjoy this game ever again without it being ruined (courtesy of Chara demanding your SOUL if you want to restart).
** During a No Mercy run, Asgore asks "What kind of monster are you...?" The obvious implication is that he's briefly mistaken you for one of his own kind, since it's commented several times throughout the game that you've ceased to appear human. The less obvious one is that [[WhatTheHellPlayer this statement is not addressed to the character]].
*** This is played with both ways with respects to the mirrors in Toriel's home (which gives the dialogue message "It's you!"), and New Home (which, on a pacifist run, gives the dialog "Despite everything, it's still you."). On a genocide run, however...
** In addition, after the Fallen Child is implied to kill you, it doesn't really add up that they can do that much damage when the main reason they were slaughtering people was because of how monsters worked. Then again, you kind of ''are'' a monster for taking this route to start with.
** Alternatively, at this point they're wielding an actual knife, and not an improvised weapon, so if they attack you, a human, it would definitely do fatal damage if they struck something vital (hence the infinite nines), and given what a freak they've become, the odds of them knowing where to stab to kill are pretty high...
** Though the Fallen Child's intention was to destroy the world. It would take an absurd amount of damage like that to destroy the world, and as a result, there is only blackness afterwards, even when the player returns.
* On a No Mercy run, during the fights with Undyne the Undying and Sans, to heal you're constantly stuffing food down your gullet as you take damage, usually really unhealthy foods like cinnamon bun(nys) and fast food. Pretty fitting for a gluttonous entity who wants nothing more than to consume the entire world in the darkness of nothing. Whereas the kinder-hearted Frisk rarely has to do so, and by the end can heal just with their determination alone in the fight against Asriel.
* The fight against Mettaton NEO on a No Mercy run is [[AnticlimaxBoss decidedly anticlimactic.]] With 90 ATK, this boss would kill you in two hits, regardless of what armor you're wearing. He never attacks; instead, he just stands there with his arms stretched out — according to the first text box, he's [[YouShallNotPass "blocking the way"]]. Mettaton NEO looks much more human-like than most monsters, and if you haven't killed everything before the confrontation, he concludes that you at least won't harm humanity; so while ''you'' wait for ''him'' to attack, ''he's'' waiting for ''you.'' He's waiting to see if you hesitate to hit something that looks like a human.
** An alternate reason for Mettaton's anticlimactic boss fight: In the No Mercy route, Undyne and the player both get their huge boosts in power from exceptional Determination, and Sans from some combination of determination and cheating. And if heart motifs symbolize determination, his NEO form is certainly designed to look like it fits the theme. But whatever positive traits Mettaton may have, determination is not one of them. In both routes, he doesn't want to fight you at first (in this route specifically because he doesn't want to die), and he only changes his mind for something that could be construed as selfish reasons. So despite all his bluster, he can't actually harness the one power that allowed Undyne to challenge you.
** Him not possessing this trait but attempting to make it look like he does is even reflected in the music... "Battle Against a True Hero" starts with a piano solo and builds into something incredibly bombastic and awesome. Since Undyne has determination for real, at the base of her character, this makes total sense. Mettaton's music? Similar, but jumps straight into the bombastic bit. At his core, he '''doesn't''' have determination, but he recites all the lines and rhetoric that might make it seem like he would.
** Another possibility is that Mettaton simply isn't made for combat. Everything he says about being originally designed as a human-eradication robot clashes with the backstory you discover for him in any other route, so the simplest explanation is that it's a bluff. He tries repeatedly to stall you with speeches and to get you to stop approaching him, and makes it clear that part of his reason for fighting you is to let Alphys escape. He knows perfectly well that you can kill him in one hit, but he's sacrificing himself (and using the one talent he does have, showmanship, to stall you with big dramatic speeches and a flashy encounter) in the hopes that that buys a little more time for Alphys and the others to get away.
* The message shown when you die to Asriel but automatically revive right away works as a StealthPun: it can mean either that Frisk's SOUL refused to give in, or that their SOUL ''re-fused'' back together from two halves.
** Similarly, determination is the power of unflinching resolve that persists against all odds. The word can also be read as "de-termination", which means ''negation of death.'' It is the in-game power letting a SOUL do just that. This double meaning aptly describes those who refuse to die, such as Frisk and ''the player themself''.
** The circumstances immediately preceding this confrontation bear remembering. One of the few songs on the soundtrack exclusive to the No Mercy run plays as Undyne rattles off a brief monologue before becoming Undyne the Undying. The track's name? "But the Earth Refused To Die."
---> ''My body… It feels like it's splitting apart. Like any instant, I'll scatter into a million pieces. But... Deep, deep in my soul. There's a burning feeling I can't describe. A burning feeling that WON'T let me die. Right now, everyone in the world... I can feel their hearts beating as one. And we all have ONE goal. To defeat YOU.''
** The game gives you the mercy of coming back to life every time your HP runs out...''[[MercyRewarded because you've been so merciful to everyone]].''
* One of the biggest complaints about the No Mercy path is that it can be very [[LevelGrinding grindy]] at times. That's part of the point. Some people aren't morally opposed to murder or killing under various circumstances. And many moral codes, including UsefulNotes/{{Christianity}}, posit that any deed, no matter how wicked, vile, or destructive it may be, cannot be considered a sin unless it was committed with full knowledge of the immorality of the act and the damage it could cause — accidental evil isn't ''true'' evil. ''Undertale''[='=]s No Mercy route works on similar premises. The encounters slow down the more you kill to illustrate that you, the player, are '''hunting them down and ''murdering them in cold blood'''''. If you [[ShootEverythingThatMoves simply kill everything you encounter]] without going out of your way to LeaveNoSurvivors, you get a neutral ending — there's still some room for the benefit of the doubt, that you could have been doing it in ignorance or self-defense. This makes it so that there is absolutely no way to get the No Mercy ending by mistake, or even by intention unless you're going about it knowingly (since even if you start on it, you can back out more or less at any time).
* The two non-Neutral endings have their own difficulties in obtaining them. The No Mercy route is grindy and has two [[ThatOneBoss bosses that are harder than anything else in the game]]. In a Pacifist run, you're likely to die a lot and might [[GuideDangIt have a hard time figuring out how to spare or befriend some monsters]]. However, anyone going through these routes can eventually make it past these challenges so long as they have [[ArcWords determination]].
* If you get a True Pacifist ending but ended up fleeing from some monsters instead of sparing them, or never encountering them in the first place, their outcomes listed in the credits are different (on top of them being in white rather than yellow, letting you know who you missed). Since you act as the main link between Monsters and Humans, you probably help everyone find their place in the human world, but if you didn't befriend them in order to spare them, you don't know them as well as you could and thus can't find them their perfect calling with what little you do know about them.
* When fighting Sans in a Genocide Run, he actively dodges your attacks and can effortlessly whoop your ass, and yet when Flowey attacks in the Pacifist Run, Sans is easily incapacitated. While this might sound like FridgeLogic, it makes sense once you realize that Sans' death in Genocide came from him not expecting you to attack twice. Chances are that when Sans realized Flowey was attacking, it was already too late to dodge.
* At the tail end of the "date" with Alphys, you're put into the same moral dilemma that you just had to help Alphys conquer — when Undyne asks if Alphys was joking about anime not being real (as in non-fiction) and asks you for confirmation, do you lie to keep her happy or be honest but break her heart? The choice might seem inconsequential in the short-term, and it's largely PlayedForLaughs, but considering that if you're on this date, you're likely on your way to getting the monsters to the surface, she's going to find out and have to deal with that paradigm shift eventually. Yet despite just teaching Alphys it's better to be honest up front, a lot of players are inclined to tell Undyne anime is real the first time through and not think twice (or justify it by telling themselves [[ExactWords it's real in the sense that it exists]], even though that's not what Undyne's asking). It's a lot easier to tell someone to be honest than to be honest yourself, isn't it?
** Another interpretation could be that, at least in the ''Undertale'' universe, anime ''is'' real. Think about it for a moment: the player character is a {{determinator}} capable of shrugging off death simply by refusing to die and finds themself in a world where both magic and monsters exist. The backstory speaks of an [[GreatOffscreenWar ancient war]] between the humans and monsters which eventually led to the latter being sealed underground for what was probably centuries at least. The final battle of the Neutral and Pacifist Routes involves the tragically villainous antagonist gaining the power of an eldritch abomination/outright godhood only to be bested by the [[DavidVersusGoliath seemingly inferior protagonist]]. A well-meaning, but misguided scientist ends up creating horrific (though largely harmless) chimeric beings due to her research into ways to overcome death [[GoneHorriblyRight going horribly right]], and also ends up creating the BigBad the same way. And then, of course, there's Undyne herself. While she may have been largely inspired by the anime Alphys showed her, she definitely fits the bill for a StockShonenHero. Oh, and there's time travel with all the [[TimeyWimeyBall complex goodness]] that entails. At this point, you aren't really lying when you tell her anime is real. After all, you're living in one.
*** Also, when you add the fact that seven ''wizards'' sealed the Underground, it's quite possible that there are still people with magic out there on the Surface. There could very well be massive animesque fights going on while Toriel bakes a pie.
* In one of the entries in the True Lab, Alphys writes that she has received five messages from Asgore: "four about how everyone is angry. one about this cute teacup he found that looks like me. Thanks asgore." This may seem like a strange detail for Asgore to tell Alphys in such a serious situation, until you think about how voicemails work — the latest voicemail is heard first. So Asgore, not realizing anything was wrong yet, called Alphys about the teacup and then began to hear everyone's grievances, and called Alphys to warn her. Alphys, going through her list of voicemails, would hear those messages first before arriving at the original one about the teacup, writing them down in that order.
* The idea that Frisk is a pacifist makes more sense considering their starting equipment, the Stick and the Bandage. Neither have bonuses to the traditional stats, but have alternate uses.
** The Stick is used in many fights to facilitate sparing the opponent, usually dog monsters, but can be used to spare Madjick, a late-game enemy, and Mettaton to gain a significant boost in ratings.
** The bandage can be used as a healing item, healing only 10 HP, which would be only useful in a Pacifist or otherwise low LV run. Also, if you keep it equipped, it lets you run away from fights on the first turn, something useful if you can't figure out how to spare a certain enemy, but don't want to kill them either.
* When you face Asgore at the end of a Genocide run, despite Undyne claiming that Alphys saw her defeat and would subsequently warn Asgore about you, Asgore is completely unprepared. Seems like a case of IdiotBall, but consider that Alphys probably specifically said that a dangerous ''human'' was approaching. When you meet him, Asgore asks what kind of monster you are — he doesn't recognize you as a human and therefore doesn't realize that you're the one Alphys warned him about.
* What animal are Toriel and Asgore based on? Goats. What (or who) plays an important role in their stories? Their [[{{Pun}} kids]].
** Additionally to the religious-based things above, goats are very important in multiple religions. They were often the most common sacrifice, being either the first or last step to get the gods' approval. Toriel and Asgore would be the first and last boss on your way to absolution (escaping the underground) if it weren't for Flowey.
* The KillEmAll route being called the Genocide run actually makes perfect sense — the player character becomes a monster by killing all of monsterkind. You're not only feeling right at home, but you're just doing the humans a favor. You are a monster, just like the ones you kill... but only in a [[SerialKiller vastly]] [[OmnicidalManiac different]] [[LackOfEmpathy way.]]
** It's also a reference to a style of play in another game: ''VideoGame/NetHack''. In ''Nethack'', if you kill enough instances of a species, it stops appearing during that run. Some players take it as a challenge to make this happen to as many species as possible. Like with the PacifistRun, ''Undertale'' takes an optional challenge and makes it canonical.
* Flowey derides those who choose to simply watch the events of a Genocide run as opposed to actually playing it themselves in his monologue leading up to the Genocide run's ending. Once more, [[ShutUpHannibal he's full of crap]]; it turns out through The Fallen Child's final victory, those kinds of players have a ''[[PermanentlyMissableContent very]]'' [[HeelFaceDoorSlam good reason]] to not actually go through with a Genocide run, and he suffers the consequences directly.
* If you choose to comfort Asriel by hugging him, you'll see a piece of dialogue that says: "I don't want to let go...". While many assume this is Asriel, one ''important'' detail that is often overlooked is that Asriel's face doesn't show up in this segment. [[SuddenlySpeaking This is Frisk talking.]]
** Alternatively, Asriel's face isn't shown in the box because Frisk is hugging him, and shielding his face from the player's view in the process. It's still Asriel's voice we hear, though; it doesn't seem right that Frisk would say "Ha... Ha..." before the rest of the aforementioned line. There's no reason for Frisk to be laughing like that at such a moment.
** There isn't any reason for Frisk to be laughing at this moment, but there is for Chara to be, if you interpret them as the narrator. The frequent references to Chara being a StepfordSmiler and [[CryLaughing laughing]] [[TearfulSmile away their pain]] in order to cope with traumatic or stressful situations could point to them being the ones laughing here. They finally get to reconcile with Asriel and embrace their adoptive brother after all they've both been through, and they don't want to let go.
** It doesn't seem all that implausible for Frisk to be the one laughing — if Asriel (or Chara, for that matter) could be doing it just from the sheer, overwhelming emotion of the moment, why couldn't they?
* In order to complete a True Pacifist run, you don't just need Determination, you need ''every'' mentioned trait.
** Patience: Not letting yourself get frustrated or aggravated with how other monsters treat you.
** Bravery: Taking the time to spare every monster can sometimes require you to face them longer than you would if you just attacked, so by putting the extra time and effort to spare them, you're not taking the cowardly way out.
** Perseverance: Enduring every harsh attack and word throughout your trek through the underground.
** Integrity: Never violating ThouShaltNotKill no matter how justified you'd be in fighting back in self-defense.
** Kindness: What you show to every monster.
** Justice: The run ends with you giving the monsters the fate they truly deserve.
* Consider the plot of the typical videogame-based {{creepypasta}}: Everything proceeds as normal until a certain point early on, after which the horror slowly but steadily increases, as the game does things that a veteran player has never seen in normal gameplay, often including {{Jump Scare}}s just for shock value, and the whole cast slowly getting psychologically broken or even killed, but not before warning the player they’ll have a bad time if they go further. Meanwhile, the music is generally replaced with dissonant noise and game text is changed to threatening or cryptic messages in red. As the experience goes on, it dawns on the main character that the game is [[TheFourthWallWillNotProtectYou addressing them directly]]. At the end, some malevolent spirit appears onscreen and inflicts a horrible fate on them. This is what the Genocide Route already is. ''It's an officially produced creepypasta.''
* In the Genocide route's FinalBoss, Sans turns your heart blue, making it control like a platformer game. Looks like [[{{Pun}} you finally understand the GRAVITY of the situation]].
** Why is your heart blue in this situation? Because you have to be ''patient'' and wait until the platforms cross the other side.

[[AC:Humans vs. Monsters]]
* With tough boss fights with crazy attack patterns like Undyne the Undying and Sans, you might wonder how the hell the humans managed to win the war against monsters at all when they have such powerful magic at their disposal. Then you might remember that your player character is a ''child''. The monsters' mightiest warriors can't even compare in physical power to a (admittedly very determined) kid.
* It makes even more sense if you take the in-game lore. The game outright states that a willingness towards violence automatically makes monsters weaker, or more accurately the violence against them more effective, and so trained soldiers, who may have spent their lives fighting other human enemies and honing a killing edge, would be able to simply stomp monsters in one hit, no matter how effective their attack patterns are. They just couldn't compete against an army of even semi-determined fighters.
** Especially considering the in-game lore mentions that not one soul was absorbed. Humans could have died of old age or disease, but were never absorbed. The Monsters didn't fight back, even in self-defense.
** It should be noted that Undyne, the underground's greatest active warrior, has a will to kill that makes her fairly unique among monsters, even more powerful ones like Sans and Asgore. She also seems to be the only monster to possess Determination. Despite her FantasticRacism, she became monsterkind's hero by expressing [[HeWhoFightsMonsters human qualities]].
* If the war was so one-sided in the humans' favor, why didn't they just wipe them out? If the monsters couldn't claim a single human soul, then there was absolutely nothing preventing the humans from inflicting genocide. Perhaps humanity as a whole decided to use the "Mercy Option" when deciding to seal them away instead?
* It might seem odd that humans would just ''forget'' about monsters — surely they'd leave a few pretty damning clues behind about their existence! Until you remember that when a monster dies, they turn to ''dust.'' There would be no fossils or physical evidence at all of their life!
** And any kind of documentation of monster society could have either been weathered away over the years, destroyed, lost, or simply dismissed as myths by modern historians. It looked like the war took place during the Middle Ages, which ''do'' have a reputation for, among other things, being highly superstitious.

[[AC:Yet to be Sorted]]
* Why does the player get a flashback to Asriel meeting the First/Fallen Child after Undyne sends them falling into the garbage dump? Look what you landed on — golden flowers. They more than likely came from the seeds infused with Asriel's remains.
* Another interpretation of this flashback is that the long fall triggered the First/Fallen Child's memory of falling into the Underground, where they met Asriel.
* One of the descriptions that displays during the True Pacifist final boss battle is "The whole world is ending." This is technically true, but not because of anything the boss is doing — once this fight is over, the game is over, and you'll either leave or reset it.
* The Fallen Child's claim that a demon comes when you say its name could be literal, referring to the prompt at the start of the game. But that doesn't ring true because you always have to do that step but it doesn't always gain any power. But it could also be metaphorical, in that you invite it to join you, by intentionally killing everything and pursuing the No Mercy path. It's always there waiting for you.
** Considering [[https://twitter.com/fwugradiation/status/643945593308618752 the main developer suggests that you name the Fallen Child after yourself]], it may go deeper than that. Every time that you use the same name, seeking power for its own sake and destroying senselessly in ''any'' game, you may be summoning them.
*** Or alternatively, that the developers try to suggest that [[InYourNatureToDestroyYourselves this desire to kill everything might be dormant in every single one of us]]. We all could end up in a mentality of "kill or be killed", and unless we make a concious effort to be kind to others, we might become something that will even frighten a monster.
*** On a similar note, the First/Fallen Child gains enough power to be able to move on their own because it's their name on the save file that lists the stats you earn, not Frisk's!
* Also, the line in the First Child's ending speech in the Genocide route? "Let us erase this pointless world, and move on to the next." They're not just remarking that the world doesn't have meaning anymore — it's literally pointless. There are no more points left to earn in the game, because [[YouMonster you've already killed every monster in the Underground.]]
*** [[https://www.reddit.com/r/Undertale/comments/3rqzd8/i_dont_believe_chara_is_evil_and_neither_should/ Maybe you guys are judging Chara a little too harshly...]]
* The game's view on violence is actually a bit more nuanced than one would think. Sure, for the player, it always works out that mercy is better in the long run than fighting, and the few times throughout the game that you don't get the chance to be merciful initially, you do eventually get the chance and it does help, but for the [=NPCs=], it's not necessarily the case. If the player decides to kill everything, no amount of mercy will necessarily help. Instead, the use of force to stop the player's rampage is presented as genuinely heroic. It's even possible that the threat of getting beaten down by the two toughest bosses in the game will dissuade players from going the evil route.
** One of the bosses even tries to use Mercy ''on you'' during a No Mercy run: Papyrus. At this point, whether the game's original message still holds or not depends on whether you're heartless enough to kill someone posing absolutely no threat to you, and since many players abort their No Mercy runs when they face Papyrus, his method might be [[HeartwarmingInHindsight just as effective as Undyne's and Sans' brute force]].
*** You also ''have'' to get past Papyrus on the No Mercy route (read: '''kill him in cold blood''') to even ''get the chance'' to face Undyne the Undying and Sans. In other words, [[ViolenceIsTheOnlyOption force can indeed become the only option when dealing with those who adamantly refuse mercy.]] It's a similar position as Asgore: even if you've never attacked anyone the entire game, he makes it absolutely impossible to show him Mercy and still get where you're trying to go. You have to fight him to progress. For Undyne and Sans, you've effectively just shattered the Mercy button – to get where ''they'' want to go, they have to fight ''you'', too.
* Crosses over with FridgeHorror slightly, but as you progress through the game, the major characters you befriend start showing up on the save screen and more instruments fill in the initially simplistic theme. But once you've completed the True Pacifist route, everyone's gone to the surface, leaving the screen devoid of even your close friends. The only thing giving you company is idle ambient noise of a somewhat eerie variety, symbolizing that the entirety of the underground may as well be one gigantic pit no one ever wants to visit again. Well, no one except you, should you True Reset, [[YouBastard remove everyone's happiness, and start over from mostly scratch just to fill the void again]].
* Mettaton NEO has unique music, a drastically different appearance, and... dies in one hit on the No Mercy route. Looks like the battery wasn't on the list of upgrades he got.
* From a meta standpoint, the fact that so much of the game is hyper-aware of things like hacking and datamining makes sense when you consider that Music/TobyFox's early game-making experiences were hacks, in particular [[VideoGame/TheHalloweenHack the EarthBound Halloween Hack]].
** There's also how the game was made in [=GameMaker=], an engine where everything is stored in easily-opened formats.[[labelnote:*]]All textures are .png files, all sounds are .ogg files, and code is stored in plaintext that isn't compiled or obfuscated in any way.[[/labelnote]] Looking into the game's resources doesn't require serious programming knowledge, so any secrets that can only be obtained by looking through the files can still be seen first-hand by a lot of people.
* At first, Undyne's whole spiel about 'everyone's hearts beating as one' might seem like a classic cliché shonen anime line, but on second glance? That's ''exactly'' what it is! Undyne all but ''worships'' the anime that Alphys digs up like gospel, so of course that's where she got a majority of her ideas on her whole 'warrior' persona from! She's trying to be as shonen as she possibly can!
* When playing the Genocide route, examining mirrors and the like gives messages like "It's me, [name]". On Neutral, you get messages like, "It's you". In the Pacifist route, people learn the true identity of the player character and refer to them more explicitly than at other times. It's a play on the first person, second person, and third person points of view. The No Mercy route involves a complete takeover of Chara/a complete unification of Chara and the Player's determination. The Neutral route involves [[MultipleEndings varying degrees of cooperation]] between Chara, Frisk, and the Player. The Pacifist Route involves complete cooperation between Frisk, Chara (if you believe the narrator Chara theory), and the Player, ending with Frisk moving on to live their own life.
* Why is the stat that measures your potential for hurting others [[FunWithAcronyms abbreviated as]] LOVE? How hurt would you feel from an ''emotional'' perspective if [[GenocideFromTheInside one of your loved ones tried to kill you?]]
* It's said that Gaster was torn through time and space when an experiment went wrong. If you go into the files, you can change a value that adds several unused characters to the game. One of these characters is a distorted creature that looks similar to [[VideoGame/YumeNikki Uboa]] and is thought to ''be'' Gaster. [[http://i.ytimg.com/vi/A5WMip_XwL8/hqdefault.jpg A scientist that takes a form similar to Uboa]], [[VideoGame/TheHalloweenHack where have we seen this before?]]
** This is probably an unintentional but most likely intentional move by Toby. Gaster was mentioned as torn through space and time. He is not dead but he is still alive. They are actually right. The time and space location is where the files of Gaster are kept in. The very location where he ended up in due to an experiment gone wrong. And on an unrelated note yet still involves Gaster, his leitmotif sounds eerily similar to ''Final Fantasy VII''[='=]s [[https://m.youtube.com/watch?v=6CmV2ev09h8 Who are you?]]. A fitting title too as we, the players, like a majority of the monsters, do not know who Gaster is.
* Whenever the player character dies, the representation of their SOUL splits in two. They die of a broken heart.
** This can be seen as terrifyingly bad for the monster that kills the player character. They just destroyed one of the final potential pieces needed to escape the Underground, and who knows how long it would be until another human fell down. Well, until you reset.
* The bit under Fridge Horror about how much the plot is reliant on Flowey being present veers into this when you realize that him begging you to do a True Reset is actually a BatmanGambit on his part; Asriel is asking you to make him forget because he's aware Flowey is the reason breaking the barrier was even possible. Thus, he's willing to sacrifice his memories for the chance that you'll eventually bring everything back to the GoldenEnding again.
* Going through the underground, you might notice that all the monsters that are a threat are ones that fight at range, either through magic or weapons with a long reach (in Undyne's case, a combination of the two); this makes sense as something that would help even the odds in a fight against a human, since getting within melee range can be instantly fatal even if they're only attacking with their bare fists.
* Why does Sans use so many blue and gravity-based attacks in his fight? Well, think back — who's the first boss to use gravity, or "blue " attacks? Papyrus. Of course Sans is going to use them a lot — either he originally developed the move and acted as a StealthMentor to his brother, or his brother ''actually did'' develop the technique first, and Sans thought the technique was the coolest thing in the world. Knowing how much Sans loves his brother, it's not too far of a stretch for Sans to have taken Blue SOUL techniques to the absolute limit as a way of remembering him. Also, as LaserGuidedKarma for killing the person he cared for most in the world.
** He doesn't just use the same mechanics. Many of his attacks are literally upgraded versions of Papyrus's attack patterns, with additional hitboxes, smaller gaps, or faster speed.
** On the No Mercy route, Papyrus never even puts up a fight — he literally will not attack you, and you will kill him in one hit. The only way to actually experience his BossBattle — and his Blue SOUL mechanics — is to play on the Neutral or Pacifist route. So if you were stupid enough to do a No Mercy run before anything else in the game, Sans's Blue SOUL mechanics will come from completely out of nowhere and most likely [[DidntSeeThatComing catch you utterly off-guard]] — and the way Sans' fight works, being caught off-guard means you're dead in about two seconds at the ''most''. [[LaserGuidedKarma Which serves you right for sweeping Papyrus aside like mere garbage.]]
* Why does Toriel show up during the True Pacifist Ending, when visiting the True Lab doesn't actually change anything relevant to her? Actually, it does. If you visit the True Lab before fighting Asgore, it gives her much more time to rethink her decision and set out after you.
** This was even foreshadowed at the very beginning of the game. During the combat tutorial, Toriel told you to stall for time, and she will come to resolve the conflict. By visiting the True Lab, you're stalling for time so Toriel can rethink everything and go after you to New Home, and it pays off when you encounter Asgore. Toriel does come to resolve the conflict by blasting Asgore away.
** It makes sense in the Neutral run as well, where she returns in the ending. Maybe she rethought her decision and came after you, but was a little too late to get to you before you got to Asgore, so she didn't arrive in time to prevent the fight, and arrived at New Home after you left the Underground, hence why she is Queen if spared in the Neutral runs, albeit sometimes only for a short while.
* During the date/hangout with Undyne, there's a scene where she tells you to project your worst enemy onto some vegetables and then punch them. You then have the option to pound "strong" or "wimpy". Selecting "wimpy" makes you pet the vegetable — something you truly would do to your worst enemy on a pacifist run, given the chance.
** Alternatively, selecting "Strong" merely results in you pushing the vegetable over. As a pacifist, you're unable to muster any strength to fight.
* Why is New Home so grey and lifeless-looking? Imagine yourself as a father of two, with a loving wife and hope for the future. Now imagine you lose both children in one night, make a rash promise in great anger, and accidentally drive away your wife, who leaves in disgust. You're now alone with the responsibility to continue forth with your anger-made promise, alone, against your very nature, all to try and give hope to the grieving masses. A long, slow plan that, while it does move closer to fruition, every death from it is entirely ''YOUR FAULT''. [[ItsAllMyFault At least in your own mind.]] It's any wonder Asgore can even do his daily activities... but then again, that [[StepfordSmiler might be how he stays sane]]. The color left New Home the second Asgore's loved ones did.
** Especially when one examines the sink. Why is there so much fur in the drain? Because Asgore uses it to wash his face so nobody will see that he was crying.
* No matter how many major characters you kill, Sans will only fight you during a No Mercy run. Why? That's the only path with irreversible effects, namely that ''the True Pacifist ending is no longer obtainable''.
** Even then, he's reluctant to fight you, and puts it off to the last minute in hopes that you'll turn back. Why wouldn't he be? Killing you permanently is impossible. But when you are literally two empty rooms away from dooming the timeline, he can't afford to stay on the sidelines any longer.
** So instead of trying to fight you, even when you're being evil, he takes the much more sensible route of constantly checking up on you throughout the game. He plays harmless pranks, tells jokes, invites you out to eat twice... Sans does everything in his power to make you like him and think of him (and by extension the other monsters) as a person and a friend. And oh yeah, tries to make you feel extra guilty about possibly killing Toriel while he's at it. Except... even he can't bring himself to put on a smile and act like your friend if his brother is dead.
* It may seem like Sans is being his usual self when he tells Papyrus you'll never be able to solve his [[http://vignette3.wikia.nocookie.net/undertale/images/0/0a/Asd.png/revision/latest?cb=20151014223140 word search puzzle...]] but [[UnwinnableJokeGame you actually]] ''[[UnwinnableJokeGame can't]]'' [[UnwinnableJokeGame solve it]]. At first glance, most players assume the nonsense word "giasfclfebrehber" is just the top row of the puzzle, but the top row instead spells out "giasfclf'''u'''brehber". (It also works on the meta level, because there's no way to select the words, so the player ''has'' to walk around it.)
* New Home:
** Off to the side in New Home is a row of coffins marked with color-coded hearts. You can only reach the red one, on the far left, which is marked with the name associated with the save file. It's empty, presumably to contain the player character. Except that the name it's marked with ''isn't the player character's,'' it's the Fallen Child's. Examining it will also reveal bandages that remind Frisk of mummy wrappings. Where did the body inside go, and why is it marked the "wrong" color?..
** Talking to Flowey in the No Mercy route reveals that Toriel took the body and gave it a proper burial under a certain patch of flowers.
** The opening with a child (we never see their face) climbing Mt. Ebott takes place in "201X". Toriel has an "old" calendar that's labelled "201x." That's not Frisk we see falling in the opening, that's the Fallen Child.
*** Confirmed in the No Mercy route, by the Fallen Child, as "The day I came here."
** If you look at the shirt of the person in the opening, their clothes don't match up with Frisk's; there's only one stripe on the shirt. They ''do'' match up with the shirt that the Fallen Child wears in flashbacks and the Genocide ending.
* Why is it that after a True Reset, you need to earn a Neutral ending again before you can acheive the Pacifist ending? Because the aforementioned ending isn't just caused by the player's (or Frisk's) actions — it also hinges on Flowey's actions. Actions which he only takes in response to being defeated in the Neutral ending. So he suggests to Papyrus that Undyne give you the letter, and then lures you to the True Lab, to buy him time to gather everyone in one place.
* When you first meet Sans, he mentions that he "doesn't really care about capturing anybody." Considering his demeanor, the line just seems to be establishing his laziness. Later on, however, you learn through a conversation with Sans that perhaps he's not so keen on taking prisoners in the first place...
* Choosing the "*Joke" option while fighting a Woshua will lead to several "dirty" jokes about two kids playing in a muddy field of flowers, a kid eating pie with their bare hands, and a kid who slept in the soil. Seems innocent enough... until you realize that the jokes are referring to Asriel and the Fallen Child. [[DudeNotFunny And the Fallen Child is, indeed, sleeping in the soil.]]
* In Grillby's, one of the patrons states he's put out a line looking for fish to date. It seems strange, until you realise the entire town of Snowdin seem to respect and adore Undyne as their protector, and later Undyne is revealed to be a fish-person — no wonder that guy would want to find others that resemble the town's admired guardian.
* Alphys used to be close friends with Bratty and Catty — together, they formed an ABC-themed group.
* Mettaton gives you extra points for complimenting his legs in the essay, and uses some leg-based attacks. As either a ghost or a box-on-wheel robot, he has never had legs before, so of course he is excited about them!
* Each of the human [=SOULs=] is a different color representative of certain actions or effects your SOUL is put under, each one shows signs of having died along the way because their souls weren't as malleable as yours.
** The Light Blue SOUL died in the Ruins, before Light Blue attacks start appearing; presumably they just stayed where they fell until a malicious monster found them and took their life.
** You find the orange human SOUL's equipment in Snowdin, where one can assume they died. We're also introduced to light blue attacks here, where so long as you stay still, you'll avoid damage. The orange human SOUL was described to always be rushing forward with their attacks (orange attacks are avoided by moving through them), so more than likely they died by running through too many blue attacks.
** The dark blue SOUL's equipment is found in Waterfall. Certain monsters in Waterfall, such as Aaron, have attacks that are sparse at the top of the hitbox, but tend to clog up the bottom, making it very easy to take massive damage if one gets trapped. When blue, your SOUL is restricted to the bottom of the hitbox and can only jump straight up and down or leap over things.
** The Purple SOUL could be one of two reasons, it seems like they were a studious note taker and that's what got them so far, but you buy their equipment from Gerson before two rooms that have poor visibility; presumably they couldn't take notes since they couldn't see to write. Another factor is that among the monsters you encounter in the dark rooms are [[CloudCuckoolander Temmie]], so note-taking probably wouldn't be effective anyway.
** The Green SOUL's equipment is found in Hotland, where orange attacks are introduced. Green can block projectiles, but is completely immobile, and Orange attacks require you to move through them. Also, most attacks in Hotland cover the entire screen or flank from multiple sides, so only being able to block one direction wouldn't have helped them.
** The Yellow SOUL could have died in either Waterfall or Hotland (Bratty and Catty say they found a gun in a dumpster, not in the dump). If the former, then like the dark blue SOUL, they wouldn't have any counter for the massive amount of attacks that pool at the bottom of the screen. If the latter, then they probably died when they ran out of ammo; crack shot or not, they were far in their journey with their only offense being a limited resource and had over-reliance on it.
** The remaining mystery is the Red SOUL, which is not specifically defined in-game, aside from a single line: "RED: Try as you might, you continue to be yourself." Being yourself — being genuine, sincere, and following what's in your heart — comes up elsewhere in the game. Or, to put it another way, if you have a Red SOUL, then you have a strong "Chara"-cter.
* Related to the above point: Each time the SOUL colors appear in game, they invoke that aspect both in gameplay and in story:
** Light Blue (Patience): It's very easy to get jumpy when seeing an attack coming your way, so you naturally move, thus you didn't have the patience to wait and see. This also comes up in the story, seeing as Snowdin will feel rather long for a first-time player due to the shortness of the ruins.
** Dark Blue (Integrity): The SOUL is now bound to the ground, putting it on the same level as the attacks, thus they are made equal. This is also shown in the two people who use them: Papyrus, who ultimately cannot kill you whatsoever, so there is no reason to kill him. And Sans, who is punishing you for your lack of intergrity.
** Green (Kindness): During your adventure in Waterfall (and slightly beyond), you come across the choice of either saving a character or leaving them to die. This also comes up in battle against Undyne: She has given you a way to defend yourself and you must find a way to avoid killing her (despite her being technically [=unSPAREable=]).
** Orange (Bravery): This is the final steps of your journey, where you either die or be free. You can turn back and just live in the Underground...but you gotta press forward. Same in game: Gotta be brave to rush into an attack. This can also apply to Alphys, who never actually encounters a single attack and lacks Bravery.
** Purple (Perseverance): When you get trapped by Muffet, your movement gets limited yet again and you cannot flee, thus you have to fight. And the best way to defeat her is to simply learn all the attacks and curveballs. Also shown as the upcoming part is one of the hardest in the game.
** Yellow (Justice): Before, Mettaton was letting you win against him, but now has betrayed Alphys and attacked you to protect humanity. Now you must show him the error of his ways and win in a proper fight. Just as well, Justice is usually associated witb law enforcement or guns and the Yellow mode shoots bullets.
* Most of the major monsters represent one of the same qualities as the human [=SOULs=], though not necessarily matching up with the color associated with their respective areas:
** Toriel represents Patience. She is understanding and maternal, accepting of your quirks and foibles until you force her hand. She could also represent Integrity, considering she's unwilling to compromise her ThouShaltNotKill ideal, even at the cost of her leadership or her people's morale.
** Papyrus represents Perseverance. He keeps training and trying to join the Royal Guards, trying to prove his worthiness to Undyne.
** Undyne represents Bravery, especially in a No-Mercy Run. She directly challenges the child, even if they've proven to be a ruthless killer, knowing she might die.
** Mettaton represents Integrity. Though he initially follows his programming to kill humans, in a Pacifist Run, he reveals that this was not what he was built for, to the point that he exposes his "killer" programming was a ploy by Alphys to [[ManipulativeBitch prove herself a trustworthy companion to the child]], and that he wants to stop Asgore's war against humanity, in order to protect humanity from him. In a No-Mercy Run, he wants to stop the murderous child from hurting anyone else. He could also represent Patience, considering how many slip-ups on Alphy's part he has to tolerate and work around to keep the ruse going.
** Asgore represents Kindness. Despite his declaration of war against humanity, everything you hear about him from the denizens of the underworld, and his behavior once you meet him, indicates he is a "big fuzzy goofball."
** Sans represents Justice. When you meet him in the Last Corridor, he will judge the child on their actions taken through their trip through the underworld. And on a No-Mercy Run, He will attempt to enact justice on them.
** W.D. Gaster represents Determination. Throwing himself entirely into his work, willing to go to any length and break any moral or ethical boundary to see his goal achieved, and ultimately surviving being sundered across space and time, slowly clawing his way back into reality again.\\\
Alternatively, [[https://www.reddit.com/r/Undertale/comments/43paux/why_the_human_souls_represent_what_the_main_6/ it could be the other way around,]] with each soul representing something one of the core 6 monsters ''lacks''.
** Toriel lacks Patience with her ex-husband's way of thinking, as well as bringing Frisk through the puzzles (note that she changes her mind about letting you solve one).
** Sans lacks Perseverance and always lazes around as a result.
** Papyrus lacks a sense of Justice because he wants to befriend you regardless of how murderous you've been.
** Undyne lacks Kindness — even her befriending attempts are hostile.
** Alphys lacks Integrity as she was unwilling to own up to her mistakes and thought it better to keep everyone happy via lying. If you want to keep Mettaton on the list, you could argue that he lacks Integrity too, due to breaking his promise to not leave Napstablook.
** Asgore lacks Bravery because he wasn't willing to go the quickest, most painless route towards his goal, nor was he willing to back out of his plan despite his misgivings.
* One thing you may notice between the Ruins and New Home is the bedroom. The bedroom in the Ruins only has a single bed and a bunch of stuff that would have been collected over the years. New Home, by comparison, has two beds, for the Fallen Child and Asriel, and seems to be kept in a state like they still lived there. This is odd since the game states outright that the Ruins were abandoned and New Home built only after the two died, but it represents how the parents dealt with the loss. Toriel has moved on completely and remodeled the room to focus on the future, keeping children who fall down safe, while the bedroom in New Home is the way it was because Asgore still hasn't let go of the pain of their deaths (he even has a calendar, marked on the day they presumably died); even though he desperately wishes to move on, forcing himself to remember what happened to Asriel and the Fallen is the only thing that keeps him going.
* A True Pacifist run not only requires the player to sheathe all instincts to take the offensive in a fight, but also to befriend each of the bosses you meet. In hindsight, this makes a lot of sense when you realize each character's deficiencies:
** Toriel is a mother who has lost two children, and tried to save countless others from venturing into the underground. When going a Pacifist route, you have to convince her to let you go on your own, even though she wants you to stay and eat pie, and before giving you a hug tells you not to come back. She's stuck in the state of reliving Asriel and the Fallen's death by letting you go, and finally gets out of that cycle by following you, to protect you from Asgore.
** Papryus in all honesty is a MinionWithAnFInEvil while wanting to prove himself by capturing a human, but is a real softie. When you offer friendship or flirtation, and he realizes that you are not an evil human, he immediately switches gears to win your friendship.
** Undyne is a more competent warrior than Papyrus, and trained to take down humans. When you pour water on her in the Hotlands and save her life, she not only has to change her perspective, but manage her wounded pride that a bit of overheating nearly did her in. Plus, as a proud warrior, she more than likely is stuck between believing she is protecting everyone from a threat and now owing you her life (a serious thing in almost every kind of military). Going to her house and cooking with her shows her soft side, and she takes on the challenge of friendship when Papyrus suggests she can't handle friendship.
** Alphys is complicated in three ways: one, she is a LovableCoward about her crush on Undyne, two, her attempt to be the hero in your tale, and three, her part in creating Flowey and the Amalgamates. Thus you have to go after her when she runs off crying when Mettaton runs out of batteries and show her that you like her despite the lies and experiments, as does Undyne.
** Mettaton is a charismatic TV star for the underground, and enjoys entertaining. By refusing to hurt him, even when he changes into his human body, you give him time to listen to his viewers who want him to stay, including his cousin Napstablook.
** Asgore in all versions is a BigGood who made a bad decision in a fit of anger and grief, and who being HonorBeforeReason will fight you no matter what you do. Toriel in the True Pacifist Ending giving him a DoWrongRight lecture brings him back to his senses, and allows him to shove aside his past in favor of redemption.
** Sans has been watching you to see if you are going to start killing everyone and if he has to break his vow to Toriel. When you show that you haven't killed anyone, and have even been comforting his brother, he's happy to reveal the promise he made and how relieved he is not having to watch his friends and family die.
* Asgore's theme is literally just titled "ASGORE." As you may have noticed throughout the entire game, Asgore is ''terrible'' with names. This probably extends to his own theme as well.
** Likewise, Sans' theme, just called "sans." because he couldn't be bothered to name his theme.
* The final boss of the Neutral ending, Photoshop Flowey, is naturally fought to a remix of his leitmotifs: Your Best Friend, and You Idiot. The composition is creepy and oppressive to reflect the fact that you're struggling to survive an impossible battle against a god, until the final stage of the fight. At that point, the music becomes brassy and triumphant to symbolize your upper hand. Except that whole stage of the battle is actually an example of Flowey trolling you. Finale being another remix of his theme is a hint that Flowey is still in control — he's just ''letting'' you reduce his HP so he can crush your spirit. Notably, the sequences in which the six [=SOULs=] break free of Flowey and you decide how you're going to deal with him have ambience but no actual music. (Of course, by the time you've freed the [=SOULs=], Flowey has already lost, since they're how he was able to save his files in the first place.)
** Similarly, this is why [[AntiClimaxBoss you can withstand a surprisingly generous number of hits]]; he wants you to think you have the upper hand so he can savescum your victory away. Afterwards, he slams you with a bunch of OneHitKill attacks, reloading after each one, to show you that he could've done that at any time, but chose to hold back and lull you into a false sense of security.
* Asgore seems like a walking SatanicArchetype, between the [[ProngsOfPoseidon weapon he uses]], mythology surrounding him, and goat-like appearance, but it becomes clear within ten seconds of meeting him that ''none'' of them are applicable to him as a person. That in mind, recall that Monsters existing with humans was fact that turned into myth with the passage of time, it's incredibly likely that over the years, humanity took a measure of WrittenByTheWinners and, requiring a {{designated villain}}, that any religions that formed probably used him as their devil figure as an attempt to demonize the monsters further and justify the fact that they were the ones that started the war. In other words, he doesn't fit into a Satan-like role, but the Satan-like role was created around him.
* According to EasternZodiac compatibility, [[http://www.sunsigns.org/chinese-rabbit-dragon-love-match/ the Rabbit and the Dragon are both compatible to each other]], although they're TwiceShy about it at first. Now, what animals do the Royal Guards resemble?
** Disregarding their actual personalities contradicting their expected zodiac personalities, and assuming that [[SempaiKohai RG01 is a year older than RG02]], or the latter is at least a decade older than the former, [[WildMassGuessing it might be discussed for another speculation]]...
* Bratty and Catty are found in an alley. Bratty is an Alley-gator, and Catty is an Alley-cat, while both act like V-alley girls.
* Overlapping with FridgeHorror, it makes a lot of sense that you [[TheUnfought can't fight [=Chara/The Fallen Child=] directly]]. In No Mercy, they simply [[GrandTheftMe take control away from you,]] but even if you were to transplant another Frisk from a different timeline into the run, what could they do? You can't just [[TalkingTheMonsterToDeath use Mercy on them]]; Papyrus already tried that, and look where that got him. Chara has no qualms killing another human, and with no combat experience whatsoever, pacifist!Frisk wouldn't stand a chance against Chara in a fight. Even neutral!Frisk probably isn't ruthless enough to stand up to Chara, [[LevelGrinding who is at max-level]] [[InfinityPlusOneSword and has top-level gear]] [[GameplayAndStoryIntegration simply because of how No Mercy works]]. You not only handed Chara your SOUL, but also [[NiceJobBreakingItHero the perfect vessel to commit omnicide with.]] Any confrontation with Chara would [[HopelessBossFight end in a losing situation,]] so the game doesn't even let you try. The only way to truly beat them is to deny them the opportunity to fight in the first place... which is exactly what the True Pacifist run is all about.
* Why are you stuck in a dead void after your first No Mercy run, when up until that point you could just reset? And how does Chara bring the world back after you sell them your SOUL, anyway? Turns out both questions have the same answer — Chara is more determined than you now, so the one with the power to reset is them, not you.
* In Genocide, every boss fight other than Mettaton Neo seems to involve a MoralEventHorizon on its own — Papyrus and Muffet decide to spare you from the beginning, Toriel was going to raise you as though you were her own child, and Undyne intervenes when you attack Monster Kid. Yet, the only way to lock yourself on this path is if you've eliminated every monster prior to fighting Mettaton NEO. This seems to reflect the idea that one simple action does not make someone good or evil — even if you show mercy, you still have to live with the consequences of what you've done up to that point, after all — and it's never too late to reform if you really want to.
* The prophecy talks about an "Angel". This is very appropriate, seeing how both Asriel and Chara need to come BackFromTheDead in order to fulfill the prophecy.
* During the FinalBoss fight of the PacifistRun, the background goes crazy. This may seem like just a neat effect, until you realize you're still in the barrier, and it's reflecting Asriel's rainbow trail.
* [[EtTuBrute "Et tu, Toriel?"]] is the reaction many players will have when she says she'll destroy the exit of the Ruins, and this puts the "Tutorial" {{Pun}} with her name [[HurricaneOfPuns into a whole different perspective]].
* The fountain in Mettaton Resort is the Royal Memorial Fountain, built 201X (Mettaton Added Last Week); considering what royal tragedy we know happened in 201X, it was probably originally a memorial for Asriel and Chara. The original statue can be found in Waterfall. It looks like the monster type that Asriel, Toriel, and Asgore are and starts to play a musicbox variation of "His Theme" when being given an umbrella.
* All throughout the game, people hammer in the point of "you're a monster if you kill because you can just as easily spare them". To some, this rings hollow because you're usually defending yourself if you kill, but in reality they're right, because you put equal amounts of effort into killing as you do sparing. How long do most fights generally take if you spare? Optimally, three turns, the first to ACT, the second to dodge the enemy, the third to spare. How many turns do they go if you choose to kill them? Optimally, three, the first hit (if critical) takes off the greater part of their health, the second is to dodge their attack, the third to finish them. Unless you've ground on enemies enough to come one or two kills away from triggering the Genocide run's criteria, fights are equally as long regardless of your path, there's literally no pragmatic reason why you would fight instead of show mercy.
* Why exactly did Toriel block Undyne and Alphys' first kiss despite everything you have experienced in the Underground? Note how she says "the human" instead of "the child". Perhaps it's because you are a human, a race of beings [[BuryYourGays who have systematically hurt and killed people who have relationships of two men or women]], even some of the nicest people have in history. She wasn't preventing loss of innocence, she was protecting them from being hurt by you [[HeteronormativeCrusader overreacting]] out of disgust or offense. Sure, humanity is a lot more tolerant now, but with how little of human culture monsters know outside of what flows into a trash heap, they wouldn't have any way of knowing they've moved past homophobia being an acceptable standard.
** Especially considering the only two characters who would know it's more accepted now are, well, Alphys and Undyne.
* Why do you see a Real Knife by the end of the game on a Genocide run instead of the usual Worn Dagger? It's because outside Genocide runs, the PC sees it as a tool, something you use, whereas the murderous Chara would see it as something made specifically for ''killing'' things. Plus it's the only thing that isn't a toy, a tool, or a piece of clothing — none of which are made ''just'' for killing. Further supporting this is the item description, depicting its use for non-combat and combat means and the difference in the attack stat. The 99 ATK "you" think you can do is due to Chara's proficiency with actual weapons rather than toys and common household items.
** Alternatively, the 99 damage comes from the Fallen Child's ''perception'' of the knife, since with monsters, you do as much damage as you think possible. Naturally this wouldn't work for humans like Frisk, but it still is a potentially deadly knife when used by a knowledgable person.
* On the subject of the Worn Dagger, the last weapon you receive on the neutral and pacifist routes, its item description reads "good for cutting plants." Your final boss for the neutral run is Flowey — a plant.
* Why does Chara have to describe everything? Frisk's eyes are closed or squinted for whatever reason. Frisk has poor eyesight, apparently.
* If you, during a Neutral run, only kill beings in the Ruins, Undyne still calls you out on having killed monsters. How on Earth could she know that? The Ruins have been sealed off from the rest of the underground for ages, no-one has been able to enter or exit them for ages (well, except for incorporeal beings like ghosts and burrowing beings like Flowey), so no-one could've told her about it, riiight? ... Do you remember who else is aware of what you did in the Ruins? The Mad Dummy, Undyne's personal and very chatty training dummy and the cousin of the ghost / dummy you meet in there. Do you remember emo's neighbors with Undyne? Napstablook, who, if you do a Genocide run, escapes as you approach them, proving that even though they're just lying there, they are ''very much'' aware of what you're doing in the Ruins. With that in mind, is it ''really'' so very odd that Undyne is well informed about your actions in the prologue?
* The battle with Photoshop Flowey provides hints on how the FinalBoss Battle with Asriel Dremurr in the PacifistRun will play out: you spend most of the time dodging the attacks, unable to talk or act except to call for help, and potentially trapped in an endless loop of playtime with Flowey. The intense battle scenes alternate with your SOUL encountering the items from the previous dead children, which turn into healing items when you ask for help. Eventually the six children's souls come together to help you in rebelling against Flowey, destroying his power from the inside out. And what do you do in the FinalBoss Battle of a PacifistRun? Enduring Asriel's attacks until you can call out to the monster friends you made during the game, to SAVE them. Before, with Photoshop Flowey, you are SAVING the souls by reminding them of who they were, what they liked, and what they carried. This makes the decision to spare Flowey all the more significant, since if not for his hint, you cannot complete a true PacifistRun.
* I think the most overlooked bit is that most people usually get the meaning for Toriel's name but wonder why the player/Frisk can't call Toriel anytime after they leave the Ruins. Well, ''who goes '''BACK''' to the tutorial after they finish it?''
* The battle against Undyne looks a lot like a ''VideoGame/DanceDanceRevolution'' stage. By the time you fight her, the best equipments you can have are the Ballet Shoes and the Old Tutu.
* Why are Toriel's pie flavors of choice butterscotch and cinnamon? Because the appearances of those ingredients are reminiscent of the body and shell, respectively, of a snail.
* Before the battle with Photoshop Flowey, he says that he has six SOULs, and he needs one more before he "becomes God". Considering that all the monster [=SOULs=] combined are the equivalent of one human SOUL, he technically ''does'' become "God" at the end of the True Pacifist path. The "Absolute God of Hyperdeath", in fact.
** This can suddenly dive into FridgeHorror when you think about it: what happens if Flowey/Asriel gets not only all those [=SOULs=], but also Frisk's? Furthermore, if Chara's SOUL is available to obtain, or if it ever existed in the first place, what if he also obtains Chara's SOUL on top of all of that? Think about it for a moment...
* Mettaton's song warns you about Asgore: "it'll suck / and then you'll die a lot". In any other context, this would just be lazy songwriting, but in this game dying a lot, and reloading in between, happens in-universe, especially in the fights against Flowey and Asriel that the Asgore fight leads into.
* Why is the best armor obtained by paying for shopkeep Temmie's college? Because Temmie's the AuthorAvatar of one of the game's main creators. You're [[BribingYourWayToVictory bribing one of the creators of the game]] [[EasyModeMockery to make it easier for you!]]
* Sans' boss fight. Why does he get tired? Because his attacks are telekinetic. Every time you fight him, lose, and load your save to try again, ''you'' get to start fresh. From Sans' perspective, it's always the single fight, which means he never gets a chance to rest his mind between fights. The ''only'' way to beat him is to tire him out.
** What are you talking about? Sans starts fresh when you restart, too.
* Given that Toriel is MyBelovedSmother and a MamaBear, it seems odd that Flowey, who is the reincarnation of her son Asriel, does not go to her for help, seeing her as either someone to save or murder when he has the ability to save and reload; given she's willing to die to see if you are strong enough to survive outside the Ruins, she would do everything in her power to keep a transformed Asriel safe. Then you get to the True Pacifist ending, where a crying Asriel begs Frisk not to tell his parents what he has become, because he has done terrible things as a flower and will horrify them when he reverts to that soulless form. On a subconscious level, Flowey is ashamed of being stuck in flower form, so much that he will not exploit his mother's kindness and love, even if having her as an ally would be better if for selfish reasons on his part. That form of pride lacks compassion, which means Flowey can maintain it without needing a soul or a conscience. Alternatively, which would overlap with FridgeHorror, is that if Flowey ''did'' seek Toriel's help and tell her who he was, he certainly wouldn't be satisfied with the results.
* Sans isn't fat. He's ''big boned''. I swear this game needs a section for Facepalmers next to the Headscratchers.
* Of course Alphys collects terrible anime, she gets it from a garbage dump so deep under the earth that only the worst of the worst crap is going to end up there.
** Are we going to find the lost copies of the ET Video Game down there too, perhaps?
* The tendency of the in-battle dialogue box to tell you what bosses and minibosses smell like (e.x. that Papyrus "smells like bones" and Snowdrake "smells like a wet pillow") seems a little random as far as {{Running Gag}}s go, but then again, ''Toby Fox'' ''is'', apparently, [[AuthorAvatar a dog]]...
* The dusty toys at Home. It's easy to get chills because, especially after a No Mercy run, you know quite well that dust equals death, but all the dust you encounter is the immediate result of monster-slaying (for instance, the Old Tutu is remarkably dusty and suggests that the human who wore it originally killed at least one monster). But then recall how monster funerals work: they scatter the ashes of dead loved ones over their favorite things. Those are ''Asriel's'' ashes. His parents gathered up the ashes from the golden flowers and scattered them on his toys, not realizing that his consciousness had already gone into the flower bed. Even worse: ''no one has touched them since it happened'', Asgore still has his children's room enshrined, showing that he's still deeply grieving them.
* Despite Sans's mercy appearing fake, his "dunking" could be considered a MercyKill, thus fulfilling ExactWords. Even if he let the player live and they don't kill anyone else, it's highly unlikely that the monsters will ever forgive them. No establishment would serve Frisk, leaving him to starve to death alone anyways. At this point, the player's only options are to complete the No Mercy run or to reset. Also let us consider what happens if Frisk gets past this point in a No Mercy run and how it taints all future timelines...
** Furthermore, Sans knows that Frisk is being controlled by an anomaly (the player). By killing Frisk, he's giving them a chance to be free from the anomaly's control.
* With 1 of each stat, Sans is listed as likely the weakest enemy in the game, but considering how powerful he is against the player in-game, this would sound like BlatantLies, right? However, the things that make Sans so powerful against the player probably wouldn't work as well against other monsters.
** His Gaster Blasters not only do draining damage, but are also implied to only do damage based on negative karma. Even the worst monsters are more along the lines of just aggressive or jerkish, and none of them can really be called evil. Not only that, but most have more than enough HP to survive against hits from the blasters even if they could be damaged.
** Sans is able to dodge all of your attacks, but why wouldn't he be able to when the main attack used by a player by that point is a straightforward slash? Many monsters have much more complex attacks that Sans would never have as easy of a time dodging, and with 1 HP it would only take a tap from even a weak attack to do him in. Sans really is the weakest monster, if he's only being compared to other monsters.
* The area music slows down when you're on a No Mercy run... because you're under the effect of [[https://en.wikipedia.org/wiki/Tachypsychia tachypsychia]], or the altered perception of time due to body chemicals produced from high-stress situations. You're in such a rush murdering everything that moves that time seems to slow down for you.
** As said in a Website/YouTube comment, this can also be symbolic: the weight of your sins is so heavy, ''it even slows down the OST.''
* The war between monsters and humans began because humans feared the monsters' superior magic, even though the monsters are still much, much weaker than humans regardless. After the Pacifist Ending, there's a whole new option for harmony between the races: If a monster and a human both die, the monster's dust can be used to infuse their consciousness into an inanimate object, which can then be injected with Determination and absorb the human's soul, which allows both creatures to remain alive after death as a half-human/half-monster automaton. It also means that there's hope for Flowey after all.
* A meta example. During the Website/GameFAQs BEST.GAME.EVER. poll, the last fight between ''Undertale'' and ''VideoGame/TheLegendOfZeldaOcarinaOfTime'' had a screenshot of Asgore amongst the six human [=SOULs=] as a representative image for ''Undertale''. Except...in the screenshot, Asgore has the light blue, orange, dark blue, purple, yellow, and ''red'' [=SOULs=] in his possession. In ''Undertale'' proper, the red [=SOUL=] belongs to Frisk and the green [=SOUL=] of kindness has been taken. It's a little confusing at first, until you remember the context of the image, and who from ''The Legend of Zelda'' is primarily green and has a kind spirit (and, like you when your SOUL is green, faces danger head-on and knows how to block attacks)...
* The final boss of the Pacifist path never requires you to use the FIGHT button. The final boss of the Genocide path never requires you to use the ACT command. And the final boss of the neutral path requires both of them to defeat.
* If you kill Papyrus on a Neutral Run, Sans calls you a "dirty brother killer". The Fallen Child ''is'' a dirty brother killer, even if you don't kill Papyrus. They are responsible for the death of their own adoptive brother — Asriel. Also, who is the last person you kill on a Genocide Run? Flowey. Asriel's reincarnation.
* Sans is really good at dodging. Of course he is. He knows all about the fact that other timelines exist, including the Pacifist run, and that's how ''you'' managed to survive.
** It's mentioned in passing that monsters use magic for everything (such as cooking). Sans has only 1 health point. Of course he has to be amazing at dodging, if any kind of accident could just insta-kill him.
* The Delta Rune is referred to by monsters as a symbol whose meaning has been forgotten — all they can remember is that an angel will save everyone, or it will kill everyone. Regardless of the outcome, the Underground would never be the same... and in some forms of scientific terminology, "delta" is used as an indicator of ''change''.
* Why can't you get the Temmie Armour in a Genocide run? Well, the population of Snowdin would at that point be either dead or evacuated, leaving the [[InsistentTerminology Librarby]] completely empty, which is the only place even remotely resembling the "colleg" that an aspiring and prospective Temmie could go to.
** Two other possibilities: Either even Temmies can recognize at this point that helping you is a bad idea (note that in the colleg's place is some premium Temmie Flakes that cost the same. An attempt to scam you, perhaps?), or anyone who's sticking with the Genocide route at this point wouldn't be that generous anyway — even if the option is still there in-universe, the PC isn't seeing or registering the option because they can't comprehend the idea of helping a monster.
* The true difference between a Neutral and True Pacifist run. In a Neutral run, even if you do everything right, there are still two encounters, Asgore and Flowey, where you ''have'' to Fight. However, upon doing so, Flowey's advice is to reload your last save, which is right before the fight with Asgore. That's the reason what occurs next is the ''True'' Pacifist run. By going back to that last save, those battles never happened. As far as the timeline and the people of the Underground are concerned, Frisk has ''never'' been violent.
* Probably the subtlest instance of [[BookEnds bookending]] in the whole game: the cutscene before the fight with Papyrus and Sans' judgement are similar in a subtle, but definitely not accidental way. In both cases, we enter long, mysterious and completely silent locations, with only shadows of our character visible (in Snowdin — due to the fog, in Judgement Hall — due to windows only lighting Frisk from sides opposite to the player). We go forth a little, and then Frisk suddenly stops. The camera moves forward a little, revealing one of the Skelebros blocking our way (either Papyrus appearing from the fog or Sans teleporting behind the pillar). Cue him giving us a speech about love and friendship and judging our actions up to that point. Also, in both cases, once the cutscene (and, in the case of Papyrus, fight) ends, the Skelebro leaves in the same way as they got there (Papyrus hides again in the fog, Sans teleports away).
** Don't forget Sans' scene with you immediately upon entering the ruins. It's even symmetrically a bookend, since the camera pans BACKWARDS to show he's there.
* The maximum possible LV you can have is 20, in theory for killing every single monster. You get it upon killing Sans, which only leaves Asgore and Flowey as the only ones left alive. Why would your LV be maxed out if there are still monsters around? Papyrus and Sans aren't from the underground. The shopkeeper says they've just asserted themselves here, one day, out of nowhere. They're supposed to be the extra 2, but you kill them before you get to Asgore and Flowey.
** Shopkeeper in Snowdin says they aren't from Snowdin — not that they aren't from Underground. Also, 20 is maximum possible LOVE — not LOVE you get for killing every living monster — just like in Pokémon, where lvl 100 is the highest you can get, but it doesn't mean you have to KO every living Pokémon to get there. On a Genocide Route, you kill every monster in locations you traverse — not in the entire Underground. It's explictly stated multiple times that many monsters just ran away from us, and in Hotland there is mass evacuation. And, if nothing else, there are several unique monsters that we can't kill during Genocide: Napstablook, Monster Kid, Alphys, and Amalgamates. Also, if I'm not mistaken, while sparing Glyde or Shyren ends the genocide, you don't actually have to encounter them (only unique enemy that has to be killed in a Genocide run is Snowdrake).
* Asriel's 'rainbow trail' in the fights against him is very prominent and most of his attacks feature rainbow colors. It's not really a rainbow though. It cycles through every color ''except red'', because Asriel doesn't have Frisk's red SOUL.
* A Monster with a human SOUL is described as being with not only a terrifying power, but also a very unsettling look. One of the main components of human [=SOULs=] is Determination, and we know very well [[BodyHorror what happens when a monster body is injected with Determination...]]
* In Victorian flower language, buttercup means humility and childishness, but also ingratitude and self-interest. Giving someone a bouquet of buttercups is a warning that our feeling towards them, while true, isn't completely devoid of desire for any profits. Now, why did Chara poison themself? Because they saw it as the only way to free the monsters — but also, more importantly, as the only way to get their revenge on humans. Also, if we go with the "Chara is evil" view, them using buttercups of all possible poisons to poison Asgore shows their lack of gratitude for everything they got from him and his family.
* Temmie reduces her price for Temmie Armor whenever you die, because she's ''[[AuthorAvatar one of the creators of the game]]'' (the other being the Annoying Dog), and thus aware of the fourth wall.
* So Undyne, instead of letting Papyrus become a full-on Royal Guard, invited him to hang out with her instead as sort of a requirement to become a Royal Guard later. This makes more sense, when one realizes that Papyrus truly becoming a Royal Guard would mean that he'd spend more time with the Snowdin Canine Unit. Papyrus doesn't really get along with dogs of any sort and the Canine Unit acts very dog-like most of the time. They'd try to be friendly to each other, of course, but in the end it would be pretty stressful and therefore bad for the Guard itself.
** Becomes FridgeLogic though if one considers that the Royal Guard is ''also'' stationed in Hotland. Papyrus as a skeleton should have no issue with the heat, the guards there aren't dogs, and Papyrus would definitely be motivated enough to move for a chance to be a guard. So her explanation that she simply thinks he is too much of a lovable goof to be a guard to begin with makes much more sense.
* Mad Dummy is a sort of [[EvilCounterpart meaner counterpart]] to Undyne. Undyne represents anger used productively, filling your good deeds with passion and keeping you determined. Mad Dummy's anger blinds them and distances them from others. Mad Dummy eventually becoming Undyne's training dummy is a metaphor for productive anger triumphing over destructive anger.
** Following up to this, Knight Knight is the armor-clad, [[DistaffCounterpart Distaff Counterpart]] to identifiable-as-male Mettaton's EX form. As opposed to him, she looks scary, like a burly man, and although she is polite, she wants the human child (and humans) gone. Mettaton has no problems being rude, but intends to save humans. They are also both connected to Shyren in some way.
** Even Sans and Papyrus work with this dichtomy. Both are skeletons, guard the ruin entrance, and — from different viewpoints — are the strongest monsters next to Toriel and Asgore. But Papyrus is motivated, powerful and eager to succeed while Sans is lazy, weak, and unattached. At the same time, Papyrus is the one that is very friendly, trusting, gullible, and peaceful while Sans is calculating, skeptical, smart, and — if necessary — merciless.
* Weakness to negative emotions aside, monsters are shown to be [[MadeOfIron pretty tough]] (Undyne throws herself down a ravine to save MK, catches them mid-flight, cushions their fall with her own body, and emerges with only some minor injuries; Papyrus jumps out of the window and doesn't show even that, and there is also a RunningGag of Undyne suplexing everything and everyone, and the fact that monsters use their normally lethal magic for such trivial things as making birthday cards). OF COURSE they are hard to kill — their bodies are made mostly of magic and are strongly implied to be much simpler than normal, "physical" beings. Their bodies are just simple, material forms with no viscera of any kind — there isn't much to damage, meaning that the only sure way to kill a monster is to either [[ChunkySalsaRule completely obliterate their body]] or [[AchillesHeel disrupt their magic — for example, with strong, negative emotions.]]
* It seems most monsters that fight you don't mean any harm — some seem to be playing, or it's just in their nature. (Of course there are exceptions, like the Royal Guard, but even they're very easy to talk down.) The fact that they haven't seen a human in awhile may contribute to why they're not being more careful... ''or'', when you keep in mind that what passes for "human history" in the Underground is comic books and cartoons, some monsters may be under the impression humans are much more resilient than they actually are.
** Actually, it's stated by many monsters in the PlayableEpilogue (most notably Bratty and Catty, but also several more) that they didn't even recognise Frisk as a human in the first place (and some, like Onionsan, ''still'' don't realise that they are one), and one of the books in Snowdin Librarby implies that monsters are much, ''[[NoSell much]]'' more resistant to magic than humans. Yes, the monsters we meet ''are'' playing around and they ''do'' think that the protagonist is more resilent than they are — it's just not because they are overestimating the resilence of humans, but because they think they're a fellow monster and something lethal to a human would be nothing to them.
** When doing the Genocide route, even though the player character is always at their very best regarding stats, they still take considerable damage from monsters. So it could even be assumed that, while the will to kill is the fatal flaw of monsters, magic is the fatal flaw of humans. Frisk/Chara are just naturally weak to it, so even a weak, harmless nudge with it does hurt the child a lot.
** Since monsters are damaged by KillingIntent, it makes sense that a monster launching magical attacks at another monster without any intent of causing harm will result in said attacks... well, not doing any harm. Humans don't work that way; [[AccidentalMurder accidentally killing]] a human is very, ''very'' possible even if no harm was intended, as the monsters of the Underground are likely to learn the hard way if the player can't handle the BulletHell.
* In combat against monsters, damage is determined less by inflicting physical damage and instead by the expression of killing intent. Part of what makes the player so powerful in the Genocide route is the raw, unrestrained ''bloodthirst'' from the player and Chara. Each boss is killed in one shot, with increasing amounts of damage — both due to the increasing violence of the player, as well as their increasing level. It isn't until Sans, though, that the damage marker is ''maxed out'' — because the player, [[ThatOneBoss after fighting Sans]], probably is more than a little angry, and that emotion feeds into murderous intent. This is topped when Chara kills Asgore without any player input, doing a thousand times more damage in a surprise attack. Then, the extent to which Chara [[OmnicidalManiac hates the world]] is revealed: they attack the ''game itself'' for ''infinite'' damage.
** The definition of determination is "resolution or firmness of purpose", but in ''Undertale'', it's literally ''de-termination'', as in ''negation of ending''. That's why it prevents Flowey from committing suicide, how Undyne becomes ''undying'', creates the Amalgamates, and grants the ability to SAVE and LOAD and RESET but not END, which is a "choice" forced upon the player by Chara: having de-termination as an ability means being able to prevent conclusion, including that of the timeline! It also puts Sans' question of whether your special power means you have a responsibility to do the right thing in a new light: it might not be within your power to stop every bad thing from happening, but you have the power not just to choose the ''best'' ending, but the power to prevent all the ''worse'' ones from occurring.
* Fridge Heartwarming: Muffet is suprisingly okay with Frisk being a human. Most other monsters (with exception of [[SeenItAll Sans]], [[CreatorCameo Temmie]] and [[TheLastOfTheseIsNotLikeTheOthers Tsunderplane]]) either don't recognize them as one, or are extremely worried and/or excited about meeting a human. Muffet, meanwhile, [[UnusuallyUninterestingSight doesn't seem to care at all about it]] and only attacks them because she is tricked into it by Mettaton ([[RonTheDeathEater NOT as a mugging attempt, contrary to what some people would say]]) and immediately backs off when she realizes she attacked an innocent person. She does mention taking their soul and breaking the Barrier, but she seems to see it as a nice bonus rather than a purpose in itself. But why? Doesn't she care about freedom? Of course — she doesn't! There are still many spiders trapped in the Ruins [[NoOneGetsLeftBehind and she's not going anywhere until she can save them]]. For what she is concerned, the Barrier might as well not be broken.
* The Pacifist Route is forever locked to you if you kill even a single monster because [[spoiler:Flowey/Asriel needs every single monster's SOUL to equal one human one and break the barrier]]. However, according to one of the signs describing monster history on the walls in Waterfall, [[spoiler:it would take ''nearly'' every monster's soul to equal a human one, not ''all'' of them]]. Why the difference? [[spoiler:Because ''Asriel'' no longer has his soul, meaning you ''do'' need all of them ''now'', but not at the time the signs went up.]]
** There's a second reason for it as well. To get the true pacifist ending, [[spoiler:you need access to the true lab, and to get there]] you need to befriend Alphys, which requires befriending Undyne. Undyne's friendship is completely conditional on whether or not you have ever gained EXP — one murder before the friendship sequence and it's [[PermanentlyMissableContent inaccessible until a reset]], and if you murder after the friendship sequence, she stops being your friend and generally acts betrayed, which would presumably cause you to lose favor with Alphys as well even if you've befriended her, locking you out of this ending. [[spoiler:And as others on this page have stated, the time needed to complete the true lab and bonds of friendship you have forged on your journey are both pivotal to Flowey's plan to gather all of the most powerful monsters in one place, which is necessary for him to become Asriel.]]
* When Alphys calls Mettaton's cooking show and suggests using a vegan substitute for a human soul, some players might notice a plothole with how the cake already has milk and eggs as ingredients. But since monster food is created with magic, the milk and eggs (and by extent, all monster food) would technically be vegan too!
* What does Muffet has in common with the Purple [=SOUL=]/Perseverance? Well, minus the obvious fact that she's trying to ''preserve'' the spiders in the Underground... Try to remember that whoever was the Purple Soul had a notebook. Now, if you have some lined paper, try to draw a heart on one of the lines.
* What colors does Sans' eye flash in the Genocide run? Yellow and light blue, the colors associated with justice and patience, respectively. Traits Sans shows ''plenty'' of; he not only stayed his hand until the end and gave you all the warnings and opportunity in the world to change your mind and back out of the Genocide run, but as a boss, between the [[SNKBoss well-deserved ass-kicking he'll give you]] for your murders and his willingness to [[SealedEvilInADuel stay trapped with you for eternity]] to keep you from destroying the timeline... yeah, Sans has justice and patience '''''in spades'''''.
* Undyne seems baffled as to how Sans keeps getting hired to run different sentry stations, but it makes perfect sense why Asgore would want Sans working for him. Sans can be incredibly capable when necessary, but he's too lazy to take his job hunting humans seriously otherwise. This attitude makes it take that much longer for another human to be captured and killed, which Asgore really wants to put off as long as possible.
* Why does Sans constantly teleport around and change his expression as he's attacking you? Because he's trying to distract ''you'', the Player, by making you look at him rather than his attacks.
* Some particularly skilled players pride themselves on killing Sans (as well as many other video game bosses) without taking any avoidable damage. However, due to his [[OneHitPointWonder sole use of dodging attacks]] to avoid dying, Sans [[SugarWiki/MomentOfAwesome "no-hits" many players numerous times in a row]].
* Why is there a RunningGag about the smell of different things in the underground? The sense of smell is the sense that is most linked to memories. If something is memorable, one of the things that you will take note of, at least subconsciously, is the smell of that thing. considering how memorable everything in the underground is, no wonder the smell would be noted quite often.
** Adding to that, you smell things when you breathe and most of the quotes about smell come from battles. When your adrenaline is spiking, more oxygen is in your bloodstream, meaning you need to breathe more. You are smelling more during a fight than outside of one.
[[/folder]]

[[folder:FridgeHorror]]
* [[https://twitter.com/UnderTale/status/367261618700161025 One post]] from Flowey on the Twitter page winds up CrossingTheLineTwice after you've played the game:
-->''[[KillEmAll Strive every day to increase your "LOVE."]] [[GenocideFromTheInside Remember, "LOVE" comes easiest from friends]] [[SelfMadeOrphan and]] [[SiblingMurder fam]][[OffingTheOffspring ily]]. [[SlasherSmile =)]]''
** This gets even worse after you discover Flowey's backstory in the Pacifist route; his death actually did occur because of the plan he hatched with The Fallen Child. Afterwards, they both found themselves involved in the deaths of multitudes, including, in Flowey's case, his own father. LOVE really ''does'' come easiest from friends and family.
* Your room in Toriel's house has lots of toys and shoes. Plus there's a chocolate bar in her fridge. Clearly these all belonged to kids that she rescued before. The same can be said of the equipment you find through the game, which are all used by their souls during the Omega Flowey battle, as mentioned above.
** One reason why a few players believed until the end that Toriel was actually AffablyEvil was because the boxes filled with shoes look a lot like LosingAShoeInTheStruggle; some Let's Players even mentioned it reminding them a lot of the [[http://remember.org/jacobs/shoeheap heaps of shoes that Nazis collected during the Holocaust]].
** Also worth noting is that in a Genocide run, once you reach Asgore's home and Chara is more or less dominant. Chara's first reaction upon seeing the fridge is to complain over the lack of chocolate.
* In the corner of your room, there's a child's drawing of a flower posted up on the wall. Easy to overlook at first, but after seeing the culmination of Flowey's BatmanGambit, it takes on an entirely sinister connotation.
* Toriel idly bats aside Flowey like a pesky bug with a single fireball in the beginning. And then you find out much, much later that Flowey is basically her bloodborn child reincarnated into an apathetic flower with no soul. [[AdultFear She unwittingly shot her own son and had no idea.]]
* Toriel asks you to fight here to "prove" that you can survive in the underground. But, despite how much damage you inflict on her, she never surrenders, never admits that you're strong enough. So, either she's trying to stop you at all costs even if it'll kill her... or [[SuicideByCop she actively wants you to kill her because she can't take it anymore]].
* We don't get ''many'' clues as to what the six humans that came before the protagonist and after the Fallen Child were like, but what we do implies that a couple of them were just as cruel as the player can be. Most prominently, the ballet shoes "make you feel dangerous" and the tutu is [[InferredHolocaust covered in dust...]]
* The whole deal with Sans' "dead where you stand" speech, though not in the way you might think. Frisk still has the power to Reset, and would therefore survive the attack. Sans would end up trapped in the same HopelessBossFight situation he enters in a Genocide route, except this time it would be his fault. And Frisk would have every reason to assume the worst of the rest of the Underground, likely leading to a Genocide run.
* If you die to Asgore, the Talk command will have you tell him that "he's killed you [x] times already." Which he fully acknowledges. Asgore is either very accepting of that possibility despite its seeming outlandishness, or he is ''very'' aware of the SAVE function. More so, [[GameOverMan his voice encourages you to not give up]] in the GameOver screen. He does not want to kill you this much. And he knows exactly how many times he had to kill a child around presumably eight years old.
** Alternatively, a more chilling idea for the GameOver speech he gives you: he's saying the Fallen Child's name, not Frisk's. It's a memory to when the Fallen was dying due to their self-poisoning, since the speech is semi-derived from one of the VHS tapes of their family, not Asgore himself trying to encourage you or Frisk to continue.
** Speaking of the Talk ACT, using it three times will cause Asgore to have a moment of recollection that halves his ATK and DEF, which can make you wonder; out of the seven humans that died in the underground, how many of them faced Asgore? And how many of them used their final words to beg Asgore to spare them, only for Asgore to force himself to deliver the killing blow?
*** Toriel's WhatTheHellHero speech during the Pacifist run strongly implies that no child ever made it to him. All he ever got to see were their souls being delivered to him. Frisk/Chara is the first child that ever made it to him alive, which adds another kind of FridgeHorror: he not only has to become someone who WouldHurtAChild, he also has to kill one that looks a lot like one he had once loved and lost. The fight against Frisk is the absolute nightmare of every adult that ever had to go through losing a child.
*** Toby Fox has now confirmed that they all made it to Asgore...and were all slaughtered by him.
* No Mercy Path:
** In the No Mercy path, Sans attempts to be [[ThatOneBoss the most frustrating possible challenge]] in the hopes that the player will give up and either reset or abandon the game. But he's actually [[BestBossEver such an intense and stylish opponent]] that, along with Undyne the Undying, he winds up drawing players into ruining everything for the sake of battling him.
** In conjunction with the above, Sans' 'special attack' consists of him just stalling, hoping you'll get bored and quit. This takes place after he throws everything but the kitchen sink at you in an attempt to frustrate you into giving up. If Sans had simply refused to use his turn from the start, rather than going all-out and trying it only when he was exhausted from the previous fight, he might have been able to stay awake much longer, turning his battle from an intense and stylish one into a struggle against boredom. How many Genocide runs might never have happened if it was known that the the Sans battle was just incredibly dull rather than [[NintendoHard the game's ultimate challenge]]? How many times has Sans caused his brother and friends to die by so terribly miscalculating, assuming that a frustrating battle would deter the player, when it's actually [[ChallengeSeeker the only reason]] many players did a Genocide run to begin with?
*** What happens if the player decides never to complete the Genocide run, but wants to fight Sans over and over? Sans learns that his ploy to stop the player from destroying all timelines [[GoneHorriblyRight worked far too well]].
** On top of this, Mettaton NEO's theme song, "Power of 'NEO'", is even a reference to this. It carries the same basic melody as "Battle Against A True Hero", the song that plays when you fight Undyne the Undying. However, it's just that melody, repeated ad-infinitum for 30 seconds, before looping. It's all style and no substance, just like the actual fight with Mettaton NEO.
** Near the end of the No Mercy path, the player finds the Real Knife in place of the Worn Dagger. Although it's likely Toby already had something like this in mind, this item began as a rumor about the demo version. To find out whether it was true or not, people went on a rampage through the Ruins. After it was disproved, people hoped it eventually would be implemented. And when the Fallen Child gets their hands on it, they're all left satisfied. It sure turned out to be a symbol of the bond between players and their murderous little avatar.
--->''About time.''
** Another thing to consider is that even though the Real Knife and The Locket maximize the player's stats, [[BraggingRightsReward there's no one left in the game to really use them on]], as Sans can't be hit normally and drains HP regardless of defense. Were those 99’s ''really'' worth all the bloodshed?
--->''Every time a number increases. That feeling... That's me.''
** In a No Mercy run, practically anything can be killed in one hit, so it's somewhat strange that it takes four hits to do Flowey in. Until you realize that maybe, just maybe, [[ColdBloodedTorture those multiple hits were intentional]]. After all, remember what he does right before you kill him: shift his face and voice to match Asriel's, the Fallen Child's adoptive brother.
*** Likely, considering that Asriel "ruined" their original plan by trying to fight back against Chara/The Fallen's soul. So this could be interpreted as, The Fallen was maybe considering letting Asriel/Flowey go until they remembered that, hence the pause before the button push, but then got so angry with Flowey that they chopped him up into bits.
*** More likely, since Frisk/Chara won't know about the circumstances of Flowey's creation in this timeline, is that the Fallen thinks that Flowey is using his death to mock them. Even if we assume that the Fallen is totally evil, they obviously had a connection to Asriel, or even just might view that death as "their" subject to mock – so there's ''no'' way they'd be pleased with Flowey attempting to profit off of Asriel's death, even just to save his own life.
** Why don't you get MercyInvincibility in the fight with Sans? Because you've had ''no'' mercy the entire time.
*** It's more likely that it's because it seems likely that [[https://www.reddit.com/r/Undertale/comments/9tej2w/delta_rune_revealed_why_sans_bleeds_tiny_dr/ Sans is a Darkener, and ''not'' a Monster]]. While Monsters are made up of ''Mercy'', compassion and love, Darkeners are made up of flesh and bone like humans. Sans doesn't give the option of MercyInvincibility not because you don't necssarily deserve it, but beause he's a Darkener and can willingly choose to give you that option ''because he isn't made up of Mercy''.
** And when you finally get to meet Asgore, you'll notice there's no Mercy button, and Asgore didn't even get to break the Mercy button on his own. Want to know why? Because you have ''removed'' the mercy.
** And by the time you meet Flowey, you automatically kill him, and you don't even have the interface when you fight him. Why? Because you were so desperate you're willing to go for InterfaceScrew just to kill someone, you stripped giving mercy out of your mind, and you automatically decided the ''only'' thing you do is to '''Fight'''. Furthermore, it's implied that the Fallen Child is in more control of your actions than you are.
* One of the creatures in The True Lab, "Lemon Bread," has the in-battle dialog "welcome to my special hell," and generally seems to be in a much worse state of mind than the other monsters in the area. Well, they're a fusion of the brother of Aaron, who's characterized by being very touchy-feely, and a Moldbygg and the sister of Shyren, both of whom care a lot about their personal boundaries (Moldbygg is spared with the "Don't Hug" action). Aaron's poor brother is in there somewhere, probably very scared and in need of the affection his kind craves, but will never get it again, while Shyren's sis and the Moldbygg are eternally fused to others, eliminating the chance they'll ever have personal space again. Special hell indeed.
* The Fallen Child:
** Imagine waking up in a bed of golden flowers, and the last thing you remember is being viciously attacked by a band of humans that ended up killing you and your adoptive brother, because of a plan you created with him. Suddenly, another human shows up and begins to kill each and every last monster they come across with no exceptions, even murdering your adoptive family.
** An interesting change occurs in the ending to a second No Mercy run, which may imply that the Fallen Child may not exactly be human, or may have something else pulling the strings...
** "Greetings, I'm [NAME]. Thank you. Your power awakened me from death. My "human soul". My "determination". They were not mine, but YOURS. At first, I was so confused. Our plan had failed, hadn't it? Why was I brought back to life? ... You. With your guidance. I realized the purpose of my reincarnation. Power. Together, we eradicated the enemy and became strong. HP. ATK. DEF. GOLD. EXP. LV. Every time a number increases, that feeling... That's me. "[NAME]". Now. Now, we have reached the absolute. There is nothing left for us here. Let us erase this pointless world, and move on to the next."
** And from the speech above, although the Fallen Child and the Player are technically separate entities, it's not hard to realize that they're NotSoDifferent given that pretty much every RPG has players grinding up on monsters (or even other people depending on story context) to become the strongest and complete the game. And to the child, everything is a game — even humanity and the monsters. They're all EXP to them, so they'll destroy the world and move on to the next to 'play in'. Just like you would any other video game.
** The entire twist that the child intentionally had themself killed by eating fresh, non-dried Buttercups, or Ranunculus. Poisonous to cattle, stock, and basically any normal living person, the symptoms of ingesting a buttercup are downright awful, to say the least. All to probably make their own demise as horrifying and traumatizing as possible to their adoptive family. If that isn't disturbing enough, Asriel and the Child 'accidentally' fed Asgore buttercups instead of cups of butter in a butterscotch pie, which makes you wonder if the Child basically tried assassinating him previously via illness just to disrupt everything.
** When you finally get to see them in-person, the Fallen Child is notably paler than Frisk despite the fact that in-story they seem almost identical in various ways. But on a No Mercy run, Frisk is noted to have white dust on their hands. As in, monster dust. It could very well be that the Fallen Child we see at the end is so pale because they're physically covered in the dust of all the monsters we murdered — and [[SlasherSmile still smiling like it's not even there.]]
** Also a bit of WMG. At the end of a Genocide run, the Fallen Child states that they were brought back by your determination. When were you at your most determined? During the fight with Asriel at the end of the True Pacifist run. This, of course, assumes that the player went for the True Pacifist run first. Judging by the Genocide route all on its own, the player's determination was there from the start and just kept growing with each kill.
** The PlayerCharacter avatar Frisk is clearly possessed by the Fallen Child throughout the entirety of the game. (Your first battle encounter, with Flowey, doesn't even have the name the player chose listed, so between encountering him and Toriel rescuing you, the Fallen Child gets stirred up.) If you walk the No Mercy route, the Fallen Child relearns their violent tendencies, which transfers into all the flavour text that they give you. However, if you go True Pacifist, their violent presence entirely vanishes and they're really not mentioned again. So what happened to Frisk's possession? Well, you stopped controlling Frisk and went on to play another game, didn't you?
** If a popular fan theory is indeed correct, YOU are actually the reason Chara/The Fallen Child becomes evil on the Genocide Route. Your mass murder convinces them that they were revived from the dead solely to kill, and they therefore help you towards that goal. The Fallen Child's own dialogue seems to support this.
--->'''Fallen Child:''' At first, I was so confused.\\
Our plan had failed, hadn't it?\\
Why was I brought back to life?\\
...\\
You.\\
With your guidance.\\
I realized the purpose of my reincarnation.\\
Power.
* Post-No Mercy:
** You learn that the Fallen Child's avatar is summoned by [[SpeakOfTheDevil saying their name]]. With this knowledge, now looking at Flowey's post-True Pacifist speech, it ends with: "See you later... [[OhCrap (name)]]." Yes, he's addressing YOU specifically, but the tragic irony is that [[NamesTheSame the Fallen's name is the same as what you input]]. For all the trouble Flowey/Asriel went through, they've unwittingly doomed themselves to becoming a hellbent sociopath again. Even in the GoldenEnding, Asriel ends up suffering...
** Even worse, the whole flow of the game was designed to be spoiled by the Fallen Child, and ends tragically. For now. Firstly, you do the normal neutral run. Then you want to see the true end, and Asriel calls the name of the Fallen. This ''is'' the first time you're called that out loud. Then the next logical step for the player is to check what happens on the genocidal route... Before you reset, Asriel begs you to not ruin the lives of your friends, that what you're doing is even more monstrous than what he was going to do. Little does he know, you're ''far'' worse. Furthermore, you murder the entire Underground. And if you refuse to destroy the whole world with the Fallen's help in the ending, it says that you never were in control. And as soon as you started thinking to kill all the monsters, you ''weren't,'' as the Fallen ''is'' the embodiment of the player's murderous intent. And when the typical player realises that this loop was happening? In the second pacifist route. After selling Frisk's SOUL to the Fallen. When the player knows what "Player Name" and being called that out loud really means. And this ending is spoiled by the Fallen's entity already. And the only way to prevent this loop is to call your character by their ''true'' name — Frisk. Which starts Hard mode. Which doesn't seem like it will be a reality, not from Toby Fox at least.
* Towards the end of the No Mercy run, the player finds the fabled "Real Knife" which maximizes their ATK, but why does this item show up so late in the game? Up to this point, most of the bosses have been easy to kill simply because the evil and hate in Frisk is so strong, and the fight against Asgore is no different, so having your attack power be so high is cool, but incredibly unnecessary. Then, the ending shows the Fallen Child, who has been in control of Frisk the entire time, and if turned down on helping them erase the world, they kill Frisk, and the screen fills up with a damage counter filled with '9's. The knife was never intended to be used by Frisk. The knife was for the Fallen Child the whole time.
* In a No Mercy run, Alphys evacuates everybody to "a place you'll never find them". What this means is more than likely the True Lab. With all the Amalgamations. She also mentions in the "whiff Metatton NEO" ending that saving everyone meant they all learned the truth about her, having to meet the Amalgamates first-hand, no doubt.
** More likely, they're all hanging out in part of the second floor of Hotland which is blocked off during a No Mercy run.
** Another thing about Alphys in No Mercy. Undyne tells you that she was watching you fight "in case anything went wrong." She tells you this ''as she's dying from overusing the same power that created the Amalgamates, melting the same way they do.'' Alphys ''saw'' all that. [[IronWoobie How she manages to stay sane enough to help everyone evacuate in the face of all that is impressive]], especially considering she becomes DrivenToSuicide in some of the less-drastic endings.
*** We actually ''don't know'' if she is able to deal with it. Only Undyne and Metatton mention her evacuating monsters, but when roaming Hotland, there are still plenty of monsters to kill. While it is possible that she did save some, there is also the possibility that seeing Undyne get killed pushed her over the edge, leading to Undyne thinking she will nonetheless save everyone and Metatton bluffing in the hopes that a few survive when the human thinks that no one else is there.
*** Considering Alphys takes over the Underground in a Genocide aborted at the last minute, she had to have survived long enough to at least start the evacuation. It's more likely that what we see is the player hunting down the last few monsters that hadn't managed to get away in time.
* So, the True Pacifist ending is mostly happy; however, there's a lingering issue of the fact of how sensitive to killing intent monsters are, if even a child can hate them really hard (albeit, the fallen's complete sociopathy affecting Frisk might mean normal humans are incapable of ''that'' degree of hate) and that makes them capable of being killed in a single blow by something that's not a weapon, that makes them horrifically vulnerable to the kind of criminals the human world has. Though Asgore seems at least somewhat aware of this when he mentions the human world can be a harsh place, still, everyone shown in the ending seems to be getting along fine.
** When asked, [[WordOfGod Toby Fox]] said that in the GoldenEnding, humans and monsters will peacefully get along from then on. Why is left open to debate.
* Consider the events of the Neutral ending that lead up to the fight against God/Omega Flowey. After killing Asgore, Flowey quits your game, and when you go back to it, the intro is altered to say that humans and monsters, rather than having a war, instead disappeared without a trace, before bugging out and bringing you to Flowey's save file. Now, God Flowey doesn't seem to have the power to actually kill everyone without the seventh human SOUL, as he says he'll only do that once he's finished with you... but his power over the save file gives him the power to affect ''history''. He eliminated the entire history of humans and monsters just so that there was no story that could get in the way of your battle — no story but ''his'', anyway. Of course, regaining control of the save from him allows you to put things back the way they were.
* Why would an approximate eight-year-old be on a mountain that's rumored to kill anyone who climbed it? Why are the ArcWords "But nobody came." so important? [[http://feralphoenix.tumblr.com/post/130534247404/wordbending-undertaled-room-89-what-i-like This secret room]] suggests that Frisk's parents might have just ''[[AbusiveParents left]]'' [[ParentalAbandonment them there]]...
** On that note, is it any coincidence that the Fallen is an unwanted child brought about by the Player's irresponsible actions and who wants to impose consequences on them? They [[DarkAndTroubledPast must've had]] [[FreudianExcuse some reason]] to hate humanity, after all.
** This is likely just a joke on behalf of ''Toby Fox,'' based on a [[https://twitter.com/fwugradiation/status/310482755341410304 bizarre experience he once had.]]
* Asriel comments that the Fallen Child was his only friend. Given what we know about that character, the chances that the Fallen ''specifically'' took steps to ensure that would be true by driving off anyone else that Asriel could call a friend are extremely high.
* During a No Mercy run, you may notice a few characters try to convince and persuade you to stop. A bit strange at first, until you realize they're not talking to Frisk OR the Fallen Child. They're talking to '''you''', the player, in the hopes of you abandoning the run and start over. You're the only one who can stop this horrible slaughter and you need to do it [[PointOfNoReturn BEFORE IT'S TOO LATE. (Unless, that is, you mess with the save files.)]]
* At the final battle of the Neutral route, Flowey has a LV of 9999. If both your levels work the same way — roughly the same amount of XP per run, and the population of monsters remains around the same — that means that Flowey killed everyone in the Underground approximately ''five hundred times'' before you face him.
** That or, if the corrupted opening you see before the fight begins is anything to go by, as an entry further up suggests, Flowey didn't just kill everyone in the Underground. He killed ''the monsters and humans of the past as well''. And he did it all ''just to fight you and make you suffer without interruption''.
** The alternative is that he's [[UnreliableNarrator lying/exaggerating.]] It's sort of a moot point, since no amount of LV will change how much damage a ''human'' takes.
** He's exaggerating, LOVE resets when the world does, and he's never been strong enough to kill Asgore or possibly even make it past Sans; he's just maxing out his stats because he's mad with power and wants everyone to know.
** One thing to keep in mind: Someone's LV doesn't increase their damage output for the same reason as in other {{Role Playing Game}}s. Your LV is your LOVE, meaning your Level Of [=ViolencE=]. Your ''willingness'' to inflict harm upon others. The reason monsters take so much damage from your attacks if you have a high LV is because their souls are made of magic, which makes them extremely vulnerable to acts fueled by hatred and violence. Putting that into perspective, consider that Flowey has a LV of 9999. By comparison, Chara/the Fallen Child can have, at the end of a true No Mercy run, a maximum LV of 20. The Fallen Child, who is willing to gleefully kill every monster in the underground, instigate a war between humans and monsters in the game's history, and ''wipes out the entire game world for no reason other than ForTheEvulz''... is close to 10000 points behind Flowey on the scale of how willing they are to hurt people.
* If the player goes full No Mercy in the demo, a special message is left for them on the ending screen saying "That was fun. Let's finish the job." in red text. At the time of release, most assumed it was a message left by Flowey. However, with the full release of the game, it's obvious that it's really from the fallen child/Chara, who speaks through Frisk in red text.
* The song that caps the end of a No Mercy run is ''Toby Fox''[='=]s BreakoutPopHit "Megalovania." Why is this the song for your fight against Sans even though there's an entire separate track for their battle theme? Because it's not their battle theme. It's ''The Fallen Child's.'' Consider the previous uses of Megalovania in ''VideoGame/TheHalloweenHack'' and ''WebComic/{{Homestuck}}'': the callous killing of another major character by a protagonist that had the option to make a less cruel choice but rejected it. Megalovania plays because the real fight here is Sans trying to save the world from an OmnicidalManiac: the Fallen Child, acting through you.
** To put a finer point on it, Megalovania isn't the theme for Your boss fight against Sans, it's the theme for Sans's boss fight against You.
** This is already proven when fighting Undyne. Before her fight, the player assumes they are still the main character. Undyne the Undying's theme is called "Battle Against A True Hero". By that point, you have officially become the VillainProtagonist and every boss fight is reversed, with you being the BigBad that a hero has to stop.
** This is further supported by Sans' ability to do a number of things normally restricted to the player, such as taking the first turn, dodging attacks, and making an off-guard kill against an enemy who didn't want to fight.
** In all actuality, it's possible the song is about ''fighting'' Megalomanics. Vania is a Hebrew baby name which means "God's gift." Sans is using the song to call himself God's gift to megalomanics I.E. '''you'''. Which in a way, he is. Sans breaks so many rules of the game, from removing MercyInvincibility to attacking you on the menu screen to sneak attacking you to changing the direction of gravity, that he seems impossible to defeat. So killing him would be the ultimate bragging right of any megalomanic.
* On the No Mercy route, Sans' "ISurrenderSuckers" instant kill seems like a serious dick move, both in and out of game. However, on further thought, it makes a lot of sense. Aside from said boss [[PayEvilUntoEvil doing everything he can to stop a genocidal murderer]], the fact that you would almost certainly kill him anyway if he surrendered for real, the thing that really makes it brilliant is... It's the exact thing you did to Papyrus. He immediately surrendered and opened his arms for a hug, and you coldly murdered him. Sans returned the favor for reasons of both pragmatism and giving you a KarmicDeath.
** Plus, the game gives the option to make every single monster (except Undyne and Metatton) spare you during the Genocide run, be it by acting or bringing their health down. Once the monster spares you, every attack will be an instant kill, with some (such as Toriel) even using their last breath to point out how evil and cruel it is. Since it is possible that some players [[VideoGameCrueltyPotential played that way]], having Sans use exactly that tactic is just him using your own tricks against you.
* If you call Undyne from the trash zone save point, she tells you about the first time she met Alphys: Alphys was standing on the edge of the waterfall, looking 'thoughtful', and was surprised when Undyne suddenly spoke to her. Undyne herself doesn't seem to realize it (or is hiding it for Frisk's sake), but it's pretty clear that Alphys was considering [[DrivenToSuicide jumping into the abyss below]].
** Undyne either knows or suspects. Watch her eyes during that conversation. She is very animated while talking about how she met Alphys, but she looks to the side once the 'thoughtful' portion is mentioned. She is likely trying to not give it away to Frisk.
* At the end of a No Mercy run, when Flowey is begging for his life, his voice changes to that of Asriel as he cries "Please don't kill me..." and looks at you with terror. You have rendered him so terrified of you he reverted to his childlike state, the same state when he was taking Chara back home when the humans mistook him for having killed Chara himself, and then proceeded to mortally attack him. You are now those humans in his eyes and are now seeing him beg for his life again in front of you... and as before, it doesn't work.
** Since why did you decide to kill Flowey when he was trying to help you?
-->"[[EvilIsPetty He made a]] KillSteal."
** It's entirely possible that Chara might have let Flowey live after all, save for one thing: in order to bypass the barrier, a human soul and a monster soul are necessary. Flowey ''destroyed Asgore's soul'', the last Boss Monster soul in the Underground, thus [[NiceJobFixingItVillain keeping Chara from bypassing the barrier]]! (Until, perhaps, a True Pacifist run...)
* At first, Papyrus' comment about having a low follower count online ("I'm only a dozen away from a double-digit follower count!") and Mettaton's comment about his low amount of viewers (it goes from 9 down to 8 and then to 7) seems like funny jabs at how popular they think they are vs how they actually are. This...doesn't really make sense. Papyrus is a well-loved member of the community in Snowdin, and Mettaton is supposed to be one of the biggest stars in the Underground. Then you remember the war between the humans and the monsters, and how so much of the land you travel is empty of life... perhaps the war took more monster lives than we thought.
** Though, the part about Papyrus isn't exactly true. Canonically Papyrus has very few friends, as shown by his secret desire to make them and the empty mailbox in front of his and Sans' house being implied to belong to him. Sans and Undyne are his only real friends before the player meets up with him.
* The random encounter mechanic itself becomes terrifying in a No Mercy run once you think about it. You know how the encounter rate slows exponentially the more monsters you kill? This means you have to move more to get into the next fight. Now imagine it from the monsters' point of view: You are actively ''chasing down'' the remaining monsters as they're fleeing in terror from a SerialKiller, and they only fight when there's nowhere else to run, in a desperate attempt to buy the others some time.
* Why does Omega Flowey have a screaming human's face on its monitor? That could've been one of the faces of the six human souls he absorbed. The face changes every time he changes attacks.
* Flowey lacked a SOUL, yet he had shown anger (and during No Mercy, he was shown to be perfectly capable of feeling fear). Monster souls are made of mercy, and compassion, and love. It was those feelings he can't feel anymore.
* Someone pointed out that King Asgore couldn't have possibly killed ''all'' of the Human [=SOULs=]. Most monsters aren't familiar with how a human should properly look, except Asgore and Toriel, who raised a human child, and Sans, who actively addresses the player as a human when he meets them. Now, notice how the equipment the player finds around the underground never even comes ''close'' to reaching Asgore's castle...
** In fact, Toriel actually called Asgore out on this during the Pacifist ending about how he is such a coward, waiting in New Home and hoping that no child makes it to him (or even falls down to begin with). Chances are that Frisk is the first child to ever have reached his throne room and thus force Asgore to raise his weapon against a human.
* There's a huge PlotHole with the neutral ending. How on earth did the protagonist cross the barrier if they lacked a monster SOUL? Flowey destroyed Asgore's SOUL, so there's no way that the protagonist kept one on them from any other monster they may have killed. Except... there's nothing to indicate the human left the underground at all. Sans calls them up and they don't pick up, so he just leaves a message. Also, he probably would not be able to reach the human's phone if they were in the overworld, leaving a heavy implication the human died trapped underground.
** However, if one takes the view that there is no continuity when the timeline is reset, the Neutral Ending is only a placeholder until the player inevitably resets...
** Alternatively, it could be that Frisk got transported to the Omega Flowey timeline and ends up trapped in that place where nothing but them and Flowey exist. They didn't die in the underground, they didn't make it through the barrier. [[AndIMustScream They are just stuck in a world where nothing exists but them.]]
*** This is supported by the final room of the Neutral run being a copy of the room at the beginning and end of the Ruins where you encounter Flowey. ''This isn't the room where the barrier is.''
*** Frisk seems to fuse with Chara, who has a bit of Asriel's soul in him. That's how he can leave the Undeground.
* Just before the final boss of the neutral run, Flowey says that with seven human souls, he could become God. At the end of the No Mercy run, Asgore dies. Asgore had six human souls. Chara then appears, presumably in the vicinity of Asgore's death. Chara then destroys the world. If you start the game again, the world is gone, and the only way to get it back is to give Chara your soul. [[OhCrap You're human. Chara already got six human souls from Asgore.]]
** Probably not, since it's stated that humans cannot absorb human souls.
*** It is probably quite similar to how Flowey was able to absorb all of the monster souls in the True Pacifist boss battle. He could only do this because he didn't have a SOUL. Both Asriel and Chara's souls were destroyed upon their death, so a revived Chara is just as soulless as Flowey and thus able to absorb human souls like he wasn't human.
*** But then again, as some of the posts above explain, there is a slight chance that the Fallen Child might actually not have been a real human.
*** The Fallen Child didn't die for good as a human. They died as [[DeathActivatedSuperpower an ascended Monster]]. They could likely absorb any soul.
*** There's also the possibility that enough murder intent makes you actually a monster as is implied in the Genocide route. Thus, the Child would also be able to absorb souls.
*** Also, selling your soul to Chara after a Genocide run wouldn't make much sense if they ''couldn't'' absorb souls.
* In the True Pacifist finale, Flowey comes out of nowhere and wraps all of Frisk's friends in a vine. Going along with a Fridge Brilliance further up the page, think about Sans and how low his HP is. If Flowey had sucker punched them all just a little harder, he could've killed Sans on the spot.
** When you think about it, Flowey probably made a point not to hit very hard. At this point, he wants to absorb their souls to add to the human souls he'd just taken. Most monsters' souls disappear the moment they die. So if he wants to absorb their souls, he needs to make sure he doesn't kill them too early.
* Given the timing of Toriel showing up in the pacifist ending, it's extremely likely that in the neutral ending, she arrives just too late to stop you from leaving. Given that she would be coming back to keep you from killing Asgore, it adds an air of tragedy to a mostly bittersweet ending, as she probably believes she failed to keep you from taking a life (Flowey finishes him off, or he does it himself, but in most endings they believe you directly finished him), and also lost Asgore, who, as much as she admits she dislikes, doesn't think he deserves to die for what he's done.
** It might have been Alphys that begged her to stop the fight after you reassure/befriend her.
* If you fight Toriel and kill her (either on purpose or by accident) and then reload/reset to spare her life, she'll remark that you look as if you've seen a ghost, and if you try and talk to her, you'll get "You thought about telling Toriel that you saw her die." and won't go through with it. For you, the player, it might not look like much, but from the character's perspective,
they either a) just killed someone who they were desperately trying to spare, and you have to look them in the eye, trying to find a way out while afraid you might kill her again, or b) you were so shaken by her death that you're faced with the perspective of having to kill her again if you don't find a way to spare her.
** Even worse in the latter case, as the player character could end up in a loop where they would keep killing her and going back to try and save her, but the only alternatives are getting killed or accepting that you killed Toriel, thus taking the first step towards turning into a monster.
** There's a third option, though less horrific. If you forget to save after fighting her (or your computer crashes before you have a chance to do so), you go through the Ruins exit... and walk into someone who you know IS SUPPOSED TO BE DEAD, and looks like a ghost.
* This has to do with the music 'But Nobody Came'. Like many things related to Flowey, specifically the Genocide/No Mercy route, it's a remix of his theme. However, unlike the other themes, which have a relatively high pitch and happy tone to it, this song is simply the first 'stanza' for the song. Repeating, over and over, unending and slowly reoccurring. It isn't just a creepy BGM to point out what you've caused — it's a hint to tell you that your actions in this run aren't redeemable. It's warning you about Chara's nature, in a way, by telling you, "You can't truly reset if you finish this run" because you'll be stuck in a loop with Chara owning your SOUL. [[https://www.youtube.com/watch?v=XKH1CxpqVco If you don't believe me, listen for yourself.]]
* If you try to play the game again after completing the No Mercy route. Chara has some choice words for you, wondering if you think you're above consequences. The thing is, ''they're more right than they know.'' No matter what you named them, Chara is not you. They're still a video game character, bound just like all the other [=NPCs=] within the rules of the game. You, on the other hand, [[HumansAreTheRealMonsters are a real person, and can delete your save files from the outside]], [[KarmaHoudini erasing all knowledge of the atrocities you committed]], as if you had never played,]] and not even Chara will know any better.
* It's been pointed out that Asgore and Flowey are the only characters who greet people with "howdy", hinting at their connection. There is one exception to that: when Papyrus calls the player after their date with Alphys, ''he'' starts the call with "howdy", suggesting that Flowey prompted the call and/or is feeding him lines to pave every step of the way to the trap he springs just before the True Pacifist boss fight.
** Flowey told Papyrus to tell Undyne to write the letter to Alphys, so this is pretty much a given.
*** The extent to which Flowey probably had Papyrus get involved in Alphys's date mini-plot makes the latter's appearance in goofy jogging attire toward the end of the actual date... well, a lot ''less'' goofy, in retrospect — it's not unlikely he was there in general because Flowey ''wanted'' him there, and had him see to/look into a way Undyne would leave him alone with Alphys so he could ask her to head back to the lab.
*** When he calls to inform the player about where to go, his BadLiar traits make the call quite suspicious. Especially when he begins sweating while repeating again and again that he only has [[BlatantLies "good feelings about this"]]. What did Flowey tell him that made him this extremely nervous to send Frisk to the Lab, considering he doesn't actually know what is inside?
* Everything about W.D. Gaster.
** His life has pretty much ended, and he's aware that the world just goes on without him as if he'd never been in it.
** The simple notion that there's something in the world of ''Undertale'' that can scatter you all over reality, erasing nearly every trace of your existence.
** His (unused) battle data. Aside from all being variations of the NumberOfTheBeast, Gaster's stats are '''''monstrous''''': 666,666 HP, 6,666 ATK, and 6,666 DEF. He would simply eclipse every enemy in the Underground ''combined'' if he were still around. Keep in mind that Photoshop Flowey has only 6000 HP.
*** Those numbers in particular: Remember that in this game, monsters aren't inherently evil, and most of them wouldn't hurt a fly if they felt they had a choice. That Gaster has the Number of the Beast for his stats is less likely to be a statement of being evil, and more of one that he's a ''transgressor''. To go along with his being DummiedOut, it suggests that he tried to break his programming, and was ''punished'' for it.
*** Interesting story, the first publicly available home computer, the Apple I, sold for $666.66 when it was first released. The developer, Steve Wozniak, had no idea about the number's connotations; he just liked repeating digits. Perhaps the use of these numbers (especially in regard to a scientist [[DummiedOut who can only be found by examining the game's code]], and was most likely well-acquainted with [[SatanicArchetype Asgore]]) was meant as a ShoutOut to this piece of computing history, while further playing on the game's Satanic FauxSymbolism.
*** There is also the implication in the lab that he also experimented on live creatures. While he didn't fight them in the meaning of the word, he might have caused a lot of death, thus raising his LVL and LOVE.
* If you do decide to permanently quit the game from being unable to beat Sans, then it results in what may be the ultimate PyrrhicVictory. Sans spends his boss fight trying to convince you to give up and quit. If you do, then he's also ensured that the timeline won't reset. So all the monsters you killed will ''stay dead''. Imagine Sans waiting there in the judgement hall for lord knows how long before he realizes that he's won, [[{{Tearjerker}} but he's also ensured that he'll never see his friends and family again.]]
** On the other hand, there's nothing stopping ''Flowey'' from resetting the game after this... If he can hijack the player's ability to SAVE during the Neutral boss fight, then, if the player leaves the game altogether, Flowey could easily get his ability to Save/Reload back. This looks like a [[HopeSpot good thing]] at first... Until you realize that this is still [[{{Sociopath}} Flowey]] we're talking about, and he's willing to do No Mercy runs himself. Regardless of what happens, Sans is either stuck with all his friends dead, ''[[MortonsFork or]]'' he's still going to be trapped in the GroundhogDayLoop.
* Flowey nearly kills you at the beginning of the game. Yeah, yeah, bad enough, but then, realize this means he nearly got his hands (leaves? roots?) on your SOUL. Recall that a monster with a human soul is insanely powerful, and this ''particular'' monster already has some experience with wielding that kind of power. There's no reason he couldn't have taken your SOUL, overpowered Asgore, and become his TrueFinalBoss form without any humans conveniently nearby to oppose him. In other words, it's very, very lucky Toriel intervened when she did.
** Except, if you pay [[https://youtu.be/O6RNVHQOjJ8?t=1m20s close attention]], you'll see that Flowey's "deadly" attack actually heals the player, and this is before Toriel shows up. This seems to indicate that the player character was not in any real, mortal danger — and this is ignoring the fact that even if the player did die, they would just get reset. Where they would be reset to is quite a good question, however, as at this point they haven't been to any Save Points yet. Maybe it just resets to the flower patch the game starts on, or maybe it resets to somewhere outside the Barrier, before the player character fell down. There's no definite answer here, but Flowey was almost certainly not in the position to take their soul and wreak havoc on the Underground.
** Just before that, though, Flowey asks "why would ANYBODY pass up an opportunity like this?", which would imply this to be his plan, as of that moment. Furthermore, he'd be familiar with the mechanics of determination, since he's used it quite a bit before the player's arrival... if he thinks that plan would work, it's likely he's right. After all, a defenseless human child who gets unavoidably murdered by the first, most innocent-looking thing in the underground might end up surrendering not too long after their arrival in the underground. Note that fighting isn't even an option here, and Flowey's on the one path out of the first part of the Ruins. There's literally no way the player can avoid him, and removing him from their path isn't an option, either. Even if the player resets back to the flower patch, they would still inevitably encounter Flowey and be hit with another barrage of "friendliness pellets". Toriel's intervention is pretty much the only thing that prevents [[BreakTheCutie the player character's repeated death]] [[DespairEventHorizon and eventual loss of determination.]] As for the healing... given Toriel's motherly personality, it's possible she has healing magic in her repertoire, and of course her first priority would be saving the child's life and preventing the fatal attack from landing (at the very least, it makes more sense than an attack Flowey meant to be fatal restoring the health bar to full). In a way, the ability to invoke SaveScumming in-universe just makes Flowey's NearVillainVictory that much worse, since Frisk's [[MortonsFork options]] are to either let him obtain the soul or be stuck in a GroundhogDayLoop.
* Sans knows SOMEONE, or SOMETHING, has been meddling with the timeline extensively, and for quite some time, and it is never confirmed one way or another that he knew that Flowey and not the PLAYER was the one doing it before Frisk fell into the Underground, and that one of the possible causes for Dr. Gaster's disappearance/splintering was Flowey's meddling with the timeline.....
* Flowey gets a FridgeHorror in-universe! At the end of the Genocide run, he cheerfully delights in how perfect his relationship with Chara will be, because of how well they understand each other as complete psychopaths with incredible power, until he mentions that they'll be so perfect together that they each wouldn't hesitate to kill the other if he should get in their way... and then he becomes ''terrified''. At first it seems obvious that Flowey realizes that Chara will completely outmatch him once the souls are put into play, but in the True Pacifist run, Asriel confesses that when he absorbed Chara's soul, ''Chara'' was in control and brought their own corpse to the surface in order to provoke the humans, but Asriel resisted in order to spare them and return home. Flowey remembered that he had already sabotaged Chara's plans ages ago, and Chara would absolutely still hold a grudge over it because if Asriel had done as planned, '''none of the events of ''Undertale'' would have ever happened and Chara would already have wiped humanity out'''. That's why he freaks out and why Chara gets the creepy look on their face: Chara never ''forgot''.
* Why does Sans become delusional when you kill him? Because he is aware of the time resets and has subtle memory of them as well. He knows time might reset and he'll be back with his brother and in Grillby's soon, and he is also hitting the DespairEventHorizon as he dies while his burdens and self-confessed inevitable failure come to a head.
** {{VideoGame/Deltarune}} [[https://www.reddit.com/r/Undertale/comments/9tej2w/delta_rune_revealed_why_sans_bleeds_tiny_dr/ implies]] that he actually ''did'' go to Grillby's in the end, so it might not be as bad as we think.
* Why is Chara able to absorb your soul after the world ends? Because they just murdered you. You still don't have a choice. They just want to play with the last human they will ever speak to before killing them.
* Let's take a moment to acknowledge that, for possibly longer than the Earth has been around, a small child has been caught in a time loop and forced to take the form of plant-genitalia. He has likely learned about this in one of the loops.
* When Sans unleashes his special attack (which turns out to be prolonging his turn to get you to quit), the only way to beat him is to drag the box you're in over to the 'FIGHT' option. The only hint you're given to do this? Any time you get too close to the lower left-hand corner, Sans' eye flashes blue, and you are thrown back to the center. His precaution is ultimately what causes his death.
* At the end of Genocide run, when you fight Asgore, the Mercy button is gone. In killing Sans, you have finally collected enough EXP to reach the highest LOVE. You have accomplished the ultimate goal of the Genocide route. You have distanced yourself completely. It's over. There's no point in a Mercy button anymore. You don't have any mercy, and you never will again.
* People's biggest complaint about the game seems to be that you can't save Asriel. By the look of Flowey/Asriel's save file in the neutral run, his 9999 LV means he's completed the No Mercy run around five hundred times. And as the player can find out, there's no coming back from a No Mercy run.
** Of course, that's assuming Flowey's LV was carried over from the resets.
** Seems like Toby had one final {{Deconstruction}} for us — the deconstruction of the NewGamePlus. The game itself gives you a taste of it with the ability to reset, but presumably, with the whole idea of the resets being 100% completion and seeing how the characters react, you don't keep your LOVE — because that would ruin the whole point of 100% completion, how can you get it when everyone is already dead? Flowey, on the other hand, doesn't want to experience everything the story has to offer — he wants to become a God, and he is shown to be able to hack the game. So he goes as far as he can in the No Mercy run, saves his LOVE, resets, and does it all over again. No wonder you can't Mercy him.
* What exactly ''is'' Tem Armor made of? Some players believe it's ''made out of temmies''. Some take it a step further and believe it's made out of ''living'' temmies. Let that sink in.
** Considering Tem Flakes are apparently shredded construction paper (and thus not actual Temmies), this seems unlikely. Plus, the player character is allergic to Tems, so this would mean that equipping the Tem Armor would hurt them. Though the fact that it's still not stated exactly where the Tem Armor comes from could still be some slight FridgeHorror.
** Although none of these theories would quite make sense since, y'know, monsters turn into dust when killed... They're more likely to be made out of cardboard which is another popular [[{{Fanon}} fan interperation]], if anything.
* Just think about everything Frisk goes through in this game, from being basically kidnapped by Toriel and being told they can't leave [She had good intentions, but still] to being relentlessly hunted by the greatest warrior in the underground to being trapped in a laboratory with horrific creatures created from accidental morphing melted monsters together to potentially being possessed by a sociopathic murderer...And then keep in mind that they're JUST A CHILD.
** Adding to the above, the same thing happened to the previous five humans who fell after the Fallen did. Heck, you can find the Toy Knife in the Ruins, where Toriel is supposed to protect you. Frisk just happens to be the one that has a chance at survival because they have one trump card: you the player and the ability to reset. And if you decide not to give Frisk that chance by going for a genocide...
* In a True Pacifist Run, Asgore waits for you when you decide to backtrack, help Alphys and Undyne and explore the True Lab, without moving away from the barrier at all. Is he that much of a DeathSeeker or does he feel that he can only commit to the deed by not even taking a tea break?
* In a Genocide run, you can keep taking pieces of the Snowman until he's reduced to a pile of snow but he never becomes ash. Not even after you eat his remains.
* The dialogue on the game over screen indicates that Chara is still motivated by Asgore's words and, when you reach Asgore in a Genocide run, Chara/Frisk doesn't kill Asgore. Flowey does in an attempt to get on Chara's good side. Then Chara starts killing Flowey, but Flowey changes his face to its original form to guilt trip Chara, which works until the player pushes the button to give Chara one last push. Even then, it takes a few hits, as if Chara still doesn't want to kill him. If Flowey hadn't killed Asgore, maybe it all would have stopped there.
** Which would be FridgeHorror though, after all not only did Chara kill Toriel just fine, they also had tried to kill Asgore by poisoning him way back.
** Also, the player only hits the button once, while Chara cleaves up Flowey multiple times. It's possible Flowey could've lived if he hadn't killed Asgore, but it's also likely that whatever remaining affection Chara may have had for Asriel was lost when he [[KillSteal killed Asgore for them]]. Not to mention Flowey's [[ExplainExplainOhCrap own speech]] on how being soulless means that Chara would likely kill him if he got in the way, and the real fridge horror here is that Chara was so far gone by then that they were willing to kill their adoptive brother. ''Brutally''.
* The list Chara gives at the end of a No Mercy run includes not only LOVE and EXP, but also GOLD, ATK, and DEF as well. Why is this FridgeHorror? Because even on a True Pacifist run, the player probably does grind for money in Temmie Village at least to get the Temmie Armor, and if not, they still try to make use of their gold and pick up the equipment left behind if not for anything else, for defense purposes. This is another proof that Chara has some effect in all runs, not just No Mercy, and they are the narrator.
** Doubly appropriate if you let yourself get killed a couple times to make the Temmie Armor cheaper. [[ThanatosGambit Committing suicide for a massive power boost]] [[NotSoDifferent was Chara's plan, too.]]
* Everyone seems to warn you about not going further with the Genocide route. Sans is the last person to do this, after telling you about how the he is aware someone is messing with the timelines over and over but it comes off as more of a threat after it's obvious he can't win. It is indeed too late to reset after this point. All this time you have had control, resetting after dying and doing as you wish. Sans was giving you your last chance to do a full reset and maybe make a more merciful run, but no. You pressed the issue and ended up in Chara's hands. They are resetting the world now and you can only reset because they allow it. Every playthrough after a full genocide is tainted by your actions and ends badly even if it's a full Pacifist route. Each one is reset only to end badly. Your own actions have corrupted Chara and you have damned yourself to the same fate that each and everyone else is in. A world of resets and you are more aware of this than everything else, even Flowey.
* After the Genocide run, whenever you complete the Pacifist run you get the worst possible ending, with Chara taking Frisk's body over and presumably murdering everyone. Normally, if you re-launch the game after a Pacifist run, Flowey pops up and begs you not to reset the game and take away everyone's GoldenEnding. I don't know if he does the same without a soul, but if he does, then he's pretty unaware of the bad ending, which is understandable, but terrible nonetheless; However, if he doesn't, then he clearly knows what happened and doesn't even bother talking to you.
* Imagine you're playing ''Undertale'' after a Genocide run. You now have 3 choices: Going Geno again, which just resets you to Status Quo, Going Pacifist, which will unleash Chara on the world, or going Neutral. No matter how you look at it, even the worst neutral non-genocide run is now a preferable alternative to the Pacifist Run — the one thing that's supposed to save everyone.
* In Alphys's lab, the player can find a bundle of unread letters from various monsters. Once you find out what's in the True Lab, you realise just why Alphys didn't want to read those letters... they're pleas from various monsters to know what happened to their loved ones, who became fused into Amalgamates.
** It makes sense when you read the log in the True Lab saying how everybody was apparently mad at Alphys. Those aren't just requests to know what happened; Alphys had said she was going to tell everyone that their relatives were okay. Some of those are probably angry letters demanding that Alphys stop keeping their family members hidden away from them.
* If you stop and consider the state of the previous six souls. They were killed and their souls harvested to [[PoweredByAForsakenChild give someone the powers of a god]] with the openly expressed intent of destroying everyone they had ever known and loved. We don't know what [[AndIMustScream level of awareness they had in their little glass prisons or how long they had been stuck there]]. And on top of everything else, it was clearly stated that they were experimented on and their determination taken from them and used by Alphys to create the Amalgamates when it had previously been explained that it was determination that let a human soul continue to exist after death. How are these souls still around or even sane at this point?
** If the faces on Omega Flowey's screens ''are'' the children, then the answer is: they aren't sane at all, anymore.
** They have to have at least ''some'' awareness left, since Frisk is able to call out to them, and they can rebel against Flowey, which also means they probably have at least a little sanity left. Though they're still stuck in an AndIMustScream situation until then, so it's not ''much'' better.
** Considering that Chara possibly possessed Frisk the entire time and the fact he died as both human and monster, perhaps Asriel's part of the soul allowed Frisk to escape.
* What happens when you think about a joke for too long: That Temmie that's allergic to itself?[[note]]OK, it says allergic to Temmies, but if you're allergic to your own species the point still stands.[[/note]] That's actually a thing — they're called Autoimmune Disorders. We can only hope that that Temmie's skin is the only affected area....
* So. Say Asgore managed to collect all human [=SOULs=] and break the barrier. The intro states that the first human fell in the year 201X. Frisk fell much later. So if Asgore wanted to start a war again... The humans are most likely gonna wipe them out, due to technological superiority.
* Several of the Neutral endings themselves are massive cans of fridge horror, if you think about them. For starters, in the timeline where Papyrus becomes king, all of the human souls, similar to every other timeline, vanish. The monsters fall into depression, and Papyrus tries to keep them happy. It's likely that whenever the next human falls down, Papyrus is going to end up in the same scenario as Asgore was, being forced to take the human [=SOULs=]. Sans is busy running things for Papyrus, and being busier, so Papyrus is going to have no shoulders to cry on.
** Mettaton's endings speak for themselves, considering his [[TheCaligula methods of ruling]]. And, if he gets any human souls, he could just ditch the monsters, going to the surface to be an entertainer. This does mean, however, that Papyrus or Sans might be put in charge, but, well, see the above.
*** Alternately, he does seem to regret some of the things he's done, considering his comments on Alphys in his endings. It's fully possible that Mettaton ''would'' abandon the Underground in a heartbeat if he got any human souls, partly due to his GloryHound nature and partly out of a misguided attempt to be TheAtoner (giving rule to someone else). And if Papyrus is still alive... well, see his ending, but worse, since he'd inherit all of Mettaton's problems.
** Queen Undyne, or Empress Undyne, declares war on humanity. And unlike Asgore, she's fully determined to see it through, minus the fact that monsters are weak to killing intent. If not for Frisk's ability to reset, she'd likely gain the seven souls, or, Flowey, still being alive, might kill her and become ''a fully powered Asriel, with no humans around to stop him, and allowing him to toy around with the surface.'' And the humans on the surface would have absolutely no idea what was coming, whether it be an army led by a HYPER-GOD Undyne, or The Absolute God of Hyper Death, who, unlike last time, is clearly not going to hold back.
*** The worst part about a full-power Asriel getting to the surface is that yes, it'll probably end in tons of humans being slaughtered... but only until the aforementioned character realizes what he's done. It takes him a little while of having extreme emotions before he realizes things like ''remorse'' and ''sadness'' and ''grief'' are part of him again, but it only comes back as fast as it does because he's screaming at "Chara", the person he loved and grieved for until he literally died. That realization is going to take a lot longer to set in if he's murdering strangers, and for all his other powers, he might not actually have access to the Reset Button aspects of Determination anymore. If he realizes he's a murderer who doesn't get do-overs, that will get ugly very, very quickly.
** Alphys, if she ends up queen, due to a botched Genocide run, is likely going to commit suicide, considering how she's done so for much less in other timelines.
*** What makes this horrifying is that the monsters would have a HopeSpot, since they managed to survive the Genocidal player character, only to have their queen kill herself, leaving them with nothing. It'd basically be an ''[[FromBadToWorse even more]]'' ''[[TearJerker depressing]]'' verison of the anarchy ending. One can only hope that Alphys manages to hang onto her [[GrewASpine newfound confidence]], at least long enough to pick someone else to rule in her place.
** Toriel's going to have to deal with the fact that you killed her ex-husband who, though he was not exactly good in her book, did not deserve to die, and she was too late to stop you. Or be exiled to the Ruins, if you killed more than just Asgore.
** And finally, Sans is going to be waiting for the next reset, no matter how good the neutral ending is. Even if you befriend everyone, and Alphys is working on a separate way to get the monsters out, Sans knows it won't last.
* So. The True Pacifist ending. The monsters have reached the surface, and now live together with the humans. The humans welcome the newcomers with open arms, and there are no significant [[FantasticRacism hard feelings on either side]] — the two races live in peace. But not all humans are nice. Some humans are very, very cruel. So cruel that [[{{Sadist}} their main idea of "entertainment" is tormenting or flat-out torturing others]]. These people are usually kept in check by law enforcement, who uncover their transgressions and use the evidence they find to track them down. However, if somebody were to murder a monster, ''there's next-to '''no''' evidence of the crime.'' Unlike human bodies, monster bodies instantly crumble into dust upon death, rendering an autopsy impossible, and monsters don't bleed, either, meaning that pretty much the only thing at the crime scene is a pile of dust that may or may not be indistinguishable from any other[[note]]hey, the game never mentions if monster-dust is any different from "normal" dust[[/note]], assuming that the killer doesn't just blow it away or suck it into a vacuum cleaner. Any {{serial killer}} who realizes [[http://internetwanderer.tumblr.com/post/149430333796/so-i-just-had-a-bout-of-fridge-logic-regarding just how easy it is to get away with murdering monsters]] '''is going to have a fucking field day''', and human law enforcement won't even be capable of doing a damn thing about it. No wonder the Soulless Pacifist ending is so ominous...
** For that matter, the reverse scenario could be even worse. Humans slaying monsters would be terrible, but at least a human murderer wouldn't get a massive power boost from it. If a monster becomes obsessed with a certain goal, is a natural sadist, gets a lust for power, or simply decides that co-existence is overrated, there is very little to prevent them from becoming a god-like being. They would simply need to ambush and kill a single human, and that human's soul would [[BewareTheSuperman turn them into a killing machine which would become ever more powerful with every victim it consumes, and will become potent enough to wipe out humanity after less than a dozen kills]]. It's also implied that ANY monster can absorb a human's soul, and since monsters are innately magic, it's impossible to disarm them. And now there are thousands (at least) of them on the surface, each one a potential PersonOfMassDestruction. Maybe the ancient humans had the right idea in sealing the monsters away...
** At a glance, this almost looks like a plot-destroying plot hole that turns the Pacifist ending into a severe EsotericHappyEnding, were it not for one thing: we do see in the game that souls remain self-aware after death, and are given partial control over the body they possess even after absorption. The scenario you describe nearly happened when Asriel went to the surface, but didn't because of Asriel FightingFromTheInside. Perhaps a homicidal monster could successfully wrestle into submission the soul of a single human, but after two or three they'd be outnumbered, and the odds of them making it to seven are virtually impossible. In addition, we know from the final battle of the Pacifist run that emotions are also shared when a body possesses multiple souls, which could very easily drive said monster into MyGodWhatHaveIDone and compel them to fix their mistake. The only possible way around this that I can think of would be if a monster were to make an agreement with seven equally homicidal humans (like, say, a terrorist organization) and have all seven of them commit suicide and be absorbed by the monster... looks like laws regarding human/monster relations are going to have to be written very, very carefully.
*** Another question one must ask is "How much determination can a monster's body handle?" according to Alphys' studies, not a lot. A mere extraction was enough for their corpses to melt away forming the amalgamates, which is likely to happen to the hypothetical monster serial killer. Not counting Asriel, who never had the will to fight in the first place, the only monster we see with determination matching the scenario of a human harvester is Undyne. Her normal form melted away the instant she took a fatal blow while her Undying form had almost as much determination as a human. Undyne said that her body was about to break anytime and that too melted once it was destabilized enough. Even Asgore's plan fails to account for this problem.
*** You have to consider that Alphys was injecting the Determination into the monster's ''bodies'', whereas if a monster absorbed those human souls, they might just fuse with the monster's ''soul'', so their body might never have to cope with the extra Determination from their souls. Supporting this is what happened with Asriel — will to fight doesn't matter, or at least it didn't there, he still had the Determination of six human souls inside of him and he was perfectly fine throughout the battle.
*** However, this is seemingly contradicted by the Photoshop Flowey fight, where the souls start rebelling after he tries to abuse save states long enough. This would imply that under certain circumstances, there can be "too many" souls in a body, and it would likely come down to how long a battle with them would last that determines how long they'd be able to last.
* It might not seem so at first, but recall the moment you give Temmie money to go to colleg. She leaves her face behind while the rest of her body heads off and returns shortly thereafter, having learned something new. While this is PlayedForLaughs on your end, just imagine this from the perspective of whoever she goes to visit. You'd be minding your own business when suddenly some faceless monster jumps out at you with a nightmarish screech (for example, hOi!!!) coming from god knows where. You'd throw whatever the nearest object was at it, [[FridgeBrilliance and if it happened to be a vendor's licence for a suit of armour...]]
** Temmie, with being a monster, probably didn't exactly scare whoever was at "colleg". What must be horrifying, though, is this: a child has finally gathered loads of money (or died a dozen times for price reduction), gives it to Temmie...and then is stuck for who knows how long with just their face staring while the body gets up and leaves.
* In the events leading to the True Pacifist ending, Toriel berates Asgore's inaction, pointing out that he could have used a single SOUL to cross the Barrier and get six more, rather than waiting for children to fall into the Underground. In the context of that timeline, yes, that seems plausible. However, you, the player, just beat Omega Flowey in order to get to that timeline, and you know what it was that broke his power in the end. The abused [=SOULs=] rebelled against him. If Asgore had tried to use a SOUL, who's to say the same thing wouldn't have happened to him?
** We know from Asriel-Chara that they dueled for control, with one only barely overriding the other. We also know from Omega Flowey that one monster and six human souls can't really harmonize, but then again, Flowey is a soulless determined flower, not an ''actual'' monster. Asgore as a boss monster ''might'' be able to control the human souls — partly. Best case, they somehow work together, worst case, [[DrivenToMadness he ends up like Lemon Bread]].
* More Fridge TearJerker, but one Youtube commenter pointed out something about how Papyrus has no attacks on a Genocide run.
-->Funny thing about this-\\
\\
People say Papyrus doesn't attack you in the genocide route. But that's not true. He does have an attack-one you won't see until the sans fight much later.\\
\\
Papyrus' death is depressing. Extremely depressing-enough for some people to quit the game.\\
\\
But his death-it makes you sad. \\
\\
A euphemism for sad is blue.\\
\\
When you kill papyrus, you become blue.\\
\\
[[IronicEcho You're blue now.\\
\\
That's his attack.]]
* Alphys kills herself in No Mercy
** It's made pretty clear that if you defeat Undyne and get to Hotland, Alphys is supposed to be the one to evacuate everyone to safety and notify Asgore. She's supposed to be the alarm system. But the alarm never goes off. Alphys told Mettaton she was going to go evacuate everyone to safety, but when you actually explore the rest of Hotland and the Core, everyone is still there. And when you get to Asgore, you catch him completely by surprise. He doesn't even know what's been going on. What gives? Seems like a plot hole. But if you consider all the hints dropped in Neutral and Pacifist, [[DrivenToSuicide maybe it's not.]]
*** ...Except that several monsters (namely Muffet, and later Bratty and Catty) mention that Alphys ''did'' start evacuation — she just wasn't able to take eveyone to safety in time (by the way, we only kill around 200 monsters on Genocide — and yet Mettaton's Pacifist boss fight strongly implies that there are at the very least 20000 monsters in the whole Underground). Asgore, meanwhile, ''was'' prepared to fight... a human. And by the time they met him, Frisk no longer looks like a human. And also, the worst neutral ending (if we stop Genocide at last moment possible by killing all but one monsters in Core and then killing MTT) has Alphys become queen — so she clearly didn't kill herself.
* After taking Frisk's soul at the end of Genocide Route, Chara does a reset. Not just any reset, but True Reset (as evidenced by Flowey not remembering anything rather than only remembering the events before his death, which is what happens if we kill him on Neutral Route). It's never outright stated, but very strongly implied that Frisk doesn't remember True Resets despite remembering normal ones. As if [[YourSoulIsMine having their soul]] [[DemonicPossession and body stolen and then being]] ForcedToWatch [[AndIMustScream as their friends die at their hand]] wasn't bad enough, they have their soul and body stolen and then are forced to watch as their friends die at their hand ''while having no idea what they did to deserve this.'' YMMV about if this makes their punishment more or less severe.
** An alternative reading of No Mercy, one more sympathetic to the First Fallen, is equally horrific: Chara, resurrected but powerless and drifting along behind the Eighth Human, has been helplessly watching as ''Frisk'', under ''your'' control, murders the beloved subjects Chara themself was willing to die for — beginning with the mother Chara was probably closest to out of any monster except Asriel, given their shared speech patterns. Watching someone systematically hunt down and butcher, not just your relatives, but ''your entire adoptive nation'' as a member of the royal family, would just about destroy anyone, especially someone we already know was willing to trade their life for monsters' well-being. Chara's speech at the end of Genocide is intended to hammer home the player's attitude of grinding for stats in a detached manner, but it takes on a whole extra dimension of horror in this interpretation: the First Fallen is not literally the player, but ''might have started believing they are'', in a desperate attempt to retain some illusion of control in the face of your unremitting cruelty. This is just one of the aspects of Genocide that keeps this troper up nights.
* Two minor bits about the Mad Dummy:
** If the player is doing a No Mercy route, they'll be so angry that you killed their cousin that they will fuse permanently with the dummy they are possessing and become fully corporeal. They are happy about this, but presumably there are many ghosts who wouldn't be happy about being trapped forever in an object they possessed just because they felt a momentary strong emotion.
** As a direct result of the above, they are no longer a ghost, and can be fought. Napstablook said earlier that one can't truly kill a ghost. If the Mad Dummy had hated you just a little less, you wouldn't have been able to kill them, and [[NiceJobBreakingItHero would have been forced to end the No Mercy run]].
* At the end of a post Genocide True Pacifist run, Chara has everything they could want. They are out of the barrier at last, in full control of Frisk's body and SOUL, in the perfect position to slaughter all of the monsters without any of them knowing it's coming, and can finally go out and ravage the world as they please. However, Chara will still let you Reset the game and makes no attempt to stop you despite the fact that they have no reason to allow it and every reason to want to prevent it. This is because they can't stop you. Even before we get into save file manipulation you can reset everything, True Pacifist, Pacifist, Genocide whenever you want to and Chara can't do a thing about it. Ultimately, for all their fourth wall breaking, Chara is just another NPC like the rest, completely a slave to the whims of the player.
* The track "Respite" at the end of the Pacifist Run seems like a sweet, calming, happy song at first; however, the word "respite" means "a short period of rest or relief from something difficult or unpleasant. So why would the end of an era of suffering for monsters be just a brief moment before utter despair? Because Toby knows that you are going to go reset the game and slaughter everyone. The actual track even has static crackling in the background, reminding the player that this is all just a fabrication to them, just a fleeting moment of joy and satisfaction before they destroy everything. No matter what happens, the fate of these characters will always be in the hands of the player, and most of them don't even realize it.
* If you run from Undyne, she eventually collapses in Hotland due to the hot temperature heating up her armor and overheating her. If you leave Undyne rather than sparing her by giving her water from the tank just a few feet away, she dies of heat exhaustion. Assuming you spared Papyrus earlier, Sans will be sleeping at his sentry station just a short distance away from where this happens, and you even run right past him while being chased by Undyne. Imagine his reaction when he wakes up and sees that Undyne died almost right in front of him while he was sleeping, with the means to save her being in plain view.
* In the True Pacifist Route, everyone except Papyrus is covered in two vines: Papyrus is covered in ''four''. Undyne also mentions that Papyrus is "pretty freakin' tough", Papyrus implies on an aborted Genocide Route that he has Gaster Blasters, and if you keep doing the Neutral Route, Flowey mentions that it took him a while to get bored of Papyrus. Putting all that together, it's implied that [[RageBreakingPoint Flowey fucked up enough to make Papyrus go all-out]], ''[[HorrifyingTheHorror and he was so brutal that Flowey had to be careful with Papyrus and make sure he doesn't do that again]]''.
* It was pointed out above that Sans winks with his right eye on a genocide run, and with his left eye on any other run, because he channels his power through his left eye and isn't letting his guard down. Except, when the camera zooms in on him during the rimshot following his first IncrediblyLamePun, he's winking with his right eye. This happens even if it's the first run you ever do, and have been a pacifist up to that point. And since he turns to face the camera for this, it seems that he's directing a subtle warning at the player to not betray him.
* If you kill Toriel, at one point in Waterfall, Flowey will leave a taunting message in Toriel's voice, [[TheNothingAfterDeath where she is in a dark void and calling for help]]. While this may be just a taunt, remember that in the timeline, Asriel has been dead for years, if not decades or a whole century. He might perfectly know just how the afterlife looks like.
* Flowey makes clear that he's been going back in time countless times... yet suddenly, Frisk falls down out of nowhere, with no warning or that ever hapenning in previous timelines. It's highly likely that while the Underground is being reset, the surface is not. So, if that's the case, God knows just ''what'' year is it on the surface, and how fucked Asgore would be if his plan would ever succeed.
** The whole idea mentioned at the end. Asgore finally claims the final human soul, after countless years, [[HopeSpot and it finally seems like the monsters will be set free]]... but then they are absolutely slaughtered by all the powerful weapons humanity has. Asgore might succeed in commiting genocide, or at least killing the majority of humankind, given that he would be a god, but who knows how big will be the casualties when it comes to the rest of the monsters, assuming any of them would survive. Asgore should have just stayed underground.
[[/folder]]
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FridgeLogic: On the [[Headscratchers/{{Undertale}} headscratchers]] page.
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* During the final boss of a No Mercy run, after you finish off Sans, he'll ask Papyrus if he wants anything from Grillby's, which would be incredibly odd considering that to get the Genocide ending, you'd have to kill Papyrus. Why would Sans do this knowing his brother is dead? Simple, it was his way of peacefully accepting his fate. He said that he knew he couldn't beat you and his last resort was to cause a stalemate and prevent you from attacking; after all, with your high stats, you're basically an unstoppable force of evil that murders practially anyone who stops in its path. So after he gets hit and starts to leak all that ketchup he drank, he realizes he's taken a mortal blow and limps offscreen so you don't see him slowly die. Him asking [[FamousLastWords "papyrus, you want anything?"]] was his way of finally giving in to his approaching death by mentioning his dead brother in the most calm way possible so he remains just as relaxed and cool as he was the entire game. Addressing Papyrus, whom is clearly dead, is him coping with the fact that he failed to stop you by talking to his deceased sibling as if he were making his way to the afterlife to join him.

* It makes sense that Alphys, based on a lizard, has a lab/home in Hotland, the warmest part of the underground. Lizards are, like all reptiles, cold-blooded and need to spend time in the warmth to not freeze to death.

** There's a second reason for it as well. To get the true pacifist ending, [[spoiler:you need access to the true lab, and to get there]] you need to befriend Alphys, which requires befriending Undyne. Undyne's friendship is completely conditional on whether or not you have ever gained EXP — one murder before the friendship sequence and it's LostForever until a reset, and if you murder after the friendship sequence, she stops being your friend and generally acts betrayed, which would presumably cause you to lose favor with Alphys as well even if you've befriended her, locking you out of this ending. [[spoiler:And as others on this page have stated, the time needed to complete the true lab and bonds of friendship you have forged on your journey are both pivotal to Flowey's plan to gather all of the most powerful monsters in one place, which is necessary for him to become Asriel.]]

* If you Check Napstablook's stats while fighting him, they actually react to the narrator's statement that they don't seem to have a sense of humor. If you subscribe to the theory that Chara is the narrator, this would be further evidence in that regard - if any monster could sense the spirit of a dead human, it would probably be a ghost.

* Why does Sans sleep a lot? The kid at Snowed Inn mentions that sleeping raised your HP above max. Since Sans's max HP is only one, one hit would normally kill him. By sleeping a lot, he decreases his chance of dying even accidentally.

* Why is there a RunningGag about the smell of different things in the underground? The sense of smell is the sense that is most linked to memories. If something is memerable, one of the things that you will take note of, at least subconsiously, is the smell of that thing. considering how memerable everything in the underground is, no wonder the smell would be noted quite often.

* The fact that the player character develops a separate, homicidal personality is actually even more of Undertale's meta-commentary on games in general. Certain stereotypes aside, it's likely a player who encounters the Fallen Child isn't actually a killer in real life, or even wants to be; they only are killing everyone in-game just to see how deep the rabbit hole goes, or are probably just fanatical at LevelGrinding. To them, the character they're controlling is a ''different person''. So, that's what the game [[LiteralGenie gives you]]; a VillainProtagonist completely at peace with the idea of killing every living thing in order for a player to see what happens. Chara even refers to themselves in the context of being a player character in a game, as a "demon" that is summoned when their name is called (i.e., when you name them at the beginning of any game) and claiming "Time after time, I will appear. And, with your help. We will eradicate the enemy and become strong. HP. ATK. DEF. GOLD. EXP. LV. Every time a number increases, that feeling... That's me." Hands up; who here thinks such an [[CardCarryingVillain individual]] would [[TheStarscream react badly]] to finally being told "no?" Karma can be a tough old broad, can't she?

* Asriel's final desparate plea to allow him to win during the final battle of a Pacifist Run. Though he uses the name given, some of the things he says could be perceived as being directed towards the player. If the player wins the encounter, that's it. The game is over. This is similar to what Flowey said before consuming everyone's souls just moments ago. Given that Flowey and Asriel are the same person, this is the same idea coming across in two distinctly different ways: '''''If you win, you stop playing the game.''''' Though many of the characters form some sort of attachment to the player's character, it's almost as if Asriel/Flowey have formed an actual attachment to the '''player themselves''', and desperately want the player to keep playing the game for that reason.

* Flowey is the only monster in the Underground capable of bringing even a Pacifist player's HP to 1, and he takes several swipes by Chara to destroy. This is because Flowey is not a monster or a human and thus not subjected to the same rules. He's more of a Amalgamate without a SOUL, or a flower possessed by a monster rather than a monster himself. In Undertale monsters are so weak to humans because they possess almost no actual physical matter, being made up of magic, while humans are made up of physical matter almost entirely. As such, Flowey is significantly more powerful and takes more to kill because he's made up of much more physical matter than any other being in the Underground besides the player themselves.

** If you backtrack after being guided by Toriel, you'll discover that the spike puzzle actually isn't dangerous — they just act as walls. However, Toriel has a perfectly good reason to be worried about things that ''seem'' harmless, because the Fallen Child died after (intentionally) poisoning themselves by eating buttercups.

** Similarly, determination is the power of unflinching resolve that persists against all odds. The word can also be read as "de-termination", which means ''negation of death.'' It is the in-game power letting a SOUL do just that. This double meaning aptly describes those who refuse to die, such as Frisk and ''the player themselves''.

** Another interpretation could be that, at least in the ''Undertale'' universe, anime ''is'' real. Think about it for a moment: the player character is a {{determinator}} capable of shrugging off death simply by refusing to die and finds themselves in a world where both magic and monsters exist. The backstory speaks of an [[GreatOffscreenWar ancient war]] between the humans and monsters which eventually led to the latter being sealed underground for what was probably centuries at least. The final battle of the Neutral and Pacifist Routes involves the tragically villainous antagonist gaining the power of an eldritch abomination/outright godhood only to be bested by the [[DavidVersusGoliath seemingly inferior protagonist]]. A well-meaning, but misguided scientist ends up creating horrific (though largely harmless) chimeric beings due to her research into ways to overcome death [[GoneHorriblyRight going horribly right]], and also ends up creating the BigBad the same way. And then, of course, there's Undyne herself. While she may have been largely inspired by the anime Alphys showed her, she definitely fits the bill for a StockShonenHero. Oh, and there's time travel with all the [[TimeyWimeyBall complex goodness]] that entails. At this point, you aren't really lying when you tell her anime is real. After all, you're living in one.

* Mad Dummy is a sort of [[EvilCounterpart meaner counterpart]] to Undyne. Undyne represents anger used productively, filling your good deeds with passion and keeping you determined. Mad Dummy's anger blinds themselves and distances them from others. Mad Dummy eventually becoming Undyne's training dummy is a metaphor for productive anger triumphing over destructive anger.

** The entire twist that the child intentionally had themselves killed by eating fresh, non-dried Buttercups, or Ranunculus. Poisonous to cattle, stock, and basically any normal living person, the symptoms of ingesting a buttercup are downright awful, to say the least. All to probably make their own demise as horrifying and traumatizing as possible to their adoptive family. If that isn't disturbing enough, Asriel and the Child 'accidentally' fed Asgore buttercups instead of cups of butter in a butterscotch pie, which makes you wonder if the Child basically tried assassinating him previously via illness just to disrupt everything.

* It was pointed out above that Sans winks with his right eye on a genocide run, and with his left eye on any other run, becaus he channels his power through his left eye and isn't letting his guard down. Except, when the camera zooms in on him during the rimshot following his first IncrediblyLamePun, he's winking with his right eye. This happens even if it's the first run you ever do, and have been a pacifist up to that point. And since he turns to face the camera for this, it seems that he's directing a subtle warning at the player to not betray him.

* If you, during a Neutral run, only kill beings in the Ruins, Undyne still calls you out on having killed monsters. How on Earth could she know that? The Ruins have been sealed off from the rest of the underground for ages, no-one has been able to enter or exit them for ages (well, except for incorporeal beings like ghosts, tiny crawlies like spiders, and borrowing beings like Flowey), so no-one could've told her about it, riiight? ... Do you remember who else is aware of what you did in the Ruins? The Mad Dummy, Undyne's personal and very chatty training dummy and the cousin of the ghost / dummy you meet in there. Do you remember who's neighbors with Undyne? Napstablook, who, if you do a Genocide run, escapes as you approach him, proving that even though he's just lying there, he is ''very much'' aware of what you're doing in the Ruins. With that in mind, is it ''really'' so very odd that Undyne is well informed about your actions in the prologue?

** If the player is doing a No Mercy route, he'll be so angry that you killed his cousin that he will fuse permanently with the dummy he is possessing and become fully corporeal. He is happy about this, but presumably there are many ghosts who wouldn't be happy about being trapped forever in an object they possessed just because they felt a momentary strong emotion.
** As a direct result of the above, he is no longer a ghost, and can be fought. Napstablook said earlier that one can't truly kill a ghost. If the Mad Dummy had hated you just a little less, you wouldn't have been able to kill him, and [[NiceJobBreakingItHero would have been forced to end the No Mercy run]].

* Examining the dog couple's hut in Snowdin, you'll find coloured definitions of the threat levels — White, Blue, and Red; however, the word Red is actually coloured green. Dogs are red-green colourblind.