History Characters / UndertaleSans

* BadBedroomBadLife: If the player follows a specific set of actions to get the key to open it, Sans' bedroom is revealed to be a complete mess, including a self-sustaining trash tornado, a jury-rigged light fixture, and an unmade bed. Sans is pretty apaphetic to what happens around him, so not bothering to keep his room tidy is in-line with his behavior.

* AlphaStrike: Sans does not mess around on the [[KillEmAll Genocide Route]]. His first attack is a strong contender for being his most powerful — a brutal gauntlet of [[spoiler:GravityScrew, SpikesOfDoom, and BeamSpam using [[WaveMotionGun Wave Motion Guns]] that can and most likely will waste you within seconds]]. [[spoiler:To top it all off, [[NoFairCheating he's also the only enemy in the game that gets the first turn]].]]

** Pester Flowey enough by completing multiple Neutral Runs, and he will eventually tell you to stay away from 'Smiley Trashbag' for [[spoiler:causing him [[OffscreenMomentOfAwesome 'more than his fair share of resets']]]]. [[spoiler:Then you try to [[KillEmAll walk in Flowey's footsteps]], and ''boy'' are you in for a surprise.]]

* GodzillaThreshold: ''You''. The one thing that can make Sans get off his ass and actually try is the threat of [[spoiler:a player character about to KillEmAll and poison every timeline in the game]].

* ThresholdGuardian: He blocks your path in the Final Corridoor, and will judge you for all you have done across the game. If you pass with flying colors, he will basically say 'nice work'. If you've been engaging in VideoGameCrueltyPotential, especially if you kill Papyrus, he has some PlayerPunch to deliver. If you've been violent without going into outright KickTheDog territory, he basically leaves you to judge yourself unless you press the issue. [[spoiler:And if you've been going for the [[KillEmAll No Mercy]] route, he gets off his ass to stop you '' personally.'']]

* VideoGameCrueltyPunishment: He will judge you near the end of your journey, and he has some [[PlayerPunch choice words]] should you engage in VideoGameCrueltyPotential. [[spoiler:And if you've been going for the KillEmAll route, he bars your path as ''the'' single toughest boss in the game.]]

* WalkingSpoiler: There's quite a bit more to Sans than just the joke-loving skeleton you meet early on. Those avoiding spoilers take heed: even glancing at fanart of Sans will almost certainly give away something about his character. And, y'know, there are many {{spoiler}} marks here for a reason. [[spoiler:To sum up, Sans is one of the two {{Fourth Wall Observer}}s, '''the''' FinalBoss of the [[KillEmAll Genocide Route]] plus [[CombatPragmatist how he fights]], and the fact [[IWarnedYou he warns you if you win]] that it's the PointOfNoReturn.]]

* VehicleBasedCharacterization: During the credits, Sans rides a tricycle faster than Papyrus riding a car. This little detail shows his CrouchingMoronHiddenBadass personality.

* AmbiguousDisorder: While his laziness and apathy to almost everything around him (that isn't Papyrus) is played for laughs more often than not, a lot of what he does and says rings eerily close to someone suffering from depression. [[spoiler:In the final Pacifist-route fight, his lines notably aren't hostile as with the rest of your brainwashed friends, but just straight-up hopeless and sorrowful, such as his line in which he advises you to "just give up. i did." In his boss fight in the genocide route, he even discusses this, briefly musing if his refusal to do anything stems from the knowledge that it won't matter anyway or if he's just actively looking for an excuse to be lazy.]]

----

* BeamSpam: He liberally uses his [[WaveMotionGun Gaster Blasters]] to fight. Taken UpToEleven in his penultimate attack, where he fires in excess of ''100'' beams in less than 10 seconds.

* HeroicSafeMode: One could say this is his default mode during [[spoiler:all runs]]. In Neutral and Pacifist, he [[BeneathTheMask acts friendly]] towards the player to keep his world (especially [[LivingEmotionalCrutch his brother]]) safe and stalks them around to keep tabs on their kill count. [[spoiler:If you kill his brother or start a Genocide run, this mode is taken UpToEleven; he stops trying to befriend you and only focuses on trailing your actions, until the Judgement Hall where he either gives his judgement with very clear TranquilFury or outright fights you to save the world.]]

* MinoredInAssKicking: Sans would very much prefer to [[TheSlacker sit around and make jokes all day]], only stepping into your adventure once in a while to share food or friendly advice with you, but if pushed far enough, [[spoiler:[[UpToEleven Sans becomes the single most dangerous monster in the underground]]]].

* SquishyWizard: While all monsters are this to some degree, Sans takes this trope UpToEleven:

* TranquilFury: Sans, of course, is a very chill skeleton... and the most chilling thing about him is his no-nonsense font and lightless sockets if you manage to piss him off. Taken UpToEleven during [[spoiler:the final battle with him, where he's ''still'' grinning with one hand in his pocket as he ''pulverizes'' you with the other one, one of his eyes literally flashing with rage]].

* AttackDrone: Uses giant, floating, [[spoiler:demonic skulls called "Gaster Blasters" in his battle.]] [[spoiler:They fire [[WaveMotionGun wave motion beams]].]]

* AttackDrone: Uses giant, floating, [[spoiler:demonic skulls]] called "Gaster Blasters" in his battle. [[spoiler:They fire [[WaveMotionGun wave motion beams]].]]

* OptionalBoss: Zigzagged. Sans ''is'' required to finish a No Mercy run, but the No Mercy run itself is ''not'' required ([[VideoGameCrueltyPunishment nor is it recommended]]) to get True Pacifist or even Neutral. Just getting to Sans requires killing every monster in the Underground, which is easier said than done due to the increasingly sporadic random encounters and [[UpgradedBoss Undyne the Undying]]. By contrast, Omega Flowey and [[spoiler:Asriel]] are much more straightforward with how they're fought, and both have to be beaten to achieve True Pacifist.

* {{Superboss}}: Sans' fight is completely optional on most runs, and getting to him takes a lot of time and patience required to kill everyone in the Underground. However, once you meet the criteria for his fight, he's easily the hardest boss in the entire game with his attacks doing one damage per frame, said frames causing DamageOverTime, and an assortment of quick attack patterns that include [[WaveMotionGun Gaster Blasters]], his brother's [[GravityScrew Blue Attack]], and [[CameraScrew messing with your screen]] for one heck of a bad time.

* BigBrotherMentor: If the player goes strictly for the Pacifist Run, Sans will fill this role for the Human Child, occasionally giving some discreet assistance in the form of dropping hints, giving emotional support, and providing levity where he thinks its warranted.

[[folder:A-B]]

[[/folder]]

[[folder:C-E]]

[[/folder]]

[[folder:F-H]]

[[/folder]]

[[folder:I-M]]

[[folder:N-R]]

[[/folder]]

[[folder:S-T]]

[[/folder]]

[[folder:U-Z]]

* GlowingEyesOfDoom: One of Sans's eyes glows as he uses various abilities during his battle, like Asgore.

->''"maybe [sic] it's a little strange, but sometimes... it's nice to have someone call you out on being lazy. even though nothing could be further from the truth."''

-->'''Sans:''' by [sic] the way... i [sic] was going to say something, but i [sic] forgot.

-->'''Sans:''' [[spoiler:sounds [sic] strange, but before all this i [sic] was secretly hoping we could be friends]].

-->'''Sans:''' heh [sic] heh heh heh...all right. well [sic], here's a better question. [[DontMakeMeDestroyYou do [sic] you wanna have a bad time?]] 'cause [sic] if you take another step forward...you are REALLY not going to like what happens next.

--->'''Sans:''' it's [sic] a beautiful day outside. birds are singing, flowers are blooming. on days like these, kids like you... [[spoiler:'''[[LetsGetDangerous Should be burning in hell]]'''.]]

--->'''Sans:''' hmm [sic]. that [sic] expression...that's the expression of someone [[spoiler:who's died thrice in a row]]. ''[{{beat}}]'' hey, what comes after "thrice," anyway? [[PrepareToDie wanna help me find out?]]

-->'''Sans:''' it's [sic] a beautiful day outside. birds are singing, flowers are blooming... on days like these, kids like you... [[spoiler:[[PreAsskickingOneLiner Should be burning in hell.]]]]

-->'''Sans:''' geeettttttt [sic] dunked on!!

-->'''Sans:''' huh [sic]. always wondered why people never use their strongest attack first.

'''Sans:''' i [sic] think that's called... sleeping.

--->'''Sans:''' heh [sic] heh heh... ya get it? [[spoiler:i [sic] know i [sic] can't beat you. one [sic] of your turns... you're just gonna kill me. so [sic], uh. i've [sic] decided... it's not gonna BE your turn. ever [sic]. i'm [sic] just gonna keep having MY turn until you give up. even [sic] if it means we have to stand here until the end of time. capiche [sic]?]]

'''Sans:''' ok [sic].\\

'''Sans:''' ok [sic].\\

'''Sans:''' ok [sic].\\

'''Sans:''' ok [sic].\\

'''Sans:''' didn't [sic] you just say not to bring it back to my room?\\

-->'''Sans:''' geeettttttt [sic] dunked on!!

--->'''Sans:''' it's [sic] a beautiful day outside. birds are singing, flowers are blooming. on days like these, kids like you... [[spoiler:'''Should be burning in hell.''']]

-->'''Sans:''' all [sic] i [sic] know is...seeing what comes next...i [sic] can't afford not to care anymore.

-->'''Sans:''' [[spoiler:that's [sic] the expression of someone who's died five times in a row. convenient [sic], huh? that's [sic] one for each finger. but [sic] soon... '''you'll need a cool mutant hand to count all of your deaths.'''\\
that's [sic] the expression of someone who's died six times in a row. that's [sic] the number of fingers on a mutant hand. '''you'll [sic] need to find a mutant hand with even more fingers.'''\\
that's [sic] the expression of someone who's died seven times in a row. hey, that's good. seven's [sic] supposed to be a lucky number. who [sic] knows, maybe you'll hit the jackpot... '''and that number will multiply tenfold.'''\\
that's [sic] the expression of someone who's died eight times in a row. that's [sic] the number of fingers on a spider. '''wait [sic], don't spiders have legs?''']]

-->'''Sans:''' ''"i [sic] always thought the anomaly was doing this cause they were unhappy. and [sic] when they got what they wanted, they would stop all this... but that's ridiculous, right? yeah [sic], you're the type of person who won't EVER be happy."''

--->'''Sans:''' "what [sic]? haven't [sic] you seen a guy with [[CallBack three]] jobs before?"

-->'''Sans:''' geeettttttt [sic] dunked on!!

-->'''Sans:''' it's [sic] a beautiful day outside. birds [sic] are singing, flowers are blooming. on [sic] days like these, kids like you... [[spoiler:'''Should be burning in hell.''']]

-->'''Sans:''' you [sic] can't understand how this feels. knowing [sic] that one day, without any warning... [[spoiler:it's all going to be reset. look [sic]. i [sic] gave up trying to go back a long time ago. and [sic] going to the surface doesn't really appeal anymore either. 'cause [sic] even if we do... we'll just end up back here without any memory of it, right?]] to [sic] be blunt... it makes it kinda hard to give it my all.

-->'''Sans:''' [[spoiler:just [sic] give up. i [sic] did. why [sic] even try? you'll [sic] never see them again.]]

-->'''Sans:''' hey, [[SincerityMode i really respect what you did back there. thanks.

-->'''Sans:''' hey [sic], [[SincerityMode i [sic] really respect what you did back there. thanks [sic]]].

--->'''Sans:''' heh [sic] heh heh heh...all right. well [sic], here's a better question. [[DontMakeMeDestroyYou do [sic] you wanna have a bad time?]] 'cause [sic] if you take another step forward...you are REALLY not going to like what happens next.

->''"maybe it's a little strange, but sometimes... it's nice to have someone call you out on being lazy. even though nothing could be further from the truth."''

-->'''Sans:''' by the way... i was going to say something, but i forgot.

* AnnoyingYoungerSibling: Inverted; as much as he loves his brother Papyrus, he still finds great delight in annoying the ever-loving daylights out of him.

-->'''Sans:''' [[spoiler:sounds strange, but before all this i was secretly hoping we could be friends.]]

---> '''Sans:''' heh heh heh heh...all right. well, here's a better question. [[DontMakeMeDestroyYou do you wanna have a bad time?]] 'cause if you take another step forward...you are REALLY not going to like what happens next.

--->'''Sans:''' it's a beautiful day outside. birds are singing, flowers are blooming. on days like these, kids like you... [[spoiler:'''[[LetsGetDangerous Should be burning in hell]]'''.]]

--->'''Sans:''' hmm. that expression...that's the expression of someone [[spoiler:who's died thrice in a row]]. ''[{{beat}}]'' hey, what comes after "thrice," anyway? [[PrepareToDie wanna help me find out?]]

-->'''Sans:''' it's a beautiful day outside. birds are singing, flowers are blooming... on days like these, kids like you... [[spoiler:[[PreAsskickingOneLiner Should be burning in hell.]]]]

* BigBrotherWorship: {{Inverted}}. Sans makes it clear on many occasions how cool he genuinely finds Papyrus, for all he messes with him.

-->'''Sans:''' geeettttttt dunked on!!

'''Sans:''' i think that's called... sleeping.

--->'''Sans:''' heh heh heh... ya get it? [[spoiler:i know i can't beat you. one of your turns... you're just gonna kill me. so, uh. i've decided... it's not gonna BE your turn. ever. i'm just gonna keep having MY turn until you give up. even if it means we have to stand here until the end of time. capiche?]]

'''Sans:''' ok.\\

'''Sans:''' ok.\\

'''Sans:''' ok.\\

'''Sans:''' ok.\\

'''Sans:''' didn't you just say not to bring it back to my room?\\

** He is really, ''really'' lazy, even if the cause of that is up for debate. While it's played for laughs every time it comes up for the most part, [[spoiler:he winds up exhausted should the player make it all the way to the end of his final barrage in No Mercy. From there, he starts to doze off...]]

-->'''Sans:''' geeettttttt dunked on!!

--->'''Sans:''' it's a beautiful day outside. birds are singing, flowers are blooming. on days like these, kids like you... [[spoiler:'''Should be burning in hell.''']]

-->all i know is...seeing what comes next...i can't afford not to care anymore.

-->[[spoiler:that's the expression of someone who's died five times in a row. convenient, huh? that's one for each finger. but soon... '''you'll need a cool mutant hand to count all of your deaths.'''\\
that's the expression of someone who's died six times in a row. that's the number of fingers on a mutant hand. '''you'll need to find a mutant hand with even more fingers.'''\\
that's the expression of someone who's died seven times in a row. hey, that's good. seven's supposed to be a lucky number. who knows, maybe you'll hit the jackpot... '''and that number will multiply tenfold.'''\\
that's the expression of someone who's died eight times in a row. that's the number of fingers on a spider. '''wait, don't spiders have legs?''']]

* TheReasonYouSuckSpeech: Delivers one to the player in the second stage of his battle, questioning why they want to destroy his world so badly. [[spoiler:Given that this happens after his attempts to stop the player through trickery and just plain making the battle difficult have failed, it doubles as an attempt to BreakThemByTalking.]]
-->''"i always thought the anomaly was doing this cause they were unhappy. and when they got what they wanted, they would stop all this... but that's ridiculous, right? yeah, you're the type of person who won't EVER be happy."''

--->'''Sans:''' "what [sic]? haven't you seen a guy with [[CallBack three]] jobs before?"

-->'''Sans:''' hey, [[SincerityMode i really respect what you did back there. thanks.]]

-->'''Sans:''' geeettttttt dunked on!!

-->'''Sans:''' it's a beautiful day outside. birds are singing, flowers are blooming. on days like these, kids like you... [[spoiler:'''Should be burning in hell.''']]

-->'''Sans:''' you can't understand how this feels. knowing that one day, without any warning... [[spoiler:it's all going to be reset. look. i gave up trying to go back a long time ago. and going to the surface doesn't really appeal anymore either. 'cause even if we do... we'll just end up back here without any memory of it, right?]] to be blunt... it makes it kinda hard to give it my all.

-->'''Sans:''' [[spoiler:just give up. i did. why even try? you'll never see them again.]]

--->'''Sans:''' "what? haven't you seen a guy with [[CallBack three]] jobs before?"

* CombatPragmatist: He pulls just about every dirty trick in the book, and constantly breaks the rules of the combat system to compensate for his low stats. Some examples include [[BeginWithAFinisher launching a powerful attack right at the start of the battle]], dodging attacks, ignoring MercyInvincibility, and hitting you ''during menu selection''. In his second phase, he's also able to change attack patterns on the fly just to screw with you. On the first and every subsequent time you reload after being defeated by him, he also gains the ability to randomly interrupt his own opening speech to catch you off-guard with his first attack. He tries [BreakThemByTalking breaking the player character by talking]], and even pulls an ISurrenderSuckers before delivering a OneHitKill.

* BadassBoast: He gives several such boasts before and during [[spoiler: his boss fight]]:

--> '''Sans:''' it's a beautiful day outside. birds are singing, flowers are blooming... on days like these, kids like you... [[spoiler:[[PreAsskickingOneLiner Should be burning in hell.]]]]

* CombatPragmatist: He pulls just about every dirty trick in the book, and constantly breaks the rules of the combat system to compensate for his low stats. Some examples include [[BeginWithAFinisher launching a powerful attack right at the start of the battle]], dodging attacks, ignoring MercyInvincibility, and hitting you ''during menu selection''. In his second phase, he's also able to change attack patterns on the fly just to screw with you. On the first and every subsequent time you reload after being defeated by him, he also gains the ability to randomly interrupt his own opening speech to catch you off-guard with his first attack. He also delivers some absolutely ''brutal'' [[BreakingSpeech trash talk]] throughout the fight (and subsequent attempts) to remind you just how much of a scumbag you are, and even pulls an ISurrenderSuckers before delivering a OneHitKill.
-->'''Sans:''' huh. always wondered why people never use their strongest attack first.

---> [[spoiler:''He can't keep dodging forever.'']]

---> '''Sans:''' "what? haven't you seen a guy with [[CallBack three]] jobs before?"

* BewareTheNiceOnes: An extremely chill and amiable guy, Sans is liked by everyone who knows him (except [[TheSociopath Flowey]], obviously) and treats you like an old friend mere seconds after you meet him. It usually takes a ''lot'' of effort to get Sans legitimately angry with you, but if you do… at best, [[spoiler:[[WhatTheHellPlayer he'll call you out for the dirty scumbag you are]]]], and at worst, [[spoiler:''say your prayers and hope it's over quickly'']].

** The guy's already [[DespairEventHorizon so jaded at this point]] that you'd think there'd be no way to break him further, but there ''is'' one surefire way: find the nerve to [[LivingEmotionalCrutch kill his little brother]]. Do that, and Sans will just… [[spoiler:stop being in the game. ''Completely''. Off-screen, he plunges into some kind of HeroicBSOD and/or HeroicSafeMode, never talking to anybody and stalking you in silence, focusing on your general kill count. He'll only show up near the very end in full TranquilFury mode, and if you reach an ending where you can get him to talk to you again afterwards, he makes it very clear that you really, ''really'' hit him in the one place that still hurts]].

** There is nothing he can do to stop [[spoiler:the constantly repeating time loop he's trapped in]], so he eventually just numbed himself to all of it. Unless the player carries out a Genocide run, he usually just shrugs off any deaths that happen and mocks you in the end for causing them, [[spoiler:knowing that it'll be reset anyway]]. The one and only thing you can do that really manages to get to him is [[LivingEmotionalCrutch murder his beloved brother]], which sends him into a full-on HeroicSafeMode at worst. And if you do go full Genocide, well… [[spoiler:he may ''pretend'' to take it in stride when he dies, knowing the entire world is about to be destroyed, but [[BrokenSmile the look in his eyes gives him away]]]].

* TheConscience: Sans is literally ''your'' moral compass. He's a reflection on everything you do during your journey through the Underground. He'll [[YouBastard chastise you if you kill]] randomly/indiscriminately, or he'll be your best friend ever if you're benign. Kill everyone, and watch out, [[BewareTheSillyOnes he'll come down upon your wickedness like a ton of bricks]]. Even during the final fight, he's not fighting for the Underground's sake… ''you've already destroyed everything he knew and loved''. [[spoiler:He's fighting for ''your'' sake as well, knowing full well that if you successfully get past him, you're eternally damned, as the Fallen Child will claim your soul.]]

* DespairEventHorizon: He's goofy and a PungeonMaster, but underneath that big grin, Sans… Sans is not well. [[spoiler:Living with the knowledge that at any second, your life can be irrevocably snatched away from you, for every minute of the day tends to do that to a guy.]]

* DidntSeeThatComing: Sans is savvy enough to keep his guard up at all times, even when he's offering reconciliation or ''sleeping''… [[spoiler:But he didn't expect you to be able to attack two times in a single turn.]] [[WideEyesAndShrunkenIrises The look on his face]] says it all.

** Most infamously, when he uses his "special attack", he says "here goes nothing." What happens next is… [[spoiler:[[ExactlyWhatItSaysOnTheTin literally nothing]]. As in Sans ''refuses'' to end his turn, since he knows that your next move will be his last. So he simply waits, hoping that you'll get so bored that you'll give up and quit. Sadly for Sans, he gets ATasteOfHisOwnMedicine…]]

** He is really, ''really'' lazy, even if the cause of that is up for debate. While it's played for laughs every time it comes up for the most part, [[spoiler:he winds up exhausted should the player make it all the way to the end of his final barrage in No Mercy. From there, he starts to doze off…]]

** When you first enter Snowdin, there's a large branch in the path that's "too heavy to move", implying that it's fairly large. Once Sans starts following you through the forest, you hear a loud cracking sound. If you backtrack a bit, you'll notice that the branch has been ''snapped in half''. [[spoiler:Considering Sans and the Human Child are about the same size and a skeleton is probably much lighter than a human, Sans must have crushed it with magic… and demonstates this ability to you first-hand during his fight, where he flings your soul violently against the walls, ceiling, and floor.]]
** During the epilogue of the GoldenEnding, Papyrus got his wish of driving a car on the highway. Which then got outsped by Sans on a tricycle. Was Papyrus just driving ''really'' slowly? (But then again, he's on the highway.) [[spoiler:…Or does Sans have hidden talents?]]

* GameFace: Sans is always grinning, constantly looking around to make aside glances while he talks, giving him a cheerful, animated feel. [[spoiler:When his eyes disappear and he just ''stares'' straight at you with empty, pitch-black eye sockets, you know things have just gotten real. And when his left eye starts [[GlowingEyesOfDoom glowing]]… start praying, for all the good it will do.]] On the flip side, [[spoiler:his eyelights also disappear at one point in a Pacifist run, when he tells you his secret secret codeword: "I'm the legendary fartmaster.", implying confiding such is SeriousBusiness]].

* IFellForHours: Weaponized for his penultimate attack, combined with GravityScrew and SpikesOfDoom. And it's not even the deadliest part of said attack. At first, the attack looks admittedly quite funny, with Sans pulling various poses as the player’s soul flies past… until it takes a decisive swerve when the last sprite of Sans seen in this segment of the attack features him with dark eye sockets.

* ISurrenderSuckers: Do you enjoy sparing people only to kill them when their guard is down? Well, if you think [[spoiler:Sans is being sincere when he offers a truce to a mass murderer like you… [[KarmicDeath prepare to get dunked on.]] Why would he let you go so easily if [[ApocalypseHow you're going to end everything]]?]]

* NonchalantDodge: Sans can [[spoiler:sidestep your attacks]], and wonders why no one else tries it… But then it's subverted to disturbing effect when [[spoiler:the Fallen Child takes over [[DiagonalCut and slices him in two despite his attempts to dodge]]]].

** Sans is almost always cracking wise or lazing about, seemingly without a care in the world. Yet he has his moments of gravity, and when it comes time to deliver them, [[GameFace his pupils fade into darkness]], his VoiceGrunting disappears (often taking the background music with it), and he loses his AllLowercaseLetters speaking style. He even changes fonts (he usually speaks in Comic Sans, but switches to the sans-serif 8bitoperator for his serious lines). Also, if it's your fault that Sans finally decides to [[LetsGetDangerous stop being lazy]], well… [[ThisIsGonnaSuck you're gonna have a bad time.]]
** Also, he avoids hard work, even if you kill all the leaders… but his love for his brother is stronger than his sloth. [[spoiler:If Papyrus becomes king, Sans will work really hard for him.]]

* PaintingTheMedium: To start, Sans speaks in comic sans. Secondly, he spends most of the game talking in AllLowercaseLetters… but at random he'll leave his I's capitalized, and he will sometimes use apostrophes correctly but sometimes won't. Yes, Sans is so lazy he can't even use AllLowercaseLetters consistently. Or to put it another way, Sans speaks like he's ''typing'' but is too lazy to type properly; now remember that Toby Fox had to type all of Sans' dialogue.

** Alluded to when facing him as a Lost Soul, and explicitly stated [[spoiler:when fighting him on a No Mercy run]]. His knowledge of [[spoiler:the player's and Flowey's interference with the timeline (through saving and resetting), and the belief that things will inevitably be reset again in the future]], has left him exhausted and existentially depressed. It's implied that this also has something to do with the strange machine Sans is working on…
** Sans also displays a degree of self-loathing, most notably in the ending where [[spoiler:you kill all of the important characters and at least one other monster, leaving the Underground utterly bereft of leaders]]. Sans talks about why he didn't take up the throne and explains that it isn't his style, and that he prefers to take things easy… before explaining that that was a joke and the whole mess they're stuck in is exactly what happens when "people like [him]" take it easy.

* SealedEvilInADuel: Attempted. [[spoiler:His 'Special Attack' is simply to start his turn… and never end it.]] He outright says that he intends to just sit there until you get bored and turn off the game. [[spoiler:Unfortunately, he falls asleep after a while, allowing you to finally kill him.]]

* StoppedCaring: He doesn't seem to care about anything aside from bad jokes and his brother. [[spoiler:He's figured out that someone or something has been resetting and manipulating the timeline, and has given up trying to stop them… aside from befriending everyone he meets in the hope that one of them is the source and he can finally make them contented enough to stop.]]

* TranquilFury: Sans, of course, is a very chill skeleton… and the most chilling thing about him is his no-nonsense font and lightless sockets if you manage to piss him off. Taken UpToEleven during [[spoiler:the final battle with him, where he's ''still'' grinning with one hand in his pocket as he ''pulverizes'' you with the other one, one of his eyes literally flashing with rage]].

** When he decides to step in and take action [[spoiler:at the end of Genocide run, he’s pretty much resigned to [[HopelessBossFight his tragic fate]]. But knowing you’re about to destroy the world…]] he just can’t afford to not care anymore. He gives one hell of a final fight with the hopes of getting you to RageQuit or reset to a more merciful game route, but at the end of the day, you have the SaveScumming ability that he has no counter against.

** Both of them are [[ThePrankster pranksters]], [have a talent for imitation, and [[MysteriousWatcher watch for the protagonist in the shadows]]. [[spoiler:Flowey avoids contact, plays cruel pranks on you consisting of giving you a HopeSpot, makes imitations in the same vein (for example, the infamous Echo Flower in Waterfall where he mimics Toriel's voice before taunting you), and takes action [[NiceJobBreakingItHero once you've fought Asgore yourself]] to take the Human Souls for his own benefit. On the other hand, Sans frequently chats with them, [[ThePrankster plays childish pranks on them]][[note]]for example, the telescope prank in Waterfall (though it could be more serious than it seems to be)[[/note]], offers them a dinner where he shows his talent by imitating Toriel, judges them before they meet the King, and [[ThisIsGonnaSuck only takes action if they go too far]].]]

* CombatPragmatist: He pulls just about every dirty trick in the book, and constantly breaks the rules of the combat system to compensate for his low stats. Some examples include [[BeginWithAFinisher launching a powerful attack right at the start of the battle]], dodging attacks, ignoring MercyInvincibility, and hitting you ''during menu selection''. In his second phase, he's also able to change attack patterns on the fly just to screw with you. He also delivers some absolutely ''brutal'' [[BreakingSpeech trash talk]] throughout the fight (and subsequent attempts) to remind you just how much of a scumbag you are, and even pulls an ISurrenderSuckers before delivering a OneHitKill.

* CombatPragmatist: He pulls just about every dirty trick in the book, and constantly breaks the rules to compensate for his low stats. Some examples include [[BeginWithAFinisher launching a powerful attack right at the start of the battle]], dodging attacks, ignoring MercyInvincibility, and hitting you ''during menu selection''. In his second phase, he's also able to change attack patterns on the fly just to screw with you. He also delivers some absolutely ''brutal'' [[BreakingSpeech trash talk]] throughout the fight (and subsequent attempts) to remind you just how much of a scumbag you are, and even pulls an ISurrenderSuckers before delivering a OneHitKill.