Similarly in the Darker and EdgierAdvance Wars: Days of Ruin, the defeated Admiral Greyfield tells Lin she'll be just as bad as him if she kills him, although in this case, he's just deliberately invoking the trope in a panicked and desperate (yet strangely Genre Savvy) attempt to save his own life. She admits that he's completely right, then shoots him anyway.
Similarly, Waylon does this to Will in their final battle. Will admits it, but informs Waylon that this doesn't give him the moral high ground.
In Mega Man Zero 4, Dr. Weil desperately bluffs Zero and tries to convince him that killing Weil would be stooping to his level of villainy. In an unorthodox move, Zero kills him anyway, making note at how he never considered himself a hero to begin with.
Though never conversed, a much sadder example involving White and Grey Morality exists with Zero and Harpuia, given how both are fighting for the same goal.
Done rather sadly in Mega Man 2: The Power Fighters, where Mega Man's solo ending had Dr. Wily pointing out Mega Man's senseless destruction of robots in the act of peace for humans and robots. This puts Mega Man in guilt long enough for Wily to escape by the time he is cheered up by his friends.
Inverted in Mega Man Star Force, with Mega Man Geo-Omega (the protagonist, and a good guy) telling Harp Note that he is just like her, in an effort to get her to join forces with him. Not only does it work, but it is actually true as both of them have previously lost a parent.
Metal Gear has Big Boss, an antagonist whose ideology of perpetual, honourable warfare lingers on through his unkillable son, Liquid Snake. It all seems the usual completely bonkers nonsense, until you're put into his shoes at the start of the third game and get to see what he went through before he formed the Foxhound unit and started trying to create a military nation to leave soldiers free to do battle. He suffers through the same betrayals and manipulation that the series protagonist, Solid Snake, has gone through, and at the end is just as alienated and bitter. It leaves a potent, unstated message about how someone's past experiences don't control their future.
A clearer example is towards the end of the first Metal Gear Solid. Liquid is talking about bringing about his father's vision of a return to warfare. When Snake claims that he doesn't want that kind of a world, Liquid's response is a CMOA.
Liquid: So why are you here, then? Why do you continue to follow your orders while you superiors betray you? Why did you come here? (Snake fails to answer.) Well... I'll tell you then. You enjoy all the killing, that's why.
Psycho Mantis does give a similar statement to Solid Snake. Well, sort of...
Psycho Mantis: I've seen true evil. You, Snake. You're just like the Boss... no, you're worse.
A more direct use of this was shortly after Psycho Mantis revealed what he did to the village:
Solid Snake: Are you saying you burned your village down to bury your past? Psycho Mantis: I see that you...have suffered the same trauma. (Mantis laughs feebly.) We are truly the same, you and I... The world is a more interesting place... with people like you in it. I never agreed with the Boss's revolution. His...dreams of world conquest do not interest me. I just wanted an excuse to kill as many people as I could.
Metal Gear Rising: Revengeance has most of the villains relating themselves to Raiden. It's even present in the lyrics to the final boss's theme music.
"Standing here, I realize, you are just like me trying to make history." "I've cut my own path, you've followed your wrath, but maybe we're both the same."
In Assassin's Creed I, mad executioner Majd Addin attempts to pull this on Altair, explaining that they aren't so different and that he would have done the same were he in Addin's position. Altair's response is to agree that indeed, he once may have, until he discovered what awaits such people - demonstrated by stabbing Addin in the neck.
In Assassin's Creed II, the first mark (who got Ezio's father and brothers executed) makes the excuse, "You would have done the same...to save the ones you love." Ezio agrees... so he goes through with the killing.
In Oni, at the end of the Rooftops sequence's ninja bossfight, the main character exclaims that she has nothing in common with him - then breaks his neck with her boot.
Mukade: Does your blood burn when you kill? Mine does. Konoko: Stop it... Mukade: We writhe inside as we are torn apart to make way for what we will become. Surrender to it... Let the bliss of oblivion free you all your doubts and fears! Konoko: You're one of Muro's thugs, nothing more! Mukade:(laughs) We shall see... (Konoko beats the crap out of Mukade) Konoko:(thinking) Griffin encouraged me not to look too deeply into my past. Seems like there was a lot he didn't want me to know... I could feel the ninja and I know he could feel me. Why? What am I becoming? Are we the same...? No, I have nothing in common with him. (kills Mukade)(aloud)Nothing!
Panda King: Why should you care if I bury a few worthless villages in snow? You are a thief, just like me.
Sly: No that's only half true. I am a thief - from a long line of master thieves. While you... You're just a frustrated fireworks artist turned homicidal pyromaniac!
In the third game, Big Bad Dr. M uses this with Bentley because they were/are the smart guys of their group, with Dr. M stating that Sly's talks of Friendship is just an inherent Cooper lie. Near the end, Dr. M grudgingly admits that Sly's and Bentley's friendship might be real after all.
While it does depend on how you roleplay The Hero, your half-brother Sarevok in Baldur's Gate is implied to have several similarities to you. Perhaps the most damning evidence is a vision in Throne of Bhaal which shows that, had your positions been reversed, you each would have ended up exactly like the other. You can't fulfill this trope any more than that.
In an example with two companions, Korgan makes this argument to Valygar, since both are kinslayers. Valygar points out that his own motivation was to stop his crazed mother from killing people with Black Magic, while Korgan went on a murder spree to be the sole claimant to an inheritance.
Korgan: Killing is killing, my lanky friend. Sugar-coat it all ye like but when we go to family reunions we both go alone.
He has a mask which is never removed, he is shrouded in mystery, needs to sneak around lest he get shredded, and punishes enemies who let him get behind them. This character is also voiced by Dennis Bateman. Now which Team Fortress 2 class are we talking about, the Spy or the Pyro with a Backburner?
What's the difference between a Medic and a Spy? The team that's yelling at him.note This is because players will call for their own team's Medics when low in Health, and identify disguised enemy Spies to other teammates by shouting, "That *class* is a Spy!".
Kills by targeting weak points from concealment and prides himself on professionalism. Sniper or Spy?
A somewhat quiet but highly intellgent man—you might think from his accent that he's not that clever, but as it turns out, he actually holds a doctorate. A bit particular with his guns...okay, very particular about his guns and is often distrustful of other people touching them. A great defensive class but extremely vulnerable to Spy attack, and can also heal others as a side benefit. Bald, chin stubble, and normally wears clothing that obscures their uniform shirt, which have emblems of their melee weapons on them. Was that a brief summation of the Heavy or the Engineer?
A loud, often entertaining warrior who specializes in explosives. Can wield a sword, but is just as likely to blow something up. Possibly himself, by exploding his primary weapon under his feet and launching himself into the air. Can swap one of his other weapons for equipment to support his tactics—or a parachute. Definitely made to worry Engineers and a great healing buddy for a Medic. Has some distinct vision problems, which are technically self-inflicted. Was deceived into trying to kill his best friend in his update, but has apparently since calmed back down and made up. Has a lot more depth to his character than you might expect at first glance. Has personal issues with Merasmus the wizard. Is this the Soldier or the Demoman?
The RED and BLU Teams in general are also Not So Different. To the point that they're both identical aside from the colours of their tops (and team–painted cosmetics).
In The Suffering, Horace compares himself to the protagonist Torque in several scenes, though he often encourages him against becoming too much like him:
You had a wife, right? Didja love her? How far would you go to make sure she stayed yours? When you get mad, you feel you could kill a man, rip him apart with your bare hands. You ever feel that way? Maybe you're not like me, it's hard to say. Ya gotta fight it. Don't let this place do to you what it did to me.
In Grand Theft Auto IV, Niko is driven for revenge against the guy who sold out him and his friends for $1,000. When he finally confronts the guy, Darko Brevic, he is asked how much he charges to kill someone. It seems that Niko knows that Darko is right as it shows in his choices: if he pulls the trigger on the guy, he feels empty and unsettled; if he doesn't and lets Darko go, Niko still feels angry but also a little bit better at the same time, since Darko is in a very, very sorry state and will continue to live on in suffering.
Darko also resembles Niko very much physically. Pretty unsettling...
The Lost MC and the rest of society also have more in common than one might expect, even though the Lost claim to be more about independence and freedom. For a one-percent biker gang, the Lost seem to have an awful lot of protocol: bikers have to ride in a strict formation, they can only call for certain degrees of firefight support if they're the President, and so on. This is even discussed in the opening cutscene of "Off Route," when Johnny is asked if fighting "The Man" has made him any happier. Johnny's response?
Johnny: "There's always a man. He just wears a different uniform."
In V, should you decide to kill Trevor, Michael will start ranting, attempting to justifying Trevor's death. Michael starts acting a little unhinged during the rant. Not So Different indeed.
In Fallout 3, if you confront the murdering, inbred, cannibalistic residents of the town of Andale about their unsavory habits, their leader demands to know how many people you've killed. And throws 'judge not lest ye be judged' in your face, to boot.
In Legacy of Kain: Soul Reaver, the final battle includes Raziel confronting Kain about raising his vampire lieutenants from the corpses of prominent Sarafan (vampire hunters):
Raziel: The Sarafan were saviours, defending Nosgoth from the corruption that we represent! My eyes are open, Kain... I find no nobility in the unlife you rudely forced on my unwilling corpse! Kain: You may have uncovered your past, but you know nothing of it. You think the Sarafan were noble? Altruistic? (laughs) Oh, don't be simple. Their agenda was the same as ours!
This is shown to be true in the ending of Soul Reaver 2, when it proves that the Sarafan were controlled by Moebius, The Dragon of the series, and thus are bigoted and self-righteous. Raziel and his past, human self share this dialogue:
Human Raziel: You're a righteous fiend, aren't you?
Raziel: We both know what you truly are. You're no better than the vampires you so despise. A voracious parasite, masking its hunger within shrouds of righteousness!
In Warcraft 3, Mannoroth taunts Grom Hellscream, saying that they are the same. Grom responds by screaming defiance and charging forward to kill him.
In the World of Warcraft quest chain required to forge Shadowmourne, the Lich King includes this argument in his Break Them by Talking to you as you steal the souls of your fallen Scourge enemies. Darion Mograine, however, challenges you to kill without being consumed by its power.
In a Duskwood quest, when you learn that Stalvan Mistmantle killed his studentand her lover when his feelings for her were not reciprocated, his brother Tobias is horrified at this and confronts the now undead Stalvan, who confirms this. Stalvan then suggests that Tobias is feeling what he did- enough rage to kill someone- and Tobias transforms into a Worgen and fights him alongside the player. After Stalvan is defeated, Tobias has a My God, What Have I Done? moment, but when you turn in the quest, he's calmed down and has concluded that it's up to him whether he truly becomes a monster.
The Wolfheart novel has this in spades, particularly with respect to the contempt King Varian Wrynn of Stormwind has for the Worgen, specifically for Lord Genn Greymane. Slightly subverted in that Varian doesn't particularly have anything against the Worgen in general, but the only ones he know are those from Gilneas, who he feels abandoned The Alliance in its hour of need. Malfurion is the one who tries to persuade both kings (mostly Varian) that they are not so different: both care about their respective people, both want to help the Alliance. Of course, the biggest similarity turns out to be the fact that Varian is revealed to be carrying the spirit of the wolf demigod Goldrinn whom the Worgen revere. After both kings reconcile, Varian leads the Worgen in a charge that breaks The Horde's advance into Night Elf lands and sends the orcs running.
In a non-villain example, in Deus Ex, Paul Denton mentions to the player the irony of how in order to defeat the one-worlders, the resistance forces, who support sovereignty and independence for the different peoples throughout the world, have to become a global organization.
It's never discussed, but in Deus Ex: Human Revolution Jensen can slaughter his way through the TYM manufacturing and R&D facilities, re-enacting the brutal raid by TYM-associated augmented commandos on Sarif Industries from the prologue.
When Arakune and Hakumen meet in the Arcade mode of BlazBlue, the latter tells the former that they are quite similar down inside.
In Teach Me, Ms. Litchi!, Litchi notes that "[Kokonoe and Taokaka]'re more alike than they seem. There's only a thin line between genius and... Tao."
Shockingly (and many seem to forget), Kokonoe is dangerously Not So Different with Terumi, the very individual she hated herself. Both of them are not 100% human, and in the same time look down on them. They also placed themselves so highly in priority and damninsufferable in it, so the majority of Kokonoe's would-be Well-Intentioned Extremist acts end up failing because she's only thinking of her own desires, such as the nukes she stored, she doesn't care if she'll have to take the whole civilization and humans in it so long as Terumi is dead by her own hands, the humans can die for all she cares, the same thing as Terumi only thinks of how he can have his fun of making people around him suffer or hate him.
Siblings Ragna & Jin also are also not so different from each other. At first glance, they look like your standard hot-headed protagonist and cool-headed rival archetypes, but as the series continues and they both go through their respective character arcs, it becomes increasingly clear that they're both kindhearted people who want to protect what's close to them, even if their attitudes don't always make this fact obvious. There's still some bad blood between them despite this fact though.
Jin also has this dynamic with Kagura. They're both tall, physically attractive, snarky and immensely Badass heads of powerful noble families in the Duodecim. It's suggested by characters in story that if Jin were never born, Kagura would've been the Hero of Ikaruga. They even both have a thing for motorcycles! The main difference between them, however, is personality: Kagura is a laid-back Nice Guy, Jin is an arrogant Jerkass.
In Dirge of Cerberus when Vincent impales Azul the Cerulean on his own cannon by hurling it through his torso, Azul comments that Vincent, possessed by Chaos, is an even more of a beast than he is.
Garland from Dissidia: Final Fantasy tells the Warrior of Light that they are both pawns in the endless cycle of battle. The warrior however argues that Garland is a man who's given in to despair, whereas he has not.
Lightning and Fang in Final Fantasy XIII have a 'not so different' moment, and the Datalog entry actually uses the phrase.
By the end of Mass Effect 2, Shepard and the Reapers are Not So Different. In the first game, Shepard and Sovereign are equally dismissive of the other. Shepard doesn't believe Sovereign is really "alive" — it's just a machine that can be broken. Sovereign considers organic life to be an insignificant aberration in the universe. When the second game begins, Shepard is revived and rebuilt with cybernetic implants to repair his/her skeleton, skin reconstruction, and synthetic fluids to restart his/her organs and blood flow. Then in the endgame it's revealed that Reapers are also cyborgs, in a way. New Reapers are created by pumping the liquefied organic material of millions into a mechanical Reaper superstructure. The new Reaper's form is based on the species used to create it. The partially grown Reaper encountered in the end is a Human Reaper, which makes it even more eerily similar to Shepard.
In the DLC, Lair of the Shadow Broker, the Spectre Tela Vasir, in her dying breath, will call Shepard out for condemning her for being a Shadow Broker hitman, when Shepard works for the terrorist organization Cerberus. She'll even point out that Cerberus did experiments on Sole Survivor Shepard's own squad.
Shepard and the Illusive Man are not so different; depending on certain decisions, Shepard is perfectly willing to let innocent people die to achieve his/her goals, and in The Arrival DLC the player has no choice but to sacrifice 300,000 innocent people to slow down the Reapers' invasion of the Milky Way. Couple this with the "Bring Down The Sky" DLC from the first game, where Balak asks "Who's the real terrorist here?" if you decide to capture him at the expense of the hostages he'd taken, and the conclusion of Arrival is a lot more depressing.
There's also Nassana Dantius, an amoral asari politician who's been targeted by Thane Krios for assassination. To secure her building, she hired dozens of Eclipse mercenaries and, when things got desperate, ordered the many salarian construction workers captured or killed, resulting in a massacre of unarmed workers who posed no threat. When Shepard finally makes it to Dantius' office, the asari bitterly claims that the Commander has killed countless people and is no better than her. A Paragon dialogue option from Shepard can refute this by telling Dantius that she kills people because she thinks they are beneath her, whereas Shepard kills people who give him/her no choice.
Saren and Shepard, though it doesn't become fully apparent until the end of the third game - and he died in the first. Saren advocated a partnership with the Reapers in order to spare organic life, and even becomes an organic/synthetic hybrid, with "the strengths of both, the weaknesses of neither," at the end of the first game. Shepard becomes one too when they are resurrected at the beginning of the second game, using similar tech. And then, at the end of the third, one ending resembles what he advocated - Synthesis, giving organics synthetic aspects and synthetics organic understanding, making all life into cyborgs of one degree or another. The strengths of both, the weaknesses of neither.
Han'Gerrel, despite being an "ally", pulls this on you as well. At the end of the Geth Dreadnought mission, he starts firing on it the moment its barriers go down, even though your team is still on board; when you get back, whether or not you punch him in the stomach, he tells you that if the world being reclaimed in this battle was Earth, you'd be right on board with a little friendly fire. In the Destroy ending, he's right - you're willing to sacrifice, at the very least, your friend EDI, and possibly the entire geth culture if you ensured their survival, to take out the Reapers. You may even have sacrificed the geth and another friend, Legion, to preserve the quarians.
You'll get this at times in Iji if you kill too many enemies throughout the game. After all, Iji's trying to stop her species from being wiped out by unexpected alien threats. By the time Iji has a bodycount in the triple digits, those tasked with stopping her have exactly the same goal.
Big Bad Eve in Parasite Eve claims that Aya, the main character, is no different from her and that over time, her powers will help her evolve and grow stronger just like her. She also mixes this up with a few We Can Rule Together speeches, but Aya isn't buying any of it.
This is one of the main points in the plot of Tales of Symphonia. The hero of the game, Lloyd Irving, is outright compared to the Big Bad Mithos more than once. Mithos' final words drive the point home too. "Farewell, my shadow, you who stand at the end of the path I chose not to follow. I wanted my own world, so I don't regret my choice. I would make the same choice all over again. I will continue to choose this path!" It really makes you think on how close Lloyd would have come to being like Mithos if Colette had actually become Martel's vessel in the end.
Also in the same game, Zelos and Colette, while they're both considered protagonists, are often compared to each other due them both having status as Chosen, but are considered to be quite different from each other: Colette is a cheery if clumsy girl who always tries to help other people and look on the positive side of things, while Zelos is a loudmouthed, perverted cynic who isn't afraid to be blunt. However if you really look at their situations you see that they both try to hide their pains and insecurities beneath their smiles and pretend like nothing's wrong, which in both cases lead to negative consequences.
Between members of The Party in Tears to Tiara 2. When discussing the prospects of an alliance with Qart Hadast, Monomachus calls them cowards for abandoning their previous alliance as soon as the war turned against Hispania, and Hanno not a real friend and family because he just sat back and watched Hasdrubal die. Enneads reminds him that they, loyal subordinates, also sat back and watched him die.
The main plot of NieR loves this trope too. Particularly when you find out that the Shadow Lord you've been hunting, the one who "kidnapped" Nier's daughter/sister (depending on the game version) Yonah, turns out to be the "real" Nier. The character you've been playing the whole game? Just a construct made to house the real Nier's soul. And both of them have the same goal - saving their daughter/sister Yonah from the one trying to take her away, no matter what.
In Radiant Historia, Stocke realizes that he likely would have turned out like Heiss if he had not found friends to give him hope in the future.
Malefor: Such determination to get here. It seems we share other qualities besides our color.
The Elder Scrolls V: Skyrim has a very subtle one when the player is talking to Paarthurnax, a dragon who has overcome his inherent nature to kill and conquer and destroy through thousands of years of meditation and self control. He points out that all dragons have an inherent desire to be essentially destructive bastards - and then comments that you, the player, being Dragonborn and thus possessing the soul of a dragon, likely have the same urges to kill and steal and destroy, just like all the dragons you've been killing along the way.
From the same game, there's also the songs "Age of Aggression" and "Age of Oppression", sung by bards in pro-Imperial or pro-Stormcloak holds, respectively. The song tunes are identical and both songs have parts where the lyrics are the same.
In Asura's Wrath, Augus claims this is true with him and Asura during the fight against him. Defied by Asura, they couldn't be more different since Asura is actually fighting for someone he loves rather than for its own sake and that is what gives him the strength to defeat Augus in the end.
In Star Wars Bounty Hunter, when Jango Fett and his arch-nemesis Montross face down for the final time, Montross says "We are the same, you and I." Fett replies, hilariously, "Now you're justbeing mean."
Big Bad Natla in the Anniversary edition of Tomb Raider pulls this trope on Lara Croft during the final boss fight. She tries to mess with Lara's mind saying how Lara is obsessive and selfish like she is and that trying to save the world is just an attempt to redeem herself and that in reality, her heart is as black as Natla's. Lara doesn't fall for it and proceeds to kick her ass.
During Nigel West Dickens's missions in Red Dead Redemption, John Marston frequently grouses about the Snake Oil Salesman and how he cheats people out of their money. Dickens never hesitates to point out that Marston robbed people of their money at gunpoint, and refuses to let Marston get away with his fumbling Robin Hood defense.
Pulled on Max Payne by himself in usual Self Deprecatiing style in the third game, where he considers how the Cracha Preto are gunmen on a payroll and wonders if that's all he is.
DmC: Devil May Cry: Ultimately, both Mundus and Vergil see humans as subjects to be ruled. Dante even points this out: when Vergil expresses his desire to rule humanity, Dante responds "...you mean, like Mundus."
Sigma Star Saga uses a Meaningful Name to signify the similarity between your CO, Commander Tierney and the Krill leader, the Tyrannical Overlord. Both are willing to sacrifice their own homeworlds to get control of the bioweapon.
In BioShock Infinite, self-proclaimed prophet Zachary Comstock is considered not so different from Daisy Fitzroy or Booker DeWitt. All three of them are brutally dedicated to achieving their goals, whatever lies they have to tell or means they have to resort to. The reason for that is Comstock is an alternate-reality version of DeWitt that went through the baptism that DeWitt himself rejected.
The first Bioshock also features the conflict between Fontaine and Ryan; they both use very similar methods and functionally there isn't any difference between their various facilities.
There's also one between the first and second games; Lamb and Ryan, despite having polar opposite ideologies, both are willing to sacrifice their underlings to achieve their goals.
In Warframe, this is one of the things Alad V says of you if you support the Corpus during the Gravidus Dilemma.
In [PROTOTYPE], Alex Mercer displays intense distaste for Blackwatch and Gentek, especially the real Alex Mercer. He's ruthlessly violent and unfettered in trying to kill his way through them, not unlike Blackwatch's own willingness to stop at nothing. He also is determined to stop Elizabeth Green from triggering a Zombie Apocalypse. Come [PROTOTYPE 2], and he fully intends to follow in her footsteps and even restarts the outbreak in Penn Station, like the original Mercer did.
A version involving NPCs happens during one dialogue in RuneScape, where two of the pacifistic cave goblins, who are descended from a tribe of normal Always Chaotic Evil goblins who fled underground to avoid being forced to fight, are discussing what colour to change the city guards' armour to, the discussion echoes the plot line of an entire quest where two goblin generals are disagreeing over their tribe's armour colour.
A rare heroic example comes from Xenoblade - the protagonist, Shulk, rather than giving into Zanza's goading and killing Egil, instead decides to give him a speech about how alike each of them are, pursuing revenge for the loved ones they'd lost, and refusing to let Egil fall prey to his rage. Itworks.
From the Sonic the Hedgehog series, there is nowhere this trope is more present in than in the titular character and Shadow the Hedgehog. Shadow was unique among Sonic's rivals in that he was very similar to Sonic himself, excluding Metal Sonic who was an artificial construction deliberately designed after Sonic's image. Shadow is somewhat impatient and has quite the high opinion of himself, and is one of the few characters who can keep up with Sonic's speed. Although they do differ in that Shadow is way more serious and introspective than Sonic. This was actually a point of conflict for the two in Sonic Adventure 2 (Shadow's debut) where Shadow incidentally frames Sonic for a crime due to their similarities; they then spend the rest of the game trying to one-up each other accusing the other of being a "faker."
Pagan Min: But then I realized, I was only using Lakshmana's death as an excuse to do whatever I wanted to do. Just as you use those ashes to do whatever you want to do. God damn if it isn't fun.
Lampshaded quite well in Star Control II by the Druuge when you're going to fight them to obtain the formerly Utwig-guarded Precursor bomb
Druuge Captain: (...) We know your soul, young Captain. It is no brighter than ours! We acknowledge our greed. We revel in it. You are the dishonest one! Hiding your shame in shadows, you fabricate justifications, rationales! In the end, we are just the same. (...)
In Wolfenstein: The New Order, optional rebel character J has a less than rosy view of American society before Those Wacky Nazis took over with their Diesel Punk, pointing out that the Nazi's actions are just the logical extreme of views on racial superiority and purity that were held by virtually every country in the 1930s, and that in particular America used to treat colored individuals like himself almost as bad as the Nazis treated Jews. To the point that, as a black man, the Nazi regime is pretty much a case of Here Comes The New Boss. Player character B.J. Blascowicz, an American-born Polish Jew (who ironically looks like he stepped off of a Nazi propaganda poster about the Ubermench), doesn't take the comparison very well.
Undertale employs the trope between monsters and humans. You're told that monsters and humans fought in a war long ago with the humans being the victors, thus one would assume the monsters were evil. You quickly find out that the monsters have a culture very similar to humans (use of the internet, celebrating Christmas, etc) and should you spare monsters instead of killing them, they can see that not all humans are bad and the two sides might be more similar than they think.
On the flip side, Flowey the Flower tries to push you into accepting his philosophy, "In this world, it's KILL or BE KILLED" and, should you kill him at the end of the neutral path, his last words are a triumphant "I KNEW YOU HAD IT IN YOU." Conversely, if you choose to show him mercy, despite everything that he has done and is threatening to do should you let him live, he'll have a Villainous Breakdown and run away. Fleeing is one of the options in the "mercy" menu, meaning you've made him accept your philosophy, that kill or be killed are never the only options.
In a more meta sense, at the end of a Genocide playthrough, Flowey tells you his story. He has the power to SAVE and RESET just like you, and just like you he used it to find out every possible outcome, without regard for the fact that all the characters are people with feelings. He befriended everyone, then reset and killed everyone. If you're reading that speech, you most likely did the same thing. Or you're watching someone else play, in which case...
Flowey:At least we're better than those sickos who stand around and WATCH it happen...
Flowey:Those pathetic people who want to see it, but are too weak to do it themselves.
Flowey:I bet someone like that's watching right now, aren't they...?
Minecraft: Story Mode: Magnus and Ellegaard, despite their dislike of each other, are both stubbornly proud of their achievements and difficult to get on the good side of. When they meet the Wither Storm, they both come to the same conclusions (the one you recruited realizes it's a threat they could never have imagined and decides to go at night, the one not recruited wants to wait til morning, and if you pick going out at night, the opposing party says that they're only going because you're a fan of the other).