History Main / BecameTheirOwnAntithesis

* Story wise, Moira MacTaggert went from a human who was helping the mutants because it was the right thing to do to an anti mutant villain who was helping Orchis.

** [[Characters/MCULokiLaufeyson Loki]] attempted to murder all Jotunns and take over the Earth, craved the Asgardian throne and power granted by the Tesseract, tried to kill [[Characters/MCUThorOdinson Thor]] twice, [[NeverMyFault refused to admit he did anything wrong]], rejected Odin as his father, and [[KnowWhenToFoldEm gave in to the Avengers when he realized he was losing]]. The same person [[spoiler: helped rescue the citizens of Asgard from [[Characters/MCUHela Hela]], stopped caring about the Asgardian throne, tossed the Tesseract aside as if it was nothing, tried to save Thor thrice, publicly apologized for past misdeeds in a play he wrote, proudly called himself Odinson, and attacked [[Characters/MCUThanos Thanos]] knowing that he hardly stood a chance]].

* ''ComicBook/Batman'':

* ''ComicBook/BatmanVampire'': By the final book, ''Crimson Mist'', Batman has succumbed to his vampire nature, going from a noble hero and a ''major'' practitioner of ThouShaltNotKill to a monster who eagerly kills his RoguesGallery for their blood. Gordon even acknowledges it, citing it to Alfred as proof that [[ThatManIsDead the Batman they knew is gone]].
* Regular Batman stories deal with this trope when Batman is faced with a much deadlier enemy, usually the Joker, whose very existence is proving to be too chaotic. Batman refuses to cross any lines out of fear of becoming this trope, knowing that his crusade will effectively go up in smoke the moment he takes a life.

** [[Characters/MCULoki Loki]] attempted to murder all Jotunns and take over the Earth, craved the Asgardian throne and power granted by the Tesseract, tried to kill [[Characters/MCUThorOdinson Thor]] twice, [[NeverMyFault refused to admit he did anything wrong]], rejected Odin as his father, and [[KnowWhenToFoldEm gave in to the Avengers when he realized he was losing]]. The same person [[spoiler: helped rescue the citizens of Asgard from [[Characters/MCUHela Hela]], stopped caring about the Asgardian throne, tossed the Tesseract aside as if it was nothing, tried to save Thor thrice, publicly apologized for past misdeeds in a play he wrote, proudly called himself Odinson, and attacked [[Characters/MCUThanos Thanos]] knowing that he hardly stood a chance]].

* ''Film/SpiderManTrilogy'': Peter Parker, the awkward but cute and relatively devoted suitor and hero from the [[Film/SpiderMan1 first]] [[Film/SpiderMan2 two]] parts of the trilogy, briefly becomes a confident and manipulative egotist after bonding with an evil symbiote in ''Film/SpiderMan3''.

* ''VideoGame/MetalGearSolidVThePhantomPain'': In ''[[VideoGame/MetalGearSolidPeaceWalker Peace Walker]]'', Huey Emmerich courageously defied his boss, refusing to work for a deluded megalomaniac who thought he could do no wrong, and survived an attempt on his life in the process. In ''The Phantom Pain'', [[spoiler: Huey's become the deluded megalomaniac, abandoning his wife to die when she tries to defy him. All the courage and integrity he showed in ''Peace Walker'' is gone by the time of ''The Phantom Pain'']].

* In the end of ''Anime/CodeGeass'' Suzaku dons the mask and identity of Zero, the revolutionary leader he had spent most of the show trying to stop.

** Light Yagami of ''Manga/DeathNote'' is an interesting example that plays the reverse. He starts out as an apathetic and bored teenager who is prone to temptation and purpose. When he gains the Death Note, he becomes a petty, egotistical, manipulative, vindictive, lying murderer with [[AGodAmI a God complex]] who believes MurderIsTheBestSolution, including eventually planning to apply it to [[FelonyMisdemeanor the lazy and unproductive!]] However, when he has to surrender the Death Note as part of a long XanatosGambit and thus lose his memories, he becomes an honorable, highly empathic, idealistic teen [[RousseauWasRight who believes in the inherent goodness of man]] though with a greater sense of maturity before he got the Death Note.

* ''Anime/DragonBallZ'': Gohan falls into this during the Cell Games. Compare Gohan before he unlocks Super Saiyan 2 and after. Before [=SS2=] - a humble, soft-hearted MartialPacifist who makes it clear on more than one occasion that he doesn't like to hurt people, not even truly evil monsters like Cell. After [=SS2=] - an arrogant, borderline {{sadist}}ic, {{revenge}}-driven SmugSuper who eagerly beats Cell within an inch of his life and even deliberately prolongs the CurbStompBattle [[RevengeBeforeReason just because he wanted Cell to suffer as much as possible before he died]]. Thankfully, he breaks out of it, but only after his actions backfire horribly, resulting in his father's death.