History Main / BigBadSlippage

* In ''Literature/ATaleOfTwoCities'', Madame De'farge becomes this. Where in the beginning of the novel the first conversations with her present her as an ordinary woman, albeit with some relatively extremist views, when the revolution takes hold and France is thrown into chaos, she eventually becomes a strong leader in the revolution and is among the front runners in the category of "sending everyone with a shiny hat to their deaths."

** "Apparently" being the operative word." She is eventually saved and her sanity restored (though not by the main heroes.) However, it's clear that even now, "Eve" is not the Juliette of old. What she ''is'' is an awesome and terrifying HorrifyingHero. She has a ThatManIsDead reaction to her past as Juliette, but does still care about Nick enough to give Adalind an IfYouEverDoAnythingToHurtHer type warning.

* In book 3 of ''WesternAnimation/InfinityTrain'', Simon is the deuteragonist until the end of episode 5, when his refusal to redeem himself from the Apex's ways ultimately leads him to become the season's antagonist.

* [[JerkAss Eric Sparrow]] in ''VideoGame/TonyHawksUnderground'' starts off as the PlayerCharacter's best friend, and while Eric is a dumbass, he's not malevolent yet. Gradually over the course of the game, he gets worse and worse, screwing over the PlayerCharacter in increasingly worse ways until he finally becomes the BigBad and FinalBoss.

* ''ComicBook/TheTransformersLostLight'' does this with the character of Getaway. At first, Getaway seems to be just another member of the Lost Light's crew, engaging in all the wacky hijinks. Then he is disgruntled with the way the quest the ship is supposed to be on keeping getting interrupted and hates the idea that former Megalomaniacal Dictator Megatron is now a repentant member of the crew, then he starts plotting mutinies, wiping people's memories, putting people in a coma to trap them in memory loops so they keep repeating the same sequence of events over and over in their minds, making deals with serial killers, and tossing people into the robot piranha pit for the crime getting in his way or spoiling his plans. Not to forget, declaring himself as the next Future Prime of Cybertron and monologuing about his destiny.

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%% This trope is represented in the Pantheon/TropePantheons by Hal "Tighten" Stewart of ''WesternAnimation/{{Megamind}}'', in the Hall of Pantheon/AlignmentChanges.
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* In ''WesternAnimation/TheLegendOfKorra'', there is Kuvira, who starts out as a harmless background character in season 3 who helps save Korra's father in the finale. However come the final season, she is put in charge of stabilizing the Earth Kingdom after the assassination of the queen, and her fascist methods of unifying the country put her at odds with the main characters.
* ''WesternAnimation/SheRaAndThePrincessesOfPower'': Catra starts out as Adora's friend and general AntiVillain, but her severe InferioritySuperiorityComplex drives her mad as she gets constantly one-upped by She-Ra and abused by their step-mother Shadow Weaver. Eventually, Shadow Weaver ''defects'', convincing Catra that the forces of evil would rather redeem themselves than admit Catra was worth something, which causes her to ''snap'' and try to use a superweapon that goes out of control and kills some very important people, leaving Adora devastated and utterly vengeful against Catra.[[note]]Ironically, this put her in the ''best'' position to protect her people, as she had enough street cred from her super-villainy to convince Horde Prime to not destroy the giant superweapon (which happened to be the planet itself), or worse, accidentally activate it.[[/note]]

* In the backstory of ''ComicBook/{{Runaways}}'', Tristan and Lillie were superheroes back in the early 1900s, but a gang war changed their lives forever and left Tristan horribly disfigured. They spent the next century scheming to develop TimeTravel and undo the damage. Of course, what they [[GenreBlind fail to realize]] is that [[YouAlreadyChangedThePast when they send the Runaways back in time to bring their younger selves into the present day in order to let them escape the gang war]], they just perpetuate a StableTimeLoop in which the Runaways themselves ''spark the gang war''.

* [[JerkAss Eric Sparrow]] in ''VideoGame/TonyHawksUnderground'' starts off as the PlayerCharacter's best friend, and while Eric is a dumbass, he's not malevolent yet. Gradually over the course of the game, he gets worse and worse, screwing over the PlayerCharacter in increasingly worse ways until he finally just becomes the BigBad and FinalBoss.

* ''VideoGame/TheGreatGaias'': Virgil Mythos starts as a party member and seems to value his friendship with Pots, but it's later revealed that Pots's murder of his family caused him to develop a lust for power and revenge. When he enrolls in Sorbithia, he's upset at how he feels the Circle of Twelve is limiting him and he eventually falls for Zacharael's temptation to become his apprentice. Eventually, his ambition causes him to betray Zacharael and use the Hourgem of Valnyr for himself, leading to him learning the Singularity spell from Khargynoth. He then uses Singularity to fuse with Zacharael and Adramelech, and then [[TheStarscream feigns loyalty to Maultor. In the normal ending, Virgil succeeds in absorbing a weakened Maultor and manages to unseal himself 1000 years into the future, usurping Maultor/Malviticus's role as BigBad.]]

* ''Literature/TheCollector'' Fredrick Clegg starts off as a lonely young man who kidnaps a young girl called Miranda whom he has a crush on. As an UnreliableNarrator, he manages us to convince us that he cares for Miranda and that she's just being ungrateful and mean to him. Come the second part of the novel which shows Miranda's perspective and reveals that he's a VillainProtagonist who has abducted her and expected him to kill or rape her and has developed StockholmSyndrome as a result of his treatment. Thinking that giving him sex is what he wants and that he'll let her go afterwards, Miranda seduces Fredrick out of desperation, causing his misogyny and abusive behaviour to reveal itself post-sex. He then forces her to be a subject of degrading photos and eventually causes her to die of pneumonia due to neglecting to take her to a doctor. By the end of the novel, he finds her journal and finds out that he hated her, convincing him to cancel his plans to kill himself and moves onto a new victim which is similar in appearance. At this point, all Fredrick Clegg has learnt is that he was too lenient with Miranda and must become a stricter captor, now eager to put his newfound knowledge to use.

* In ''VideoGame/FireEmblemFates: Conquest'', one of the main antagonists is Takumi, your younger brother on the Hoshido side. He's easily the most RecurringBoss of the Hoshido siblings, fought as many as five times compared to elder siblings Ryoma and Hinoka, tied with three if you count the battle at the start of the route split. Each time, he only gets more and more violently enraged with you and the other [[FantasticRacism Nohrian Scum]]'s general existence and "betrayal," acting more antagonistic overall than anyone else in Hoshido, even returning from his presumed suicide and acting as the FinalBoss of the route even after you've defeated [[DiscOneFinalBoss King Garon and his cronies. This is partially the result of the influence of the GreaterScopeVillain, though he was only able to do this so extensively due to Takumi's own anger being unchecked.]]