History Main / JumpingOffTheSlipperySlope

Compare with BaitTheDog, MoralEventHorizon, MotiveDecay, {{Aesoptinum}}, and HeWhoFightsMonsters. Can be a result of a WellIntentionedExtremist realizing that there is NoPlaceForMeThere and becoming a full-time villain. Frequently accompanied by ThenLetMeBeEvil. In case the characters in question were friends prior to Slope-Slipping, it probably triggers WeUsedToBeFriends. If the slippery slope has been greased with AppliedPhlebotinum, that's TheDarkSide.

* When ''Film/TheBatman2022'' gets on the trail of a mysterious serial killer of the city's officials who calls himself ''Riddler'', [[spoiler: and the revelations of the supposed victims crimes are enough to make Batman second-guess himself, it appears that this will be the case with the Riddler and that he slowly loses contact with reality over who is to blame for the state of the city when he puts civilian lives in danger with an out-of-control-car and attempts to murder Bruce with a bomb for his father's crimes. It then turns out subverted as the final part of his plan doesn't so much come to light but proves to have been there all along: flooding Gotham City and gunning down the survivors, leaving no doubt that he sees every single person in the city as just as guilty as the sell-outs and the mafia and will not tell them apart.]]

* When ''Film/TheBatman2022'' gets on the trail of a mysterious serial killer of corrupt officials with an agenda who calls himself ''Riddler'', and the revelations of the supposed victims crimes are enough to make Batman second-guess himself, ut appears that this will be the case with the Riddler and that he slowly loses contact with reality over who is to blame for the state of the city when he puts civilian lives in danger with an out-of-control-car and attempts to murder Bruce with a bomb for his father's crimes. It then turns out subverted as the final step of his plan comes to the light as being part of the first step-murder: flooding Gotham City and gunning down the survivors, making the mass murder of innocent just as much a part of the plan as the vigilante killing of the sell-outs.

A form of DebateAndSwitch, because they never ''really'' address the question of whether the original ambiguous action was acceptable or not. As such, this trope is sometimes a sign that the creator is biased in favor of the less morally ambiguous answer to a conflict, but realized part-way through that the alternative they are trying to argue against [[StrawmanHasAPoint makes more sense than they intended to present it as]]. Also helps to [[StatusQuoIsGod maintain the status quo]] by ensuring the main characters never question their own morality too closely, thus keeping the more simpler BlackAndWhiteMorality from [[GrayingMorality degrading]] into GreyAndGrayMorality. Compare SlowlySlippingIntoEvil for a longer, more developed process of going from "ambiguous" to "evil". Compare FaceHeelTurn for when it is a morally good character who turns evil.

** Yoda warns of the danger of TheDarkSide, giving a slippery slope argument on how it works: "Fear leads to anger, anger leads to hate, and hate... leads to suffering." However, it is exceedingly rare for somebody to not simply go to hate and Dark Side in the EU.
** Anakin Skywalker from the prequels. Specifically, note how quickly he goes from [[spoiler:agonizing over his role in Mace Windu's death]] to [[spoiler:killing younglings without a problem]]. Anakin finally slips so far that his own wife, Padmé Amidala, loses the will to live and eventually dies, and Obi-Wan Kenobi is forced to duel him, which ends gruesomely. In order to keep Anakin alive, Emperor Palpatine -- a.k.a. Darth Sidious -- subjects him to painful body reconstruction. The final push to the Dark Side comes from Palpatine himself: when Anakin asks if Padmé is still alive, the Emperor tells him that, in his anger, he killed her. In pure disbelief of this, Anakin's true power flares up, and he screams out in despair, fully overtaken with pain and hate, completing his transformation into Darth Vader. What was especially loathsome of him was that, rather than desiring everyone's well-being, his honest desire for good was corrupted into infatuation and affection (he wanted to be together with her, alive, rather than desiring what's best for everyone); a desire to be with her for the sake of his pride; to feel good about himself for being able to keep the people he knows personally from dying (although, sadly for him, Palpatine never had any concern for his wife, to begin with).

* Amanda Young in the ''Franchise/{{Saw}}'' series makes Jigsaw look downright merciful by the [[Film/SawIII third movie]]. Of course, this was the fault of Jigsaw himself, who made her another murderer in an attempt to "help her", much to his shame when he realizes this. It didn't help that Jigsaw's other major apprentice in the first seven films, Mark Hoffman, was already far down the slope too, tugging on Amanda's leg at the time.

* Amanda Young in the ''Franchise/{{Saw}}'' series makes Jigsaw look downright merciful by the [[Film/SawIII third movie]]. Of course, this was the fault of Jigsaw himself, who made her another murderer in an attempt to "help her", much to his shame when he realizes this. It didn't help that Jigsaw's second apprentice by order of the time they were revealed, Mark Hoffman, was already far down the slope too, tugging on Amanda's leg at the time.

!!Example Subpages:

!!Other Examples:

* The character of [[spoiler:Amanda Young]] in the ''Franchise/{{Saw}}'' series makes Jigsaw look downright merciful by the [[Film/SawIII third movie]]. Of course, this was the fault of Jigsaw himself, who made her a murderer in an attempt to "help her", much to his shame when he realizes this. It didn't help any that [[spoiler: Jigsaw's other protégé, Mark Hoffman, was already far down the slope, tugging on her leg at the time]].

* ''Anime/DragonBallSuper'': Zamasu, a Supreme Kai of [[AlternateUniverse Universe 10]], is first introduced as being [[FantasticRacism distrustful of mortals]] and of gods for allowing mortals to live. From his introduction, he's SlowlySlippingIntoEvil... and he finally jumps off the slope when he learns of the Super Dragon Balls and the power he could gain from them, which spirals into him breaking into Zuno's temple and outright threatening his life in order to get information about them. From there, rather than simply wait a year for the Super Dragon Balls to be active again, he decides to [[spoiler: kill his master Gowasu and steal his Potaras so he can use his [[TimeTravel Time Ring]], jump ahead a year, wish for Goku's body, and begin his quest to wipe out all mortals, but not before killing all the gods knowing they would do everything to stop him]]. Zamasu freely admits that what he's doing is evil, but it's [[KnightTemplar all to serve a greater good]]. At the same time, [[spoiler: Future Zamasu deserves special mention. When Goku Black murders Gawasu, he is at first horrified and rushes to his master's side. After some words from Goku Black, he immediately joins his side and helps him murder all the other gods in the universes before going on to wipe out mortals]].

A form of DebateAndSwitch, because they never ''really'' address the question of whether the original ambiguous action was acceptable or not. Also helps to [[StatusQuoIsGod maintain the status quo]] by ensuring the main characters never question their own morality too closely, thus keeping the more simpler BlackAndWhiteMorality from [[GrayingMorality degrading]] into GreyAndGrayMorality, as well as prevent a potential case of StrawmanHasAPoint. Compare SlowlySlippingIntoEvil for a longer, more developed process of going from "ambiguous" to "evil". Compare FaceHeelTurn for when it is a morally good character who turns evil.

->''"All it takes is one bad day to reduce the sanest man alive to lunacy. That's how far the world is from where I am. Just one bad day."''
-->-- '''The Joker''', ''ComicBook/TheKillingJoke''

* ''Fanfic/IWillNotBow'' series: Noboru starts out as a DirtyCoward who abandons Alice and Mai to save his own skin, but he's not exactly evil at first. Come ''Blazing Revolution'', [[spoiler:he, out of jealousy that Alice chose Ren over him, throws all moral concerns out the window, making a doctored video involving a fight with Laughing Coffin in an attempt to frame Kirito and Ren for murder, and outright assaulting Alice in real life while forcing her to grovel before him to prevent him from posting another video to completely ruin their reputation.]]

* Fanfic/SummerDaysAndEveningFlames: Sergeant Sherry's logic for [[spoiler: starting a gang war]] is sound, in a twisted sense, as it eliminated all the major players in the Farrington crime circuit. However, she somersaults off the ledge when [[spoiler: she's about to be arrested for the indirect murder of dozens of city guards, where she shows little remorse and violently escapes. Sherry made a perfect landing when she pulls all of her connections to get Iron removed from his post and threatens him and his family if he pursues her]].
* ''Fanfic/MassEffectHumanRevolution'''s version of Toombs. It was one thing when he was hunting the Illuminati scientists who conducted unethical experiments on him, but he lost any moral high ground when he started taking hostages with intent to kill in order to force out into the open the one who rescued the final scientist.
* In the ''Fanfic/TheDresdenFillies'' story ''False Masks'', the plot is that the Order Triune, an ancient society have mistaken Harry Dresden to be their ancient foe, resurrected after 1200 years, and try to kill him. They attempt to poison him, and then kidnap the ponies close to him, like Twilight. When their coverts efforts fail, they take a direct approach.[[spoiler: Summon '''HE WHO WALKS BEHIND''' (''TWICE'') to kill him, ignoring all the ponies around him that could have also died. And when that fails, they were ready go through the Mane 6 and the princesses to kill him and would have done so, [[KarmicDeath had they not been sacrificed themselves to summon a demon.]] And it turns out that Obsidian ''never'' was resurrected, so they had committed all these crimes for nothing.]]

* Sasuke in ''[[http://ficwad.com/story/213011 Eroninja]]'' goes from "Kill my brother to avenge my clan" to "Kill the ones who "made" my brother kill my clan"[[note]]In this story, Itachi wasn't blackmailed or threatened into killing his clan; he came up with the idea himself[[/note]] to "destroy the current shinobi system and kill people close to Naruto because it'll hurt him". Notably, Sakura gives up on Sasuke much sooner than Naruto but everyone (Naruto included) consider Sasuke past the MoralEventHorizon when he tries to kill his own mother.
* ''Fanfic/BeAllMySins'' has Natalie, a sweet innocent girl thrust into the grim darkness of the [[TabletopGame/Warhammer40000 41st Millennium.]] She immediately offers her devotion to Slaanesh in order to live, then has to undertake a human sacrifice to prove her commitment, and from there it's pretty much a head-first dive into drugs, cannibalism, dark rituals and murder.
* ''Fanfic/HarrysMadness'': Harry Potter goes insane in Fifth Year and begins murdering all his real and perceived enemies, turning the DA into his dark legions of global conquest.

* ''Fanfic/ArrowRebirth'': Felicity Smoak did a lot of morally ambiguous and outright selfish things in the previous timeline, but the former were almost always for good causes so her loved ones were more willing to ignore the latter. [[spoiler:Then she plots to murder Laurel ([[UnknownRival who doesn't even know her in this timeline]]) just to get Oliver back, chucking out any idea of moral ambiguity out the window and cementing her as a villain. When Oliver finds out what she was up to after she died, he's genuinely shocked, and it makes him wonder if he ever really knew her in the first place]].

* ''Anime/DragonBallSuper'': Zamasu, a Supreme Kai of [[AlternateUniverse Universe 10]], is first introduced as being [[FantasticRacism distrustful of mortals]]. From his introduction, he's SlowlySlippingIntoEvil... and he finally jumps off the slope when he learns of the Super Dragon Balls and the power he could gain from them, which spirals into him breaking into Zuno's temple and outright threatening his life in order to get information about them. From there, rather than simply wait a year for the Super Dragon Balls to be active again, he decides to [[spoiler: kill his master Gowasu and steal his Potaras so he can use his [[TimeTravel Time Ring]], jump ahead a year, wish for Goku's body, and begin his quest to wipe out all mortals]]. Zamasu freely admits that what he's doing is evil, but it's [[KnightTemplar all to serve a greater good]]. At the same time, [[spoiler: Future Zamasu deserves special mention. When Goku Black murders Gawasu, he is at first horrified and rushes to his master's side. After some words from Goku Black, he immediately joins his side and helps him murder all the other gods in the universes before going on to wipe out mortals]].

* In the ''LetsPlay/DreamSMP'' roleplay, Dream could, at least initially, be argued to be a WellIntentionedExtremist who believes he's doing the right thing. However, over the course of the SMP, his methods become more and more extreme, with Season 2 being the jumping-off point as he [[spoiler:[[WouldHurtAChild abuses Tommy]] to the point of attempted suicide, destroys L'Manberg permanently by having it [[NukeEm nuked to bedrock]], commissions the construction of a [[TheAlcatraz nigh-inescapable]] HellholePrison to hold dissenters from [[ControlFreak his rule]], and plans to kill Tubbo and imprison Tommy in the aforementioned prison]].

* {{ComicBook/Mystique}} falls of the slippery slope after the death of her partner, Destiny. She hesitates for a while about crossing the line of killing the autistic minor, {{ComicBook/Legion}}, for revenge but quickly chooses to ignore her moral qualms and attempts to finish him off anyway. After this, she continues to spiral downwards into the more sociopath nature she is known for today.
* It's arguable how far down the slope he already was, but the arc ''Franchise/{{Superman}}: Ending Battle'' is this for NinetiesAntiHero Manchester Black. Initially, Black managed to just hover on the line between UnscrupulousHero and NominalHero, but, after he learns Superman's secret identity, he leaps across the MoralEventHorizon; telepathically takes control of the supervillains (literally, all the supervillains) to attack anyone who's ever had any contact with Clark Kent, mind rapes the rest of the Elite (the only people who give a damn about him), and finally tortures and [[spoiler:pretends to]] kill Lois Lane, all as part of a massive ThanatosGambit to destroy Superman by goading him into breaking the [[ThouShaltNotKill One Rule]] [[spoiler:pointlessly]]. When Superman refuses, Black suffers a major HeelRealization and [[DrivenToSuicide telekinetically blows his own brains out]].
* ''Franchise/GreenLantern'': Hal Jordan, who got so pissed off that the Guardians forbid him to use his ring to temporarily recreate Coast City that he flew to Oa, maiming numerous other Green Lanterns in the way and stealing their rings, leaving them for dead in space, killed Kilowog, killed Sinestro, absorbed the whole power of the main battery (destroying it in the process), became the villain Parallax and then [[strike:tried to destroy the universe in order to recreate it "the right way"]] actually, successfully destroyed the universe, but then the heroes hijacked his attempt to recreate it to make an acceptably similar replacement. In ''ComicBook/GreenLanternRebirth'' it was retconned as he being [[DemonicPossession possessed by the fear entity Parallax]].
* Notably averted by Alan Grant's [[Franchise/TheDCU DC Universe]] character of ComicBook/{{Anarky}}: where originally the character was scripted to be willing to murder in pursuance of his anarchic philosophy, as written he upholds the same moral standards as Franchise/{{Batman}}, which makes for some nice NotSoDifferentRemark interactions.
* In Franchise/{{Superman}} Annual 3 in the ''ComicBook/{{Armageddon 2001}}'' crossover, Superman declared war on all nuclear weapons. At first, he just took away all nuclear weapons. Then, he started to steal from rich countries to give to the poor countries. Over the course of ten years, he became more intense and actually started sinking submarines that has nuclear weapons on them. When people started to die (accidentally), everyone started to get worried that Superman has gone too far. So, Batman decided that he had to kill Superman with the kryptonite ring.

* Dealt with in a two-issue arc of ''ComicBook/NewXMenAcademyX'' involving Prodigy, a student at the Xavier Institute with the ability to absorb the knowledge of anyone in the immediate vicinity, but ''only'' as long as they're in the immediate vicinity. When ComicBook/EmmaFrost discovers that he's subconsciously put a block in his mind that prevents him from retaining the knowledge permanently, David asks Emma to remove the block, figuring he'll be able to do so much good for the world that way. The story then fast-forwards a few months, and David is already head of his own MegaCorp that has developed cures for cancer and AIDS. How did he achieve this breakthrough? [[spoiler:He killed his friend, the healer Elixir, and harvested his organs]]. Okay, that's certainly bad, but we're still at the point where it can be argued to be worth it. The next issue fast-forwards again, to twenty years later, and David is now the President and has united most of the world's countries into a utopian OneWorldGovernment. And he's also [[spoiler:planning the genocide of the Chinese because they refused to join]]. Okay, ''now'' he has to die. Fortunately [[spoiler:the whole thing turns out to be an illusion, courtesy of Dani Moonstar, in an effort to convince him to leave the block in]].
** Another X-Men example in one of ComicBook/{{X 23}}'s creators, Dr. Xander Rice: He forces Dr. Kinney to carry Laura's fetus to term by refusing to allow her to search for another host (so it's do it, or let the embryo die), shoves the girl into a radiation chamber at the age of ''seven'' to forcibly jump-start her healing factor by nearly killing her with radiation poisoning (when it's implied he could have gotten the same results with a "safer" dosage. Or just allowed her to manifest naturally), ''denies'' her anasthesia when he surgically removes her claws several days later to coat them in adamantium, uses ColdBloodedTorture to condition her to the trigger scent, puts her in the "care" of an AxCrazy psychopath, treats her as an animal and subjects her to years of physical and emotional abuse, tries to kill her at one point by abandoning her on a mission, and oh yeah, sends her [[spoiler: to kill the man who practically raised him from a toddler, and the man's wife and son (who is actually ''his'' son from an affair with the woman)]]. Rice doesn't so much as jumping off the slippery slope as taking to it in a rocket sled. And then keep on going.
*** Laura herself at times teeters at the brink of it. Her willingness to kill and otherwise get her hands dirty puts her at odds with her teammates (when she teamed up with Hellion to rescue Cessily from the Facility he was greatly disturbed by how far she was willing to go as part of the mission, including outright torture and murder of the people they interrogated), and she's constantly struggling with her training; ''ComicBook/AvengersArena'' reveals she automatically formulates multiple plans to kill ''everyone in a room with her'' the moment she steps inside. [[FridgeHorror Even her friends and loved ones]], and she ''can't shut it off''. [[IronWoobie It's astonishing that for all the pain, suffering and heartbreak she's endured she manages to keep holding on to her humanity.]]
* [[ComicBook/{{Azrael}} Jean-Paul Valley's]] tenure as Franchise/{{Batman}} was exactly this. When given the mantle of the bat by the injured Bruce Wayne, he started out simple and was willing to follow rules. However, after the Scarecrow doused him with Fear Gas and [[BrainwashedAndCrazy the System]] kicked in, Jean-Paul's morality started to waver. He came close to viciously murdering villains such as ComicBook/TheJoker, Tally Man, and Mr. Freeze, and nearly killed Tim when he tried to get Az!Bats to tone down the violence. After letting Abbatoir die by falling into a vat of molten steel, which ensured his captive's death, he decided to embrace his more vicious and brutal side once and for all, leading Bruce to come back and take the mantle from him by force. It's implied [[DependingOnTheWriter by some stories]] that Bruce's fear of going down that same path is why he adheres so rigidly to [[ThouShaltNotKill never killing villains]], no matter how evil they are and no matter how likely they are to escape and kill again.
* In the ComicBook/{{Chick Tract|s}} [[http://www.chick.com/reading/tracts/1033/1033_01.asp "Fairy Tales,"]] a young boy named Harry has a shocking revelation that ''immediately'' causes him to go on a violent rampage and become a [[AxCrazy mass murderer]], ultimately winding up next to Osama Bin Laden on the FBI's most wanted list. What was this world-shattering revelation, you ask? He realized that there's no reason for morality when he was told that... [[spoiler:Santa Claus, the Easter Bunny, and the Tooth Fairy aren't real]]!
* ''ComicBook/AstroCity'' has [[spoiler:El Hombre,]] a former superhero who fell from grace after he became a HeroismAddict and tried to use EngineeredHeroics to refresh his glory. [[spoiler:He eventually masterminds a plan to slaughter ''hundreds'' of super-villains all so he could take the credit and make a name for himself once more.]]
* Both ''ComicBook/IronMan2020Event'' and its lead-up details this for Arno Stark, who has [[TakeALeverInJerkass taken a level in jerkass]] by having Tony declared illegitimate and taking away his very identity, taking rather draconian actions to prevent an event, and eve replacing other humans with robots. [[spoiler:It's all for naught as his disease has come back and he's suffering from SanitySlippage, the "Extinction Entity" merely being a delusion.]]

* ''WesternAnimation/AvatarTheLastAirbender'':
** Jet's goal is to protect children like himself orphaned by the warmongering Fire Nation and to fight back. However, it's made pretty clear that Jet has jumped off this slope when he attempts to [[spoiler:drown an entire town uninvolved with the war effort, murder innocent elderly people, and put his own life at risk for the purpose of revenge]]. He notably later attempts to jump back ''on'' the slope, but it [[RedemptionEqualsDeath doesn't turn out too well]].
** It's implied he had already fallen that far long before they met him- the plan was already in place and he had apparently been attacking travelers indiscriminate to their threat-level for a while now. Not to mention his "enforcers" thought nothing of Jet ordering them to kill Sokka. It's not entirely clear whether he truly regretted his actions for being ''morally wrong''.
** This is what leads to [[spoiler:Zuko's eventual HeelFaceTurn. He'd been hesitating for a while, thinking that his family really were good people, despite all the massive evidence otherwise: it's when his father and sister plan to burn an entire country to the ground that he realizes they've jumped off]].
* ''WesternAnimation/TheLegendOfKorra'':
** Tarrlok starts out as a jerkass and [[ManipulativeBastard manipulative]] SleazyPolitician. Then he goes completely off the deep end by [[spoiler:imposing a curfew on all non-benders and arresting anyone who complains or even has connections with Equalists. He arrests Korra's friends to blackmail her to join him and when she refuses, attacks her and reveals himself to be a bloodbender. By the end of the episode, he's got her locked in the back of a Satomobile to take her somewhere she'll never be found]].
** Amon and the Equalists start off with a relatively valid complaint: Benders really do have all of the power in Republic City. Up until Episode 10, they had only committed a really extreme crime. Then, they jump fully on off the slope by [[spoiler:launching a full-scale invasion of Republic City, complete with ''bombings and gas attacks!'']]. Arguably, their point is also undermined by [[spoiler:the fact that Amon is actually a stupid-powerful waterbender himself and uses his own bloodbending ability to destroy others' ability to bend]], but whether that's this trope or simple {{Hypocrisy}} is open for debate.
** Kuvira starts off Book 4 a WellIntentionedExtremist with valid reasons for reuniting the Earth Kingdom under her own rule. She uses some questionable means to persuade cities to side with her, but given the incompetence of the heir to the Earth Kingdom's throne, people didn't fault her for [[spoiler:refusing to relinquish her power to him]] as had been previously agreed, because she seemed much more capable of actually leading. [[spoiler:Attacking the United Republic]] might have been going a little far, but a lot of fans could still sympathize with her point of view, given that it used to be Earth Kingdom territory. Then, when her fiance is [[spoiler:captured and she is offered a deal that will basically allow her to take Bataar Jr. and go home as the uncontested ruler of the Earth Empire if she only agrees to leave the United Republic alone, she decides it would be a better idea to launch an attack with the spirit cannon that will kill her fiance because she believes it will kill Korra as well]]. The show makes a point out of the fact that Bataar Jr. is not okay with sacrificing his life for the cause.

* ''WesternAnimation/DarkwingDuck'' has this happen with the most likable villain of the show Dr. Bushroot in his origin episode. He starts off by being [[ManslaughterProvocation driven to murder]] the people who bullied him, made him lose his job ForTheEvulz and mocked him after his mutation. Then he deteriorates morally by seeking revenge against the Dean who cut his funding and then against Darkwing and Launchpad for stopping the attempted murder and by the end he tries to mutate the girl that he liked against her will so that he could have company. Good Lord!
** If Bushroot's descent was bad, the fall of Jim Starling for Darkwing's rebooted counterpart in ''WesternAnimation/DuckTales2017'' makes that one look tame by comparison. Starling used to be an actor who played a ShowWithinAShow version of Darkwing, which was cancelled in part because [[WordOfGod of his own egotism]], leaving him with menial work and an unsalvageable career for years. Then, when he learns the series is being rebooted as a gritty movie, he gets so incensed that he's not reprising his role that he tries to sabotage the production, culminating in a battle between him and his replacement on a burning movie set. It's thanks to an impassioned speech from Launchpad that makes him realize he's gone too far, but in saving the pilot from an exploding pylon does Starling seemingly perish...[[spoiler: only for that one act to drive him to think his replacement [[NeverMyFault sabotaged him]], driving him to become NEGADUCK]].
* Played for laughs in the ''WesternAnimation/{{Futurama}}'' episode "Anthology of Interest", where Leela asks for a WhatIf scenario with the premise of "what if I were more impulsive?" The first real sign of her newfound attitude (aside from buying new boots that are identical to her old ones but with a green stripe) is killing Farnsworth [[InheritanceMurder because he's left her a large inheritance.]] This then escalates to her killing Hermes after he learns she did it, and then killing Bender when he learns and tries extorting her. After having killed three people, she realizes that [[MurderIsTheBestSolution she's been solving far too many problems with murder lately]], and tries to calm down... and then proceeds to murder Amy for insulting her looks.

!!Examples:

[[folder:Live-Action TV]]
* ''Series/TwentyFour'' does so respectively with Tony Almeida and Jack Bauer in its final two seasons. In Tony's case, [[spoiler: After his wife and unborn son were killed, he sets out to kill the mastermind in any way possible. But tactics he employs in trying to do so include things like murdering the director of the FBI, nearly exposing several innocent people to a lethal pathogen, and attempting to sacrifice Jack in order to get close to his target]]. As for Jack, after years of being tortured, screwed over, and having friends and loved ones taken from him, he finally loses it when [[spoiler: Renee Walker is killed as part of the Russian's cover-up and the President betrays him by refusing to reveal the truth since exposing them would also expose their involvement in the murder of a foreign president, which in turn would ruin the chances of a peace treaty she's trying to have signed. Jack claims that he'll take justice into his own hands and expose the truth, but his doing so involves murdering TheMole solely because had been working with the Russians beforehand ''long before'' there was any movement made to kill Renee, slaughtering several members of the Russian government, ''opening fire on a crowd of innocent people'' (which although it was mainly to disable random pedestrian cars, it's still made perfectly clear that Jack could have easily killed someone with even the slightest slip-up and really didn't give a damn at all) and attempting to assassinate both Yuri Survarov and Charles Logan even though killing the both of them would be guaranteed to start a war between the USA and Russia that would likely lead to the deaths of millions]]. The series does its best to make sure that what he's doing isn't in ''any'' sort of heroic light.
* ''Series/The100'': At the start of season two, Finn Collins, who started the series as TheConscience, begins to slip as a result of trauma from the end of the first season and [[LoveMakesYouCrazy desperation to rescue his friends and love interest, Clarke]], from presumed Grounder captivity. At one point, he executes a captured Grounder after his group interrogates him, justifying it by saying that the Grounder would've revealed their location. His companions, however, are shocked by his ruthlessness. Later, he ends up attacking an innocent Grounder village and rounding up its inhabitants for interrogation. After one of the villagers startles him, he shoots them dead, then continues firing into the unarmed, frightened crowd, killing 18. Even [[AxCrazy known murderer Murphy]] is shocked by this atrocity, and the show itself doesn't let him get away with it. Finn initially tries to [[IDidWhatIHadToDo defend himself]], but eventually turns himself in to the Grounders. Clarke [[MercyKill mercy]] [[KillTheOnesYouLove kills]] him after she learns the Grounders plan to torture him to death for his crimes.
* Season 2 of ''Series/AgentsOfSHIELD'' had an interesting ethical dilemma set up between S.H.I.E.L.D., who felt that people with superhuman abilities needed to be indexed and monitored to protect regular people from them in case they ever became dangerous, and the Inhumans, who felt their rights were being taken away and such policies would inevitably lead to wide-scale imprisonment or extermination. Any question of who had the moral high ground went out the window when Jiaying, the Inhumans' leader who had been corrupted by a brutal vivisection at the hands of Dr Whitehall, a member of HYDRA, murdered a S.H.I.E.L.D. representative in cold blood at a peace meeting and framed it to look like S.H.I.E.L.D. was attacking them, then set up a trap to draw as many S.H.I.E.L.D. agents as she could to an aircraft carrier she had hijacked and planned to flood with synthesized Terrigen Mist, which would kill any non-Inhumans who were exposed to it. Her power, previously assumed to be longevity through a HealingFactor, was suddenly revealed to require her to literally drain the life out of other people to sustain herself (granted, she originally hated this power until her vivisection), which she attempts on ''her own daughter'' (who also happens to be an Inhuman) after she [[CallingTheOldManOut calls her out]] on the above plan and tries to stop her.
* ''Series/{{Angel}}'': During Season 3, Wesley translates a prophecy reading "The Father Will Kill The Son". Not quite sure how to handle the situation, he [[spoiler: takes the baby away - for good - and even strikes Lorne unconscious when he finds out what's going on. To make that even worse, Wesley gets his throat cut and the baby taken away from him. And it was a false prophecy, anyway. Now Holtz has the child and takes him with him into a Hell Dimension, raising him to hate Angel]].
* ''Series/{{Battlestar Galactica|2003}}'': Given that ''the entire cast'' has been through hell backwards by the end of the pilot miniseries and it just goes FromBadToWorse after that, this trope is kind of understandable...
** The "Pegasus" arc has been accused of this by some critics, with Admiral Cain taking about twenty minutes to go from merely being a hard-assed martinet to ordering the rape of a pregnant woman as a JackBauerInterrogationTechnique and sentencing the crewmen who interfered to summary execution. In fact, the episode "Pegasus" had had to be radically trimmed to fit network time constraints; some of the footage that was lost (and reinstated on the DVD) implied the passing of more time than seems to go by in the episode as aired. The ''Razor'' movie, which came later, also expanded on her backstory; she was already a little unbalanced even before the fall of the Twelve Colonies, at which point something... ''[[DespairEventHorizon broke]]'', thus retconning the events of "Pegasus" into more of a VillainousBreakdown.
** There's also the episode where the woman put in charge of a tribunal takes about 24 hours to go completely nuts with power, and attempt to accuse the commanding officer who appointed her of the crime she's investigating.
** Similarly, in "Black Market", the leader of the organisation running it does a pretty good job of defending the need for a BlackMarket in the fleet. Then he talks about having child prostitutes, so [[spoiler: Lee can shoot him without feeling guilty]]. Lee did acknowledge the argument about the need for a black market, though, given that he allows it to stay in business afterwards. He just wanted them to clearly understand where the MoralEventHorizon was.
* ''Series/BuffyTheVampireSlayer'':
** In Season 6, Willow goes from [[spoiler: killing Warren]] as revenge for [[spoiler: Tara]] to trying to [[spoiler: kill]] the uninvolved other guys [[spoiler: from the Trio]]. Then to hurting [[spoiler: Buffy, Anya (who initially sympathized with her), and Giles]] and finally to trying to [[spoiler: end the world]]. All within a couple of episodes which together take place within less than one day.
** The Initiative in season four was clearly using questionable methods in their study of demons, vampires, and other paranormal activities, but they were getting the job done and had effectively defanged Spike, one of history's most dangerous vampires. Then they decided that Buffy was a liability and tried to kill her. When it seemed like they were getting back on the slope, they took to torturing Oz (a good werewolf rather than an evil demon) and tried to kill the Slayer again.
** Faith. When she first showed up, she had a lot of problems, not the least of which was that she enjoyed slaying a little too much, but she was definitely a [[AntiHero good guy]]. [[spoiler: Then she accidentally killed a man and the guilt (combined with all the speeches made to her about why she should be feeling guilty) made her snap and go NUTS.]] Later on this happens even more when she gets yelled at for her actions (such as when she tried to kill Angel or saves Buffy and an evil slayer).
** Warren originally created a robot that would obey his every whim, but he eventually abandoned the android because he wanted a girlfriend that would be a partner in the relationship and he fell in love with a woman with her own ideas and personality. His creation of a SexBot and then abandoning it to "die" raises plenty of questions about his character, but he ultimately decides that he wants a woman that he can respect and interact with. In his later appearances in Season 6, he is a misogynistic bastard who tries to brainwash, and eventually kills, his ex-girlfriend because she would not submit to his desires.
* ''Series/{{Charmed|1998}}'' has a twist on this in Season 2's "Morality Bites"; after the sisters use their powers to pull a vengeful yet relatively harmless prank on a man who continually lets his dog defecate on their driveway, Phoebe has a premonition of being burned at the stake for killing someone with her powers a decade in the future. One adventure later, they are sent back to that point in time to prevent falling prey to this trope, worded well by Phoebe:
-->'''Phoebe''': Once you break the small rules, it's just a matter of time before the big ones are next.
* An episode of ''Series/TheCommish'' features a VigilanteMan who initially only humiliates bad guys who deserve it. But when an accused rapist/murderer is found not guilty (for good reason), the vigilante (who believes he got OffOnATechnicality) clubs him to death, setting the team on his case.
* Seems to happen about once a season in ''Series/DoctorWho''. A few notable examples;
** In [[Recap/DoctorWhoS8E2TheMindOFEvil "The Mind of Evil"]], a scientist invents a machine that removes criminal impulses from the human mind, and offers it to the government as a means of dealing with dangerous criminals without resorting to the death penalty. Turns out its inventor is actually the Master and the device brainwashes people to serve him.
** In [[Recap/DoctorWhoS12E4GenesisOfTheDaleks "Genesis of the Daleks"]], Davros invents the Dalek (or "Mark III Travel Machine", as he initially calls it) ostensibly for the purpose of making life easier for mutated Kaleds. When his superiors start getting cold feet about the research, he has the entire Kaled race wiped out.
*** The audio drama ''Davros'', released much later, showed that Davros was already lying in a heap at the bottom of the slope by this point. Not hard, when you're the leading [[MadScientist scientist]] of a race of [[ANaziByAnyOtherName ersatz Nazis]]...
** The original Daleks in [[Recap/DoctorWhoS1E2TheDaleks "The Daleks"]] do this too. They're paranoid and threatening, but as the result of a nuclear war with another race that devastated their country and turned them into mutants incapable of surviving outside of travel machines in a specially-built environment with metal floors. While they trick the humans into it, all they really want is anti-radiation drugs which would allow them to leave their suits. It then turns out that their bodies have adapted to need radiation and the withdrawal sends them mad before killing them, so they decide to shoot out a load of radioactive waste onto the planet again when they realise they can't survive without radiation.
** In [[Recap/DoctorWhoS27E3TheUnquietDead "The Unquiet Dead"]], gaseous beings called [[OurGhostsAreDifferent the Gelth]] need to [[PuppeteerParasite animate human corpses]] to house themselves and hence survive — creepy, if not evil. [[GenocideDilemma They ask to come]] to Victorian Cardiff, and the Doctor, dismissing the {{Squick}} of his companions, agrees. After the Gelth come through, however, it turns out [[ILied they lied]] about their numbers and intentions. They want to take over all of Earth's ''living'' bodies — but even before we learn this, we can tell that they're malevolent, because shortly after getting the Doctor's go-ahead, they [[GoodColorsEvilColors switch from pale blue to bright red and Satanic]]. Apparently, they were "demonic" all along, see?
** In [[Recap/DoctorWhoS28E5RiseOfTheCybermen "Rise of the Cybermen"]], when the British government refuses to fund John Lumic's Cyberman research, he kills the leadership and begins forcibly cyber-converting the British population.
** [[Recap/DoctorWhoS30E1PartnersInCrime "Partners in Crime"]] begins with an alien conspiracy that... helps people lose weight effortlessly by giving them pills that cause one pound of fat to turn into an adorable little creature called an Adipose every night. While this comes off as slightly sinister, it's hard to see how they could ever be an enemy- until, of course, the "breeders" of the Adipose decide that their current method is too slow and try to make Adipose out of the entire body of their victims, killing them in the process. Jumping? More like a great, flying leap.
** It's implied in [[Recap/DoctorWho2006CSTheRunawayBride "The Runaway Bride"]] and more-or-less stated in [[Recap/DoctorWhoS30E13JourneysEnd "Journey's End"]] that the reason the Doctor travels around with a companion is so that he has someone to remind him not to do this, since he has so much power and gets into such intense and painful situations it would be hard for him not to slip, and hard for anyone to stop him once he starts sliding. The Doctor officially jumps in two stories in which he is without a companion, though he does manage to return to the side of right in both:
*** The Tenth Doctor does this in the last 10 or so minutes of [[Recap/DoctorWhoS30E16TheWatersOfMars "The Waters of Mars"]]. After having spent the whole episode with a group of people destined to die, the Doctor snaps and decides to save them after most of them have already been killed. Just moments after saving the remaining people (in the most epic way possible), the Doctor decides that he can mess with the timeline in any way he sees fit, completely ignoring his species' laws. At this point, the Doctor is almost antagonistic. Thankfully the Doctor is only in this state for one scene and is brought down a couple of pegs before he can really do anything.
*** The Twelfth Doctor does this in the Series 9 finale [[Recap/DoctorWhoS35E12HellBent "Hell Bent"]]. All season he'd been struggling with how much he could or couldn't do to save those around him — letting O'Donnell die and being willing to die himself but still trying to save his beloved companion Clara Oswald from a preordained death in [[Recap/DoctorWhoS35E4BeforeTheFlood "Before the Flood"]], and immortalizing Ashildr/Me in [[Recap/DoctorWhoS35E5TheGirlWhoDied "The Girl Who Died"]] because it was the only way he could save her from the grave. In [[Recap/DoctorWhoS35E10FaceTheRaven "Face the Raven"]], he considered going on a RoaringRampageOfRevenge that would have slaughtered innocents over [[spoiler:Clara's ''actual'' death]] but Clara talked him down. But he spent the next episode, [[Recap/DoctorWhoS35E11HeavenSent "Heaven Sent"]], not only imprisoned and completely alone but subjected to ColdBloodedTorture. So in "Hell Bent", which takes place after he escapes, he is effectively insane and once again tries to alter a fixed point in time by [[spoiler:undoing Clara's death altogether]], which took place ''billions'' of years ago in-universe by the time he manages to get the means to do so; he has no plan to avert the destruction of the universe this would cause and basically hopes he'll get lucky, and justifies his actions by invoking his "duty of care" and DudeWheresMyReward For bonus points, he also intends to [[spoiler:MindRape Clara of her memories of him]]. But [[spoiler:Clara herself]] manages to talk him down, and he returns to his best self by not only giving up his TragicDream but [[spoiler:losing his memories of her]], which means he no longer is consumed by the horrors that drove him to extremes.
* In the final season of ''Series/{{Elementary}}'', Odin Reichenbach is initially presented as a WellIntentionedExtremist -- he kills people, but only "bad people" and he sincerely believes he's saving innocent lives by doing so. Then, when Sherlock tries to show him another way, by rehabilitating one of the potential killers he's identified, he murders innocent people and frames the guy rather than admit he's wrong.
* ''Series/{{Fringe}}'': Walternate originally just wanted to save his universe, even if it meant destroying a parallel universe and its inhabitants. Then he attempted to [[spoiler: kill his son and the mother of his grandchild]].
* ''Series/GameOfThrones'':
** Theon condones the murder of two innocent boys to make it appear as though he has executed the Stark boys Bran and Rickon.
** Tyrion has clearly snapped by the end of his trial, but his murders of Tywin and Shae cement how far he's gone from the noble anti-hero he once was. Oddly he sort of climbs back up the slope in later seasons, trying to protect his brother and sister from Daenerys's wrath (unlike his book counterpart who is openly in favor of killing everyone in King's Landing and even demands to Daenerys that he be allowed to rape his sister Cersei).
** The most extreme case is [[spoiler:Daenerys just flat-out snapping in the final season and burning most of King's Landing to the ground, soldiers and civilians and even ''children'' alike, an act that flies completely in the face of all the principles she ever held or espoused]].
* There are few series with more examples than ''Series/{{Gotham}}''.
** The prime example that the whole series explores in his descent to murder and monstrosity is [[spoiler: Edward Nygma. He was in love with Kringle and demanded her abusive boyfriend's face to leave her alone. He responded by assaulting him, and in the ensuing conflict he ended up [[ManslaughterProvocation stabbing him to death in an extreme move of self-defense]]. Things went really downhill when Kringle found out and during a psychotic outburst of panic he strangled her to death without even realizing it. When he saw what he did, he lost any resemblance of a conscience and murdered a possible witness and then he did two atrocities in one strike by murdering an innocent cop in order to frame Jim for the latter's murder]].
** The Balloonman is one of the only examples who can make anyone question what is right and what is wrong and where do his actions belong. The whole point of his character was that he was tired of seeing big criminals getting away with ruining lives because they were part of the system and started targeting corrupt officials. Even Jim looks uncertain and confused about the moral questions that arise during their showdown. Too bad he chose to close the debate he was winning by [[spoiler: saying forget it and trying to shoot Jim despite knowing that Jim was a good cop.]]
** Even the much darker Jerome Valeska whose later acts [[MoralEventHorizon would need a page of their own]], says that his mother (and his first kill) horribly abused and mistreated him and evidence shows that he is likely telling for once the truth.
** By season 3 we get once more an almost textbook example with [[spoiler: infected Captain Barnes who starts with killing serial murderers who get pardoned despite the overwhelming evidence to what they did (once again) and ends up being a walking, talking BlackAndWhiteInsanity trope by himself once he tells Gordon that if he isn't with him, he is guilty too and tries to shoot him. And all this while rightfully pointing out that James did the same thing to Theo. Its an almost example, because he was infected and wasn't just being himself]]. It seems by now that Jim is one of the only who didn't go all the way over the edge.
* ''{{Series/Hannibal}}'': Will goes from doing some morally ambiguous, but still understandable things, (such as trying to have Hannibal killed) to something unambiguously evil in "Naka-Choko". It turns out to be a con to convince Hannibal that he'd gone slope-jumping, [[AmbiguousSituation which might not have been a con after all]]. [[AntiHero It's complicated at best]], mostly because Will's [[ArchEnemy feelings]] [[BirdsOfAFeather towards]] [[OneTrueLove Hannibal]] [[EvilTastesGood are]] [[LonelyTogether also]] [[LoveMakesYouEvil very]] [[ConflictingLoyalty complicated]].
* An episode of ''Series/{{MacGyver|1985}}'' involved a business owner attempting to have the Challengers Club shut down because one of its members stole a truck from his printing business. What could have been a two-sided conflict between a racist business owner - albeit one who had a legitimate axe to grind - and a teenager conditioned by poverty and racism to view white people as the enemy shifts step by step into a case of the boy being a clear-cut victim of The Man. First it turns out the business owner framed the kid for stealing the truck as a pretext to have the Challengers Club shut down. Then he escalates to murdering the club owner. Then it turns out he prints white supremacist propaganda and thinks "niggers should be drowned at birth".
* Lincoln Potter was the HeroAntagonist of Season 4 of ''Series/SonsOfAnarchy'', depicted as a largely well-intentioned but morally ambiguous CrusadingLawyer, with a [[ManipulativeBastard manipulative]] streak that occasionally shone through. When he reappears as the de-facto BigBad of ''Series/MayansMC'', he has become a cold, ruthless, FauxAffablyEvil authoritarian who will use any means, legal or illegal, to achieve his goals. He explains that coming within a hairs breadth of bringing down SAMCRO and the Gallindo Cartel, only to be forced to walk away at the last second due to [[spoiler:interference from the CIA, who want to keep Gallindo's gun and drug trade open for inscrutable foreign espionage purposes]], made him decide that there was no point trying to bring justice to the world or make things better, and instead he should just maintain the status quo in favour of the powerful.
%%* Several characters in the 1998 ''{{Series/Merlin|1998}}'' series, but most notably [[MurderTheHypotenuse Uther]] and [[GodSaveUsFromTheQueen Mab]].
* In the ''Series/{{Merlin|2008}}'' BBC series, Morgana was understandably angry and bitter, but nevertheless sympathetic. However, between seasons two and three, she transformed into a smirking villain.
* In one episode of ''Series/{{Monk}}'', when Captain's Stottlemeyer's wife is gravely injured in the fallout of a union assassination, Stottlemeyer proceeds to teeter dangerously close to the edge in his hunt for the sniper. [[spoiler:Near the end, he very nearly launches a raid on the suspected union until Monk manages to crack the case.]]
* Season two of ''Series/MurderOne'' featured a storyline about Clifford Banks, a serial killer who tracked down and executed criminals who escaped justice, or had an unsuitably short prison sentence. He started out on this path through the murder of his retarded brother, he never kills innocent people, and throughout the arc, a few people comment that "sometimes the streets need sweeping." Any moral ambiguity is then done away with by the lawyers finding out that Clifford actually killed his brother himself over his frustration about giving up his whole life to care for him, causing a mental breakdown that directed his guilt outwards onto other criminals.
* In the pilot episode of ''Series/TheShield'', Vic Mackey partakes in [[CowboyCop numerous dubious acts including the use of excessive force during arrests, working with a drug dealer and beating a suspect with a phone book in order to make him talk]][[note]]and the last one is at the behest of the new Captain of the precinct who has sworn to bring Mackey down, when the suspect is ''clearly'' guilty but refuses to say anything, and his victim is in mortal danger[[/note]], but other cops [[AntiHero justify his actions by stating that he gets tangible results]]. Then, at the end of the episode, he [[spoiler:shoots another police officer in the face to prevent him from gathering evidence against Vic's team]], firmly establishing him as a VillainProtagonist for the rest of the series.
* Holly in ''Series/SlingsAndArrows'' wants to streamline the Festival's business end and replace most of its Creator/WilliamShakespeare with musicals. This only marks her as a villain in the context of a show where Shakespeare is SeriousBusiness, until she starts abusing her boyfriend and deliberately aggravating the heart problem of a board member who disagrees with her.
* ''Series/{{Smallville}}'':
** The season 8 finale took an incredible amount of heat for various reasons, and one of them was this trope.
** Season 9 had [[TwoLinesNoWaiting multiple concurrent threads]] of [[WellIntentionedExtremist Well-Intentioned Extremism]] colliding into one big [[SelfFulfillingProphecy Self-Fulfilling prediction of doom]]:
*** Tess Mercer established an alliance with the Kandorians to [[GreenAesop save Earth]] from mankind's destructive ways but in the BadFuture, [[spoiler: she [[LesCollaborateurs collaborated]] fully with Zod's despotic rule over a dying human populace]].
*** Amanda Waller as the head of Checkmate employed threats, murders, and kidnappings to prepare for a coming [[ApocalypseHow war against the aforementioned Kandorians]]. Then she [[spoiler: casually ordered the execution of a group of [[BroughtDownToNormal non-powered Kandorians]],]] cementing her status as a {{Fantastic Racis|m}}t.
*** General Zod's interest in restoring his and his fellow Kandorians' powers (against Clark's objections) made sense in light of the repeated violent threats they faced from Amanda Waller and other humans ProperlyParanoid about aliens among them. [[spoiler: After Zod and the Kandorians get their powers restored, he destroys Checkmate, kills Faora (and their unborn child) for going against him, and plans to take over Earth with the Kandorians loyal to him and make it into a New Krypton.]]
* ''Series/StargateSG1'':
** Gerak in season 9. At least he got a [[RedemptionEqualsDeath redemptive death]], though.
** The Ori could stray into this. At first, it seems that, while their practices are primitive, their ultimate goals are noble enough, helping others to achieve ascension. Then it's revealed that this is all a lie, and the Ori are manipulating people's belief to gain more power.
** The rogue NID. At first, they're stealing alien technology with the purpose of using it to defend Earth, making them into {{Knight Templar}}s. Then it turns out they're just in it for the money.
* ''Franchise/StarTrek'':
** In ''Series/StarTrekVoyager'', it's revealed that after giving the Hirogen holographic technology from ''Voyager'', the Hirogen quickly got bored with the standard holograms and started creating more intelligent holograms to make their hunts better. These holograms eventually became self-aware and rebelled, before freeing others hologram in the area. Even ''Voyager's'' EMH joins their cause, agreeing that this is technically a form of slavery. Unfortunately, they quickly move onto anyone who uses humanoid holograms at all, regardless as to whether those holograms are actually ''sentient''. The Doctor is horrified when their leader brutally murders a man to free the holographic equivalent of ''Clippy''.
** Deliberately invoked by the writers of ''Series/StarTrekDeepSpaceNine'' in the case of Gul Dukat. Due to the charisma with which Marc Alaimo played the character, and his sometime-alliances with the main characters, a significant number of fans developed a DracoInLeatherPants effect, forgetting that Dukat had been a genocidal military dictator. To combat this in later seasons the writers had Dukat go mad, declare that he should have exterminated the entire Bajoran race, and finally become the series' equivalent of a Satan-worshipper.
** Invoked in-universe in the episode "For The Uniform", Sisko realises that Michae edington is essentially living out a heroic fantasy as leader of the Maquis, and has come to view Sisko as an InspectorJavert-esque AntiVillain consumed by his obsession with catching Eddington (which isn't completely inaccurate). Sisko starts acting like he's completely lost it and decided to indiscriminately bomb Maquis colonies, manipulating Eddington into surrendering by framing it as a HeroicSacrifice to stop his mad rampage.
* ''Series/{{Supernatural}}'':
** Season 2, "Bloodlust". The Winchester brothers met rogue vampire hunter Gordon Walker while looking for a nest of vampires. Gordon seems like a decent enough chap and a worthy ally, and Dean likes his "kill all the monsters and enjoy the hunt" philosophy. Dean and Sam end up fighting when Sam reveals that other hunters say Gordon is bad news. Before this can go any further, Gordon takes a swan dive off the slope when the local vampires turn out to actually be peaceful, having sworn off killing humans, yet he still attempts to slaughter them. Then he tries to feed Sam to the head vampire to prove she's still a monster, and attacks Dean when they try to protect her. Bad move.
** This is Castiel's entire character arc during Season 6. Desperate to defeat Raphael in the civil war in Heaven, Castiel begins performing many morally questionable acts, not the least of which is [[spoiler: allying with Crowley]], and rapidly skipping several shades of grey. This ultimately culminates in the season finale, where he [[spoiler:jumps right into VillainProtagonist territory when he absorbs all the souls of Purgatory and [[AGodAmI declares himself the new God]]]].
** Whilst on a smaller scale, [[spoiler: Castiel's ascension to God and later 'death']] causes Dean to take a much harsher stance on supernatural beings throughout Season 7, most apparent in 'The Girl Next Door'.
** Season 9 and Season 10 had this happen to Dean after he took on [[TheCorruption the Mark of Cain]], with him becoming more violent and prone to murderous rages in Season 9. He allows himself to be killed at the end of the S9 finale in fear of what he's becoming, but [[spoiler: the Mark wouldn't let him die, [[AndThenJohnWasAZombie thus reviving him as a Demon]], but he's cured and turned back into a human in the beginning of S10]]. The Mark, however, still remains, and he eventually relapses mid-Season 10, with [[spoiler: [[MoralityPet Charlie's]] death]] being the catalyst for him giving himself up fully to the Mark's influence. The Season 10 finale has him summon [[TheGrimReaper Death the Horsemen]] in an attempt to have the Mark removed permanently, only for Death to refuse, because removing the Mark without passing it on to someone else will [[spoiler: unleash [[PrimordialChaos the Darkness]], an entity that was locked inside the Mark of Cain since before creation, and is the reason the Mark corrupts anyone who bears it, thus making it the ultimate BigBad of the series, by proxy of being the original source of evil in ''Supernatural'']].
* ''Series/TeenWolf'': Lydia references this trope, warning Allison over the phone that Scott might fall off of it, starting with being thirty minutes late for dates and eventually ending up at domestic violence.
* ''Series/XenaWarriorPrincess'':
** Najara, a character who either converted or killed criminals. Rather quickly, Najara is revealed to be insane, and can't tell the difference between obvious criminals and lesser offenders.
** Calisto has a legitimate beef with Xena (Xena killed her family and wiped out her village), but every time she shows up she racks up more collateral damage and DisproportionateRetribution, becoming increasingly less sympathetic in the process. A later episode reveals that Calisto, who has time traveled to the day her parents died, is the one who killed her parents and left her younger self to die. Note that none of this reduces her hate for Xena, showing that she doesn't even care at this point.
[[/folder]]

[[folder:Video Games]]
* ''VideoGame/SpecOpsTheLine'': The ''entire game's events'' have been one long one for [[spoiler:Captain Martin Walker, with this game being about him becoming a VillainProtagonist. Starting out wanting to be a hero with a seemingly well-meaning goal of saving Dubai, he continues to make things worse for Dubai until he becomes its greatest threat; the "enemy soldiers" he's been killing throughout the game were soldiers trying to protect the surviving civilians, or civilians manipulated by government agents to act as the resistance. Walker's most infamous feats throughout the game are killing dozens of soldiers and civilians at a refugee camp with white phosphorus, and later helps destroy Dubai's water supply, and ultimately leads his own unit to their deaths. All the while he continues to blame Konrad so he can find some way to justify his deeds or ignore his conscience. When finally confronted by the hallucination of Konrad - a manifestation of his conscience - Walker has the choice to accept or deny responsibility for what he did, and can ultimately slaughter a squad of soldiers expressly trying to help him.]]
* ''VideoGame/GodOfWarI'': As shown [[VideoGame/GodOfWarChainsOfOlympus in]] [[VideoGame/GodOfWarGhostOfSparta the]] [[VideoGame/GodOfWarAscension prequels]], Kratos was always a SociopathicHero on his very best of days, but he was perfectly capable of compassion and feelings of camaraderie. But then his mistakes start to add up, he spends every waking second being pushed and prodded and tormented by the gods, he loses half the things he cared about to his own failings and the other half is taken away. As of [[VideoGame/GodOfWarII the second game]], he's devolved into a straight-up VillainProtagonist. The game opens up with him waging war alongside the Spartans in Rhodes, and after Zeus betrays him, the man just snaps. It's all downhill from there.
* ''VideoGame/InjusticeGodsAmongUs'' has a lot of this: Franchise/{{Superman}} doesn't just jump, he flies down the slope at Mach speed after being tricked into killing Lois and then killing Joker in retaliation, establishing a totalitarian dictatorship where in exchange of his "protection", everyone that even dares to protest his methods gets a swift death, as exemplified by what happened to that universe's ComicBook/GreenArrow [[spoiler:and later Shazam, and according to the backstory, Hawkman, causing Hawkgirl to retaliate in vengeance, only to be {{Brainwashed}} into servitude]]. He does it a second time when he goes from maintaining order with an iron fist -- and demonstrably creating a peaceful world at the expense of a few lives, and freedom of course -- to flattening cities himself because people don't agree. Via backstory, we see the only surviving ComicBook/TeenTitans being ComicBook/{{Cyborg}} and ComicBook/{{Raven}}; both end up disillusioned and Raven ends up giving in to Trigon's influence, gaining a lust for torture and becoming Trigon's worshipper instead of trying to prevent his coming. And while Damian Wayne [[spoiler:did accidentally kill Dick Grayson, he didn't look back in regret and goes far worse than before because Superman, being his 'new father figure', convinced him to continue his extremist ways]]. Meanwhile, Wonder Woman is unquestioningly convinced of Superman's "logic" for some reason, even after it gets clearly obvious she's doing the things he's supposed to be preventing.
* ''VideoGame/Portal2'''s [[spoiler: Wheatley]] does this as part of [[spoiler: his FaceHeelTurn]] after [[spoiler: a core transfer with [=GLaDOS=] gets him DrunkWithPower.]] He calls the escape lift to let Chell go, gushing over [[spoiler: how cool his new body is]], but when Chell is almost out, he starts laughing. The music turns dark, his laughter turns into a downright EvilLaugh, and the lift starts lowering again. He starts monologuing about how HE did all of this, and when [=GLaDOS=] points out that it was CHELL who did all the work, [[spoiler: Wheatley]] gets so mad, he [[spoiler: takes [=GLaDOS=] apart and [[DisproportionateRetribution sticks her in a potato battery]]]], showcasing that the [[spoiler: cute little personality core he'd been for the entire duration of the game has turned into a sadistic monster]].
* ''VideoGame/{{BioShock|1}}'':
** [[spoiler:Harvesting even one of the Little Sisters gives you the bad ending; it is simply implied that you jumped off the slope and became ADAM- and power-hungry the moment you first harvested]].
** Andrew Ryan. The whole point of Rapture was to create a utopia where individuality and free enterprise were unrestrained by the government. Once Fontaine began to rise in power though, paranoia and a fear of losing his city turned him into an iron-fisted, totalitarian dictator, [[HeWhoFightsMonsters the exact opposite of what he set out to become]].
* ''VideoGame/BioShock2'':
** If the player jumps off the slope [[spoiler: so does Eleanor.]]
** Sophia Lamb believes that humanity's root problem is that everyone is genetically predisposed to be self-serving, and happens to have taken over a city that has all but perfected genetic engineering. Does she work on developing a gene tonic that would cure the user of their selfishness? Nope, her plan is to turn the city into a hivemind, with her own daughter serving as its mother brain against her will.
* In ''VideoGame/NeverwinterNights'', Aribeth leaps quite quickly down the slippery slope (partially excused as Morag is messing with her brain and her intentions)
* Subverted in ''VideoGame/RondoOfSwords''. After a very harsh FriendOrIdolDecision that ends up on the favor of the Idol, Serdic experiences an immediate Karmic backlash, complete with [[DarkMessiah title change]], [[DiscardAndDraw power swap]], and [[EvilMakeover costume switch]] to reflect his [[ShootTheDog dog shooting]]. While his Nakama repeatedly [[WhatTheHellHero accuse or suspect him of jumping off the slope]], Serdic experiences no lapse in emotional or moral health. The epilogue also reveals that he was a just and well-loved ruler with a happy marriage.
* ''VideoGame/GrandTheftAuto''
** In ''VideoGame/GrandTheftAutoViceCity'', while it's debatable how moral Tommy Vercetti is, the mission "Messing with the Man" has him go around causing destruction in the city and killing innocent civilians just to prove to a biker gang that he is badass enough and gain their trust, and having no problem with it whatsoever.
** CJ and Niko Bellic from ''VideoGame/GrandTheftAutoSanAndreas'' and ''VideoGame/GrandTheftAutoIV'', respectively. Let's assume that they're good-hearted people at the start (if the cut-scenes are any indication), and let's assume the player doesn't do any killing not encouraged by the storyline (which is a stretch but go with it). Now watch how their lives unfold. CJ, in particular, goes from "I guess I'll kill this guy since he's been screwing with my gang" to "guess I'll just kill all these guys for no apparent reason" so quickly it might make you wonder if you're still playing as the same guy. By the end of the game, at least, he gets to see the awful results of his actions, and he tells his family outright in the final cutscene that they need to rein it in and be more subtle. It helps that he was being blackmailed for the entire game. His brother has fewer excuses, and the other Grove [=OGs=] have none.
*** Well, Niko may seem pretty nice at the beginning of the game, but the plot [[spoiler:eventually reveals that he is a war criminal out to kill other war criminals]]. So there's a good argument that he starts the game as a major bad guy, and indeed committed even more horrible acts before the game started than you can ever do in it.
* ''VideoGame/MegaManX8'' has [[spoiler:Lumine, a New Generation Reploid, and director of the Orbital Elevator project. ''He's the '''BigBad''''', '''not''' Sigma this time]]. It doesn't help that the whole of [[spoiler: Lumine]]'s tale plays on the game's subtitle, ''Paradise Lost''. [[spoiler: Lumine is the analog to Satan, rising against his creators and their vassals. He even seems to have enough truth in his words to shake up X into being completely unable to attack.]]
* It used to be that when the ''VideoGame/{{Warcraft}}'' series needed a new villain, Blizzard would seem to throw a dart at a character board and have the one they hit go insane.
** Kael'thas Sunstrider's goal was originally to improve his suffering people, and despite their re-branding as blood elves, they were a shining example of DarkIsNotEvil. Even when he allied with the [[SnakePeople naga]], and the [[WellIntentionedExtremist partially demonic Illidan]], it was a move of desperation and managed to be the [[OnlySaneMan moral center]] of the group. In Burning Crusade, he's killed as part of Illidan's army, but then he CameBackWrong to reveal he had betrayed him to the Legion and was trying to summon Kil'jaeden so the Burning Legion can destroy Azeroth, killing his own people when they tried to stop him. It's heavily implied that point either the feel magic reanimating him just threw him completely off the slope, or his corpse was just being used by a demon that took on traits of his personality and memory.
** Illidan was always a self-serving {{Jerkass}}, but he had a more gentle side to him and never intended his collateral damage. After nearly being killed by Arthas, though, that gentle side was replaced in Burning Crusade with paranoia, insanity and a desire to crush anyone he deems as a threat, which happens to be ''everyone not on his side.'' The jump was severe enough that Blizzard went [[WordOfGod on record]] expressing a desire to [[CharacterRerailment bring him back for a proper redemption]]. He finally returns in ''Legion'' once more a morally ambiguous character whose positive sides are seen in the greater light. At one point, it seems a little exaggerated; there's a whole questline mostly dedicated to an {{Energy Being|s}} explaining everything in Illidan's past in a positive light as possible. However, when it actually encounters Illidan, it's shown that the god-like Energy Being is just being kind of dumb, and he doesn't conform to its expectations. He ''wants'' to be an AntiHero, not TheChosenOne by someone else's rules.
--> "The Light will heal your scars."
--> "I ''am'' my scars!"
** Malygos from ''VideoGame/WorldOfWarcraft'' goes from a dragon who wants to rein in mortal spellcasters because he disapproves of their methods to a dangerously extreme tyrant who, driven by the idea that widespread overuse of magic will destroy Azeroth, engages in a plan to redirect and control magic that has an excellent chance of destroying Azeroth ''faster''.
** Garrosh Hellscream was always a jerkass with [[FreudianExcuse Daddy Issues]], but when Thrall put him in charge of the Horde, he began committing war crime after war crime (eventually addressed in the novel appropriately titled ''[[Literature/WarCrimes War Crimes]]''). The most notable jumping point though was probably using a mana bomb (essentially a nuke, complete with its own analog for radiation) on Theramore, a city that was founded on and campaigned for peace. Just in case that wasn't enough though, he essentially says to heck with his own people, restores the heart of an EldritchAbomination at the cost of a sacred location, and [[https://www.youtube.com/watch?v=slzQOyS5TqQ declares war on the world]].
** The [[KnightTemplar Scarlet]] [[HeWhoFightsMonsters Crusade]], at least those located within the Scarlet Monastery in Tirisfal Glades can [[FantasticRacism be]] [[WitchHunt accused]] [[ColdBloodedTorture of]] [[KillItWithFire this]]. This in contrast to their forces in the Eastern Plaguelands, who can be sorta excused for their most evil actions due to [[spoiler: their leader being actually a Demon, [[UnwittingPawn who was manipulating them]] to fight the Scourge and [[VanHelsingHateCrimes the sentient undead of the Forsaken]], and then following his VillainousBreakdown outright [[{{Irony}} kills them all and raises them as undead]]]].
** And, while we're on Warcraft games, as you play the human campaign of Warcraft III, Arthas starts out as a dedicated disciple of Uther Lightbringer (even though Arthas is a prince, Uther's military rank is higher than Arthas's, and they both respect that) but gradually starts getting more and more desperate in his fight against the Undead. Eventually, [[spoiler: he betrays Lordaeron, dons an evil looking armor, and murders his own father]]. In his case, though, while he had a decline, the [[MoralEventHorizon jumping point]] was the result of taking up a cursed sword that he was too desperate to realize was a trap that stole the soul of ''anyone'' it touched.
** Also happened to Sylvanas between ''Wrath of the Lich King'' and ''Cataclysm'', although she was already on the thin line between TokenEvilTeammate and NominalHero before. Long story short, she [[DrivenToSuicide died]], [[TheNothingAfterDeath didn't like what she found there]] '''[[{{Hell}} at all]]''', and has done everything she could to avoid dying again ever since. [[spoiler:In service of this, she's entered a pact with the ruler of the afterlife she witnessed and has begun providing him souls, starting with the civilian population of Teldrassil]].
* ''VideoGame/StarCraft'':
** Arcturus Mengsk of started out as a dashing rebel leader who saved you and Jim Raynor from the Confederacy for killing Zerg. The first time he used a psi emitter to summon the Zerg it was a military target and the rebels helped the majority of civilians flee. Then he dumped several on Tarsonis, a planet with a population of two ''billion'', before attacking the Protoss who came to stop the Zerg, using the orbital defenses to stop anybody from fleeing, and abandoning his second-in-command to the Swarm ([[spoiler:admittedly, said second-in-command was the assassin who'd murdered his family, setting him down the path of vengeance even though she didn't remember it]]). And it doesn't stop there: while he didn't count on Kerrigan returning from there as the superpowered leader of the Zerg, it leads to him using ever-more desperate measures to kill her:
*** Setting an imprisoned pal of Raynor's free in exchange for her death (even after seeing her restored to human-ish form);
*** Attacking a ship carrying his own son due to Kerrigan being onboard;
*** Relocating the artifact that has a huge anti-Zerg effect (crippling his own army);
*** Working with mad scientists to create Protoss-Zerg hybrids, inadvertently furthering the local EldritchAbomination's plan to destroy Terrans and Protoss;
*** Blowing up a prison ship (with the crew still onboard) trying to kill Raynor and Kerrigan;
*** And finally, dropping ''nukes'' on his own home PlanetVille once the Zerg make landfall. Note that after his rebellion (caused by his family's murder), Korhal was nuked by a thousand full-strength missiles by the Confederacy, an event so horrific it rendered the planet uninhabitable for years and used as the justification for the SlapOnTheWristNuke (while one Brood War mission had him use nukes on Korhal, it was still radioactive desert then). Talk about BecameTheirOwnAntithesis...
* ''VideoGame/{{Overwatch}}'': the first truly evil thing we see Reyes do is to get in a fight with Jack Morrison that destroys Overwatch's Swiss [=HQ=] and "kills" them both, all because [[DisproportionateRetribution Reyes was passed over for leadership of Overwatch]]. ''This'' is what leads him to become the terrorist and master assassin Reaper. It's especially jarring given that, from what we see of Reyes in the "Uprising" event and corresponding comic, he's downright amicable if a little unhelpful, but certainly a far cry from the soul-stealing, death-obsessed maniac that is Reaper.
* ''VisualNovel/SayaNoUta'' has the revelation that the "fruit" Fuminori had been enjoying eating is actually [[ImAHumanitarian human flesh]]. This presents two options for the player: have Saya fix your screwed perception of reality, which leads to an early end to the story; or embrace your newfound taste for cannibalism, which continues the story.
* In ''VideoGame/MitadakeHigh'' it is common for someone to RP themselves going insane as a result of the madness going on around them. Unfortunately, not everyone is any good at it.
* ''Franchise/FireEmblem'':
** In ''VideoGame/FireEmblemPathOfRadiance'', the country of Crimea is good with bits of gray, Daein is dark gray but with evil leaders, and conservative Begnion was in the middle with its corrupt Senate but well-intentioned leaders. When the sequel rolled around and Begnion became the main antagonist, it became more ruthless.
** If [[PlayerCharacter Byleth]] does not ally with them after the TimeSkip in ''VideoGame/FireEmblemThreeHouses'', [[spoiler:both Edelgard and Dimitri succumb to their extremism and insanity, respectively. This ends up resulting in their deaths]].
* ''VideoGame/FinalFantasyVII'' - Sephiroth is initially the best SOLDIER in the world, but after finding out a certain fact about himself, he becomes a murderous psychopath, slaughtering the population of a village and burning it to the ground, and then sets out to destroy the world.
* In ''VideoGame/FinalFantasyXI'' [[spoiler:after the woman that he loved was killed and he was left for dead by Ulrich during the Multinational Expedition to the Northlands, Raogrimm kills Ulrich. Then he hunts down and murders the rest of the people in the Multinational Expedition because they knew that Ulrich had done something and didn't say anything about it. Then he gets a giant "Slip 'N Slide" and whisks down the slope gleefully as he declares war on the human nations and nearly destroys the world. Mind you, some of it may have been the Dark Divinity Odin fanning the flames of his rage, but still... Although, Ulrich's actions during the Multinational Expedition could be considered the ultimate slippery slope since they were the cause of pretty much all of the major, world-threatening troubles that Vana'Diel has faced in the following 30 years were stemmed from his (accidental) murder of Cornelia]].
** Subverted in the ''Rise of the Zilart'' expansion as [[spoiler: Kam'lanaut and Eald'narche were always trying to [[TheEndOfTheWorldAsWeKnowIt "open the Gates to Paradise"]]]].
* Minister Caudecus in ''VideoGame/GuildWars2'' was always a political rival to the heroic Queen, casting him in a negative light. However, his political stance often made a good point about things that were going ignored. Even when he revealed himself to be the leader of an evil organization, he was still pointing out flaws in the heroes and was revealing actual truths about the past. Once he's actually confronted, among other things, he reveals that he backstabbed his own wife, shoots [[spoiler:his own daughter dead]], and is cackling about how evil he is, dispelling any ambiguity in bringing him down.
* So many in ''VideoGame/DragonAgeII'', a game where [[GreyAndGrayMorality no one is really evil and no one is truly good]]. By the end of the game, both of the leaders of the two warring factions give into their inner demons with [[spoiler: Meredith, the Knight-Commander of the Templars calling for the execution of all mages in the city of Kirkwall for the actions of just one rogue mage who also jumped off the slippery slope and First Enchanter Orsino, leader of the mages, using BloodMagic in an act of despair]]. Both slopes were [[TheDarkSide greased with phlebotinum]] in this case; [[spoiler: Meredith was being corrupted by the lyrium idol in addition to her own paranoia, and the rogue mage was possessed by a demon of Vengeance]].
* Adele in ''VideoGame/ArcRiseFantasia'' jumps right off the slope and onto the [[AxCrazy crazy train]] the ''very instant'' she finds out that she's an [[ChildhoodFriendRomance Unlucky Childhood Friend]], taking this trope to a ''terrifying'' degree.
* The Protagonist from the ''VideoGame/SaintsRow'' series gleefully leaps headfirst off of the slope, and then proceeds to nuke it. In the first game, you start off as a [[HeroicMime (mostly) silent]] henchman who more or less indifferently does what Julius, Gat, Lin, Troy, and others tell you without hesitation, and you seem to be a pretty sane individual. While you are killing, you're killing the other gangs for peace, and the cops you kill are corrupt anyway (of course, not counting civilian casualties in your gameplay rampages). But in Saints Row 2, after being betrayed by Julius and being blown up and disfigured to the point of needing severe plastic surgery ([[SlidingScaleOfGameplayAndStoryIntegration which is really just an excuse to make a new character]]), it's implied that you went insane and very much stated that you're paranoid, corrupt with power, take deep pleasure in murder, is only after the city, and nothing short of evil- the only people outclassing you are [[AssholeVictim the gangs you fight and their leaders]], but not by much. As the game goes on, it becomes clearer and clearer that you're not very interested in wiping out the city for peace anymore as your actions become more and more violent and crazy, [[BerserkButton especially after two of your homies, get murdered]]. The only person who ever stood a chance of stopping you, your old boss Julius, turns out to have done it because he [[TooPowerfulToLive realized that you were a dangerous person]]; you kill him while happily stating you have full intentions of taking over the city in any means necessary.
** Johnny Gat qualifies as well.
** ''VideoGame/SaintsRowTheThird'' plays this with most if not all of the main characters, and they each suffer for it. Boss, Gat, Shaundi, Loren, Killbane, Kiki, Temple, and Kia are just some of the names who are guilty of this, and all either die or, with the exception of Boss, can be killed. Boss arguably gets it even worse if s/he chooses to jump off the slippery slope: s/he reverts back to being worse than ever, and a thoroughly despicable person.
** This prominently applies to [[KnightTemplar Cyrus Temple]], the commander of STAG. Initially, he appears to just be a HeroAntagonist, using military force to get rid of the gangsters fighting one another in the streets of Steelport. But as the game continues, his actions grow increasingly harder to justify. He raises the bridges to Steelport, ensuring that any civilians who couldn't vacate the premises beforehand are left at the mercy of the gangs, his soldiers capture Saints members and detain them without due process (twice), his subordinate Kia holds the Saints captive at the Magarac Island statue along with Mayor Burt Reynolds, [[FalseFlagOperation planning to blow the statue up and paint the Saints as terrorists]], and (depending on the player's decisions) he ends up bombing half the city just to get rid of a few gangsters. By the (canonical) opening of ''VideoGame/SaintsRowIV'', after being humiliated and discharged from the military for his actions, instead of having a HeelRealization, Cyrus teams up with a bunch of Middle Eastern terrorists and [[NukeEm fires a nuclear missile]] towards Washington DC, [[NeverMyFault purely to spite the people who he feels "ruined America"]] (even though that's basically what he's going to do). Needless to say, no tears will be shed for Temple when the Boss kills him by shooting him so that he falls into a vat of liquid metal, and then destroys his nuke in mid-air.
* Two examples from ''VideoGame/BattleTech'':
** The first, and main, example of this in the game is of Captain Samuel Ostergaard, who starts off as a relatively reasonable and calm commander of a small Taurian fleet. When his son killed by the heroes when the player raids an illegal gun-running facility, he is consumed by rage at the player and their allies. Afterwards, his navy is called in to fight the protagonists' faction due to attacks on his home planet [[spoiler:(that were actually staged by the main antagonist in order to start a war)]], he sends wave after wave of soldiers after the heroes. While he's still somewhat stable at this point he fully loses it soon afterwards. When [[spoiler:the truth that his "allies" framed the protagonists for attacking the civilians on his homeworld is revealed]] and is ordered to cease his attack, he [[spoiler: starts a mutiny and seizes command of the fleet, barricades himself in the control room, and attempts to use the fleet to kill the protagonists, disregarding the order to stand down.]] [[spoiler: After the heroes use a certain ChekhovsGun to thwart his attempted attack by remotely detonating the fleet's fuel reserves, he dies when his ship collides with the planet he was going to attack - all to "avenge" the loss of his son.]]
** The other example is played rather sympathetically. [[spoiler: Victoria Espinosa starts off as a loving cousin of the player's friend, Queen Kamea Arano. When her father seizes power from on Kamea's coronation day, she ends up becoming Kamea's fiercest enemy. She participates in the aforementioned attacks on civilians]], which takes a heavy toll on her. When her father surrenders and orders her to stand down, she snaps. [[spoiler: Killing her is the final mission of the game.]]
* The Illusive Man from the ''Franchise/MassEffect'' trilogy takes a flying leap off the slope in ''VideoGame/MassEffect3''. Whereas before he was a WellIntentionedExtremist who tended toward a lot of ShootTheDog moments in his zeal to protect humanity, in the third game he flies straight off the rails and starts using Reaper technology to assemble a massive army of BrainwashedAndCrazy {{Mooks}}, ordering the murders of civilians, and actively working to undermine the Alliance and the Council in their efforts to defend the galaxy against the Reapers. Eventually, it's revealed that he has completely hurdled the MoralEventHorizon with [[spoiler:Sanctuary, a supposed safe haven for refugees from the Reaper attacks, which turns out to be a laboratory where the refugees are forcibly converted into Husks as part of his research into finding a way to control the Reapers]]. Explained by the fact that he was [[spoiler:indoctrinated by the Reapers for the entire game]].
* ''VideoGame/CallOfDutyAdvancedWarfare'': Irons is a firm believer that HobbesWasRight, and plans [[spoiler: to unite the world under Atlas after toppling the world's governments. After a conventional invasion of the United States fails and the free world unites against him, Irons' next course of action is to hit every military installation in the world with biological weapons that'll kill anyone not registered with Atlas]].
* In the ''VideoGame/StarTrekOnline: Delta Rising'' mission "All that Glitters", Vaadwaur leader Gaul lures you to a meeting with what sounds like an offer of a peace settlement, with the stipulation that the Kobali release to him the cache of stasis chambers containing Vaadwaur soldiers from the 15th century whom [[DesignatedHero they've been using as reproductive stock]]. Sounds perfectly reasonable at first, but then he says he wants the Alliance to pull a FaceHeelTurn. Upon being informed that the Federation-led alliance wants ''actual'' peace, as in an end to the Supremacy's war of conquest, he loses his shit, starts gunning down Talaxians, and [[NeverMyFault blames you for it]].
* The ''[[Franchise/TheWitcher Witcher]]'' games might as well be called "Radovid of Redania Jumps Off the Slippery Slope". In the [[VideoGame/TheWitcher first game]], he's a pragmatist who seems genuinely horrified by what his allies of convenience got up to. In the [[VideoGame/TheWitcher2AssassinsOfKings second]], he's a ruthless bastard who tortures people and takes every opportunity to expand his domain. In the [[VideoGame/TheWitcher3WildHunt third]], he's a murderous fanatic who even makes [[EvilEmpire Nilfgaard]] look good by comparison. All of this takes place over less than a year of in-universe time.
* ''VideoGame/{{Prototype}}'': In the first game, [[ArmiesAreEvil Blackwatch]] was at least attempting to contain the infection, if in a brutal, violent, and ruthless manner. By the [[VideoGame/{{Prototype 2}} second game]], they've reached the point where they're deliberately kidnapping civilians just so GENTEK scientists can run "experiments" on them involving throwing Infected beasts at them and watching them get shredded. Dialogue from the Blackboxes also further underscores Blackwatch's expanding psychopathy, including a recording of a Blackwatch soldier shooting an autistic boy on the mere suspicion that he was infected, another Blackwatch soldier shooting a woman immediately after warning her he was authorized to use lethal force if she didn't step back, an officer threatening to discharge another Blackwatch trooper for ''saving a woman from being raped'', a recording from Colonel Rooks explicitly stating that it isn't their responsibility to police the refugees even when they start killing each other, and an officer berating a subordinate for shooting an entire family ''because he was wasting ammo''.
* ''{{Franchise/Halo}}'':
** The Ur-Didact, the villain of ''{{VideoGame/Halo 4}}''. In the [[Literature/HaloCryptum first]] [[Literature/HaloPrimordium two]] novels of ''Literature/TheForerunnerSaga'', he starts off as a conflicted general who strongly disliked humanity and believed that the Forerunners were the rightful masters of the galaxy, but nonetheless also grew to respect humans as fellow warriors, and believed that the Forerunners also had a responsibility to protect and preserve even those species who would stand against them (except [[TheVirus the Flood]], obviously), opposing [[GodzillaThreshold the firing of the Halos to stop the Flood]] precisely because it would kill off ''all'' sentient life in the galaxy. And then he gets {{Mind Rape}}d by the Flood Gravemind, an experience which magnifies his Forerunner supremacism and dislike of humanity into ANaziByAnyOtherName levels. Afterwards, he comes to the conclusion that the only way to defeat the Flood without using the Halos would be to transform his Promethean followers into robotic abominations; when he starts running out of volunteers, he begins forcibly converting humans (making him not that different from the Flood), with the intent to eventually wipe out ''all'' humans and any other species who oppose Forerunner rule. The Ur-Didact's transition from tragic hero to [[DarthVaderClone genocidal dictator in skeleton armor]] is covered in ''Literature/HaloSilentium'' and the ''Halo 4'' terminals.
** TheReveal of ''VideoGame/Halo5Guardians'' pulls this with [[spoiler:your AI companion Cortana]], who in the [[VideoGame/{{Halo 4}} previous game]] [[spoiler:remained the Chief's friend even as her digital body collapsed and she struggled to remain sane, eventually doing a HeroicSacrifice with the last of her strength]]. In the following game, [[spoiler:she turns out to be alive and supposedly repaired, but now she's at best WellIntentionedExtremist who's going to take over the galaxy with her army of enormous Guardian machines. While she keeps insisting that she has good reasons for doing so]], it's clearly bordering on WouldBeRudeToSayGenocide, especially when [[spoiler:she imprisons Chief and Blue Team in a Cryptum so they won't interfere with her schemes]].
* ''VideoGame/SuperPaperMario'': Blumiere's father started out as a ControlFreak who refused to let his son leave the castle. When he found out his son fell in love with Timpani, he blackmailed her into breaking up with him from behind the scenes. When that failed, he finally took a direct approach in an attempt to keep the union of his son and her from diluting his tribe's bloodline. [[spoiler:He cursed her to wander between dimensions, almost killing her in the process.]]
[[/folder]]

* CJ and Niko Bellic from ''VideoGame/GrandTheftAutoSanAndreas'' and ''VideoGame/GrandTheftAutoIV'', respectively. Let's assume that they're good-hearted people at the start (if the cut-scenes are any indication), and let's assume the player doesn't do any killing not encouraged by the storyline (which is a stretch but go with it). Now watch how their lives unfold. CJ, in particular, goes from "I guess I'll kill this guy since he's been screwing with my gang" to "guess I'll just kill all these guys for no apparent reason" so quickly it might make you wonder if you're still playing as the same guy. By the end of the game, at least, he gets to see the awful results of his actions, and he tells his family outright in the final cutscene that they need to rein it in and be more subtle. It helps that he was being blackmailed for the entire game. His brother has fewer excuses, and the other Grove [=OGs=] have none.
** Well, Niko may seem pretty nice at the beginning of the game, but the plot [[spoiler:eventually reveals that he is a war criminal out to kill other war criminals]]. So there's a good argument that he starts the game as a major bad guy, and indeed committed even more horrible acts before the game started than you can ever do in it.

* Notably averted by Alan Grant's [[Franchise/TheDCU DC Universe]] character of ComicBook/{{Anarky}}: where originally the character was scripted to be willing to murder in pursuance of his anarchic philosophy, as written he upholds the same moral standards as Franchise/{{Batman}}, which makes for some nice NotSoDifferent interactions.

** The Ur-Didact, the villain of ''{{VideoGame/Halo 4}}''. In the [[Literature/HaloCryptum first]] [[Literature/HaloPrimordium two]] novels of ''Literature/TheForerunnerSaga'', he starts off as a conflicted general who strongly disliked humanity and believed that the Forerunners were the rightful masters of the galaxy, but nonetheless also grew to respect humans as fellow warriors, and believed that the Forerunners also had a responsibility to protect and preserve even those species who would stand against them (except [[TheVirus the Flood]], obviously), opposing [[GodzillaThreshold the firing of the Halos to stop the Flood]] precisely because it would kill off ''all'' sentient life in the galaxy. And then he gets {{Mind Rape}}d by the Flood Gravemind, an experience which magnifies his Forerunner supremacism and dislike of humanity into ANaziByAnyOtherName levels. Afterwards, he comes to the conclusion that the only way to defeat the Flood without using the Halos would be to transform his Promethean followers into robotic abominations; when he starts running out of volunteers, he begins forcibly converting humans (making him NotSoDifferent from the Flood), with the intent to eventually wipe out ''all'' humans and any other species who oppose Forerunner rule. The Ur-Didact's transition from tragic hero to [[DarthVaderClone genocidal dictator in skeleton armor]] is covered in ''Literature/HaloSilentium'' and the ''Halo 4'' terminals.

A form of DebateAndSwitch, because they never ''really'' address the question of whether the original ambiguous action was acceptable or not. Also helps to [[StatusQuoIsGod maintain the status quo]] by ensuring the main characters never question their own morality too closely, thus keeping the more simpler BlackAndWhiteMorality from [[GrayingMorality degrading]] into GreyAndGrayMorality, as well as prevent a potential case of StrawmanHasAPoint. Compare SlowlySlippingIntoEvil for a longer, more developed process of going from "ambiguous" to "evil".

* The Protagonist from the ''VideoGame/SaintsRow'' series gleefully leaps headfirst off of the slope, and then proceeds to nuke it. In the first game, you start off as a [[HeroicMime (mostly) silent]] henchman who more or less indifferently does what Julius, Gat, Lin, Troy, and others tell you without hesitation, and you seem to be a pretty sane individual. While you are killing, you're killing the other gangs for peace, and the cops you kill are corrupt anyway (of course, not counting civilian casualties in your gameplay rampages). But in Saints Row 2, after being betrayed by Julius and being blown up and disfigured to the point of needing severe plastic surgery ([[SlidingScaleOfGameplayAndStoryIntegration which is really just an excuse to make a new character]]), it's implied that you went insane and very much stated that you're paranoid, corrupt with power, take deep pleasure in murder, is only after the city, and nothing short of evil- the only people outclassing you are [[AssholeVictim the gangs you fight and their leaders]], but not by much. As the game goes on, it becomes clearer and clearer that you're not very interested in wiping out the city for peace anymore as your actions become more and more violent and CrazyAwesome, [[BerserkButton , especially after two of your homies, get murdered]]. The only person who ever stood a chance of stopping you, your old boss Julius, turns out to have done it because he [[TooPowerfulToLive realized that you were a dangerous person]]; you kill him while happily stating you have full intentions of taking over the city in any means necessary.

** Anakin Skywalker from the prequels. Specifically, note how quickly he goes from [[spoiler:agonizing over his role in Mace Windu's death]] to [[spoiler:killing younglings without a problem]]. Anakin finally slips so far, his own wife, Padme Amidala, loses the will to live and eventually dies, and Obi-Wan Kenobi is forced to duel him, ending gruesomely. In order to keep Anakin alive, Emperor Palpatine, a.k.a. Darth Sidious subjects him to painful body reconstruction. The final push to the Dark Side comes from Palpatine himself- when Anakin asks if Padme is still alive, the Emperor tells him in his anger, he killed her. In pure disbelief of this, Anakin's true power flares up, and he screams out in despair, fully overtaken with pain and hate, completing his transformation into Darth Vader. What was especially loathsome of him was that, rather than desiring everyone's well-being, his honest desire for good was corrupted into infatuation and affection (he wanted to be together with her, alive, rather than desiring what's best for everyone); a desire to be with her for the sake of his pride; to feel good about himself for being able to keep the people he knows personally from dying (although, sadly for him, Palpatine never had any concern for his wife, to begin with).

* ''WesternAnimation/KimPossible'': Each member of Team Impossible; went from just being a PunchClockHero who [[RemovingTheRival wanted Kim to stop saving the world so they could get paid for doing it themselves]], and basically straight to trying to permanently end her heroics.

* ''TabletopGame/WorldOfDarkness'' has a mechanic for this: [[KarmaMeter Morality]] degredation. Every type of playable creature has some form of a KarmaMeter that goes from 0 to 10, although some are [[BlueAndOrangeMorality stranger]] than others (Werewolves have to balance their opposing natures, so 5 Harmony is the ideal and breaking points get you to extremes, Demons' Cover measures how well they hide from the God-Machine, Changelings' Clarity doubles as a SanityMeter, and so on). 10 is IncorruptiblePurePureness, 7 is assumed to be the normal starting point, and at 0 your character becomes unplayable (Humans become [[TheSociopath sociopaths]], Vampires become mindless monsters, Changelings completely detach from reality, et cetera). Commit some act that a person at your level of morality would view as 'bad' makes you roll for Degradation, and if you fail the roll you lose a point, and possibly gain a derangement. While each level down takes greater and greater sins (falling from 1 to 0 requires serious atrocities), as your morality gets lower and lower, you stop caring about the harm you're causing, which can make it easier for you to do worse and worse things.