History Main / TheDarkSideWillMakeYouForget

--> '''The Illusive Man:''' Cerberus ''is'' humanity!\\\

*** This was the revelation about Nergal learned in chapter 19x2, the most difficult bonus chapter to receive in the game. [[spoiler:It turns out that Nergal is the father of Nils and Ninian. His research of the dark arts was so that he could find a way to open the Dragon's Gate and be reunited with his children. But the dark magic so corrupted his mind that he forgot the second half of this motive and ended up concluding that the reason he wanted to open Dragon's Gate was so he could destroy the world with dragons ForTheEvulz.]]

*** The other source happens to be [[spoiler: Teodor]], also in 19x2, who explicitly says that this has to happen to anyone who wants to be really good with dark magic. Yikes.

* ''VideoGame/TheLegendOfZeldaTheWindWaker'' implies this was what happened to [[BigBad Ganondorf]]. He initially set out to conquer Hyrule because he envied its idyllic nature while his people lived in a harsh desert... but when he laid hands on the Triforce, seven years later all he'd changed is that now the rest of Hyrule is even ''worse'' than the desert while he chased the missing pieces of the Triforce. ''[[VideoGame/TheLegendOfZeldaSkywardSword Skyward Sword]]'' actually gives an explanation for this- he's the incarnation of a {{God Of Evil}}'s hatred, so no matter what his starting goal, TheDarkSide ''will'' eventually corrupt it into generic EvilOverlord-ism.

* Roderick Burgess from the Netflix version of ''Series/TheSandman'' makes an attempt to summon and imprison Death, and does so at least in part because he wants Death to return his son Randall to life, which gives him a more sympathetic motive than his comic book counterpart, who only ever wanted immortality and power. When the spell goes awry and catches Death's brother [[AnthropomorphicPersonification Dream]] instead, Burgess is quick to drop any more sympathetic motivations after he steals Dream's magical tools and starts using them for his own material benefit.

** Sasuke is a poster child for this. While he was always firstly driven by his wish to take vengeance upon his brother for murdering their family, his time in Konoha made him connect to the members of his team. The lure of revenge was too great, until he decided to break those ties. [[spoiler:[[MotiveDecay His motives have rapidly degenerated]] after joining with Tobi. Initially after learning of the truth behind his brother's murder of his clan, Sasuke simply wanted revenge against the Village Elders who manipulated him. Now he won't settle for anything less than the complete genocide of anyone who lives in Konoha. There's some hints that Sasuke is being influenced by something (Madara claims the Uchiha bloodline is TheDarkSide), probably an AuthorsSavingThrow given that during the summit arc he rather suddenly turns into a cardboard villain after gaining Susanoo (amongst other things, he abandoned another set of teammates that he seemed to care about earlier, who in the previous arc had saved him from being killed)]].

** Originally, Zamasu just wanted the gods to be more involved with mortal affairs so they would stop misusing the knowledge giving to them by the gods. At worst, he wanted the gods to stop protecting mortals since [[HumansAreBastards they're not worth it]]. After he meets and fights Goku, however, he goes off the deep end and decides that mortals are foolish ''and'' dangerous and need to be destroyed for the peace of the universe. [[spoiler:To that end, he kills his own master, takes his Time Ring, uses the Super Dragon Balls to take Goku's body, and murders him and his family [[EvilIsPetty out of spite]]. By the time Zamasu (now Goku Black) reaches Earth, he's wiped out all the gods in the future timeline, is clearly insane, and sees himself as the one true god of TheMultiverse along with Future Zamasu.]] Whatever nobility he may have had in his goals is long gone.
** In ''Anime/DragonBallSuperBroly'', it can be argued that Paragus ''might'' have cared about Broly in the beginning much like [[Anime/DragonBallZBrolyTheLegendarySuperSaiyan his 1993 counterpart]], as shown by his frantic literal flight from King Vegeta's palace to rescue his son from Vampa. However, his obsessive vengeance quest eventually wore away any compassion he may had for his boy; and compounded with four ''decades'' of isolation on a hellish DeathWorld, warped what little remaining love he had for Broly into a sense of possessive entitlement; an all too sadly common trait among parents who hate their talented children yet still mooch off their success through guilt trips. To his credit however, Paragus ''eventually'' remembers how much he loved Broly when he thinks he's about to lose him. [[HeelFaceDoorSlam Unfortunately]], by the time he realizes this, Frieza had other ideas...

* ''Manga/VinlandSaga'': [[spoiler:Once Canute ascends to the throne of England]] he finds himself doing more and more DirtyBusiness to hold on to his power, in order to honour the promise he made [[spoiler:to Askeladd to build a better world]]. By the time he re-unites with Thorfinn, the stresses of his office and the constant taunts of his SpiritAdvisor has made him [[GenerationXerox close to a carbon copy of his father]].

* In ''ComicBook/TheTransformersIDW'' continuity, the Decepticons started out as heroic freedom fighters rebelling against the corrupt Senate. But after they overthrew the Senate, Megatron slowly became convinced that he and ''only'' he was right, resulting in the Decepticons becoming conquerers. That coupled with Megatron's [[FantasticRacism bigotry towards organic races]] and his emotional and mental manipulation of his soldiers, resulted in the Decepticons fighting for the same type of oppression that they were born to overthrow.

* In ''ComicBook/OldManLogan'', Magneto (the holocaust victim) works with Red Skull (the Nazi) to bring down the heroes of the Marvel universe alongside other super-villains.

* ''ComicBook/SonicTheHedgehogArchieComics'': Dimitri, Knuckles's ancestor, once sought to restore the Floating Island to its original home in the ground and after his plan to siphon the energies of the Chaos Emeralds was rejected he still went ahead with it, believing he could fix their home. The machine overloaded and infused him with the Chaos Energies and he was reborn as the villain Enerjak. In his new role he simply sought a technological empire with him at its head, DrunkOnTheDarkSide with his God-like powers. After being de-powered though, Dimitri's sanity gradually returns and he eventually pulls a HeelFaceTurn, his old beliefs in helping his people having resurfaced.

** This is the main reason the [[spoiler: Dark Phoenix]] is such a threat as [[spoiler: the Phoenix]] by nature amplifies emotions, and is amplified by them in turn: "Good becomes great, bad becomes worse." A key example is the original [[spoiler: Dark Phoenix]], [[spoiler: Surtur]]. He started out as a benevolent mage-scientist on a dying world, who begged for the chance to save it and his people, summoning [[spoiler: the Phoenix]], the EnigmaticEmpoweringEntity in question, then pointedly breaking the summoning circle because all he wanted was to plead his case, not try and bind [[spoiler: Her]]... and then ultimately spiralled into AGodAmI into [[OmnicidalManiac a desire to destroy everything]] and rebuild it 'better'. Oh, and in the process, he destroyed an entire galaxy. Having slaughtered all his people and enslaved their souls as his wraith-like monstrous minions, under the genuine delusion that he was doing them a favour.

* Simba in ''Fanfic/TheLionKingAdventures''. He goes from a sweet, mischievous cub to an [[spoiler: evil, vicious killer. Initially, he's doing it to try finding a way to bring back the destroyed Pride Lands. However, it soon turns into a desire to become the greatest predator.]]

** This is a running theme with [[SuperPoweredEvilSide Nightmares]] in general: most are driven with a genuinely benevolent or reasonable goal, but the power of a Nightmare comes with going insane. As a result, the majority of Nightmares become so lost in their goal they lose sight of the core attributes of it or begin doing things that they never would've done. There's a good reason the universal reaction a purified Nightmare has upon returning to sanity is MyGodWhatHaveIDone.
* In ''Fanfic/HopeForTheHeartless'' (in which [[WesternAnimation/TheBlackCauldron the Horned King]] is [[ResurrectedForAJob brought back to life]] and half-forced on [[ImpossibleTask a seemingly impossible]] RedemptionQuest), it's revealed that the [[OurLichesAreDifferent lich]] ([[ReallySevenHundredYearsOld who has existed over a thousand years]]) has forgotten many things from his past in his centuries lasting quest to find [[ArtifactOfDoom the Black Cauldron]] in order to TakeOverTheWorld, viewing memories to be [[PragmaticVillainy a distraction]]. He doesn't remember how to feel because his heart died out with the countless sins he committed, or the reason he wanted to conquer the world in the first place, or who he was before becoming [[EvilMentor Arawn's]] apprentice. However, over the many months he spends with his MoralityPet, [[LivingEmotionalCrutch Avalina]], he gains some flashbacks from his past and [[WhatIsThisFeeling starts feeling]] [[FirstTimeFeeling positive emotions again]], [[spoiler:even regaining his heart]].

* ''Film/StarTrekGenerations''. Soran. He lost his family to the Borg, and eventually ended up killing hundreds of millions of beings just to enter The Nexus. When Picard tries to use the memory of his family to convince Soran to stop his plan, he pauses and looks distraught... then [[SmugSnake smirks]] and replies, "Nice try." This, implying that he knows this trope is in effect and just doesn't care, makes him ''less'' sympathetic.

It's outright stated by Rand that the reason he... freezes on the inside is because now he has (against his will, but that doesn't seem to matter to him) lucidly attempted to murder ([[BattleHarem one of]]) the woman he loves. The scenario is laid out in this passage (probably to preemptively [[AvertedTrope avert]] people thinking it was the True Power):

** When Frodo offers her the Ring Galadriel says that she would become a new Queen, not dark but beautiful and terrible and that "All shall love me and despair!" but she resists the temptation to take it.

** This is even the case for Melkor/Morgoth. He started out just wanting to create something of his own, and devolved into wanting to destroy everything he personally hadn't created.

* Jacen Solo in ''Literature/LegacyOfTheForce'' (part of ''Franchise/StarWarsLegends'') ends up this way as a result of the philosophical growth he goes through that's necessary to save the galaxy without committing genocide. Twice invoked, as another reason he started down that path was because of a vision in which he and Luke fight to the death. Naturally, by the end he no longer cares if Luke dies.

* In Creator/GuyGavrielKay's ''Literature/{{Tigana}}'', a woman infiltrated a court in order to kill the king. But she worked so hard at the infiltration that when she actually got a chance to kill him, she saved his life, and after that she actively helped him.
* In John Marco's ''Tyrants and Kings'' trilogy, this applies to Emperor Arkus and all his top lieutenants. In the beginning of his Black Renaissance they signed on to [[UtopiaJustifiesTheMeans establish order and civilization on a continent wracked with war and devastation]]. But decades of conquest and immortality has corrupted them all, to the point everyone realizes they are irredeemable.

* The Inquisitors of Disney's ''Franchise/StarWars'' have been revealed to have been all former Jedi, most of whom were padawans that were captured, tortured and brainwashed into serving the very people that destroyed their lives, their homes, their friends, their mentors, their Order, and the Republic.
* In ''Literature/TheBlackSpider'', Christine makes a deal with the devil to protect the villagers from a feudal lord, and then she tries to scam him out. She is turned into a monstrous spider in punishment, whereupon she loses her personality, memories and identity and completely forgets her well-meaning goals, becoming nothing but a merciless killing machine.

* Sam Winchester from ''Series/{{Supernatural}}'' starts out trying to make the best of his BlessedWithSuck-y demon powers by using them to exorcise demons, hoping to avenge his brother's death at the hands of Lilith. Even when Dean comes BackFromTheDead, Sam remains obsessed with killing Lilith, thinking this will prevent the [[TheEndOfTheWorldAsWeKnowIt Apocalypse]]. With Ruby as his mentor, Sam eventually [[spoiler:drinks [[PsychoSerum demon blood]] to fuel his powers and gets addicted to the stuff. Dean stages a failed intervention and the brothers have a fight which ends in Sam trying to choke Dean and walking out on him. Sam then lets Ruby bleed a possessed woman to gain enough power to finally kill Lilith, knowing this should permanently alter him but expecting to die in the attempt, only to learn that Lilith's death was the final seal which had to be broken [[NiceJobBreakingItHero to free Lucifer]].]]

* [[ProtagonistJourneyToVillain The long-term arc]] of Walter White on ''Series/BreakingBad'', with "the Dark Side" being the dark side of chemistry -- illicit drug production. He starts cooking meth [[HealthcareMotivation to pay for his cancer treatment]] and [[JustifiedCriminal provide for his family's future after he's gone]]. As time goes on, his justification gets more distant and less believable; he begins to start stealing, murdering and even [[spoiler:[[WouldHurtAChild poisoning a kid]]]] to get what he wants -- which is to keep cooking and making money, even though his cancer is in remission and he's made more money than his wife knows what to do with. No wonder creator Vince Gilligan calls the series "How [[Film/GoodbyeMrChips Mr. Chips]] became Film/{{Scarface|1983}}." It's only in the series finale that he admits that the ''real'' reason he kept cooking meth was because he enjoyed finally being successful at something.

** All of the surviving Chaos Primarchs. Magnus once wanted to spread knowledge, now his main desire is payback against the Imperium and especially the Space Wolves. Perturabo wanted to be respected; now he lurks on a Daemon World, the prisoner of his own resentment. Angron wanted revenge for the deaths of the only family he ever knew; now the party responsible has been effectively dead for ten millennia, but Angron doesn't care because he lives solely for killing. Mortarion once sought to end the threat of psykers; now he only wants dominion. Fulgrim's quest for perfection - and his Legion's - became a non-stop pursuit of excess. Lorgar is about the only one to remain reasonably clear, since his motivation before and after his fall to Chaos was the spread of faith; all that changed was faith in ''what''. The remaining three are Horus (DeaderThanDead), Konrad Curze (regular dead), and Alpharius Omegon([[MindScrew who the hell even knows at this point]][[spoiler:Alpharius died so hard his twin felt it from lightyears away]]).

* ''Theatre/SweeneyToddTheDemonBarberOfFleetStreet'': The title character's whole story-arc is motivation decay using this trope. By the time that he finally [[spoiler:takes vengeance upon Judge Turpin]], Sweeney has gone quite murderously insane, and is so far gone that [[spoiler:he fails to recognize his own daughter and tries to kill her]]. He's only snapped out of it in the end by [[spoiler:the realization that the beggar woman he killed just prior to killing Turpin was none other than his wife Lucy, who Sweeney had gone on this whole thing to avenge, because his partner Mrs. Lovett didn't tell him that Lucy was still alive]].

* In ''Theatre/{{Dreamgirls}}'', both the play and the film, the Dreamettes' manager Curtis' morally questionable actions in the first act were for the betterment of the group in the face of a racist system. Come the 70's, however, much of that racism has faded but he's still shady. At this point it's clear that his only motivation is money and being in control.

** ''VideoGame/FireEmblemAwakening'': Supports in [=SpotPass=] reveal this to be the case with Gangrel, the first ArcVillain of the game. [[spoiler:Walhart's conquest of the continent of Valm worried Gangrel, causing him to start his own unification plan that involved uniting Plegia, Ferox, and Ylisse under himself, so that they could stand up to the Valmese Empire. The power he got from starting the war, and his self-imposed rush to unite the countries, went to his head and caused MotiveDecay; by the time of the game's beginning, his only ''real'' motive is [[WarForFunAndProfit deliberately provoking open war with Ylisse for the hell of it]].]]
* More often than not, this happens to people who use fel magic in ''VideoGame/{{Warcraft}}'' setting. Fel will slowly corrupt the user, turning them evil; in the end they're likely to join the world-destroying Burning Legion in order to get more power. Examples:

*** Sargeras was once TheParagon of Good itself, and is more of a case of HeWhoFightsMonsters when he realized all he was fighting for would be for nothing [[spoiler:if (and in his eyes, ''when'') the [[EldritchAbomination Void Lords]] successfully managed to corrupt a sleeping Titan and turn all of creation into a hellhole]] and his fellow Titans refused to help him, so he decided to purge all creation in fire and destruction [[spoiler:in the faint hope [[WellIntentionedExtremist the universe would start again better prepared to fight off the corruption of the Void Lords]]]]. In this case, demonic energy didn't turn him evil so much as [[EvilMakesYouMonstrous change his appearance to reflect his own new nature]].
*** Gul'dan didn't have any noble goals in turning to the fel; he was just a powerhungry jerk who sold out his race to obtain that power, making him one of the few true villains in the setting who has absolutely no sympathetic qualities to him. His teacher Ner'zhul, on the the other hand, did turn to the fel to help his people, but also had certain selfish motivations, and he eventually loses his redeeming qualities as well.
*** Illidan is...[[HeelFaceRevolvingDoor complicated]]. He originally turned to the fel partially to [[TakesOneToKillOne fight the Burning Legion]] during the War of the Ancients, but also because of [[GreenEyedMonster jealousy towards his brother Malfurion]] and [[HeroicWannabe a desire to be the hero]]. He's done both horrible ''and'' good things with that power ever since, and he's been on both sides of the conflict and [[WildCard his own side]]; heck, he even started an order dedicated to using fel magic to kill demons with his demon hunters. These days, he's a questionably-sane WildCard who's more inclined to kill demons than Azeroth's people, but pretty much [[TheFriendNobodyLikes everybody's still wary of him]].
** Necromancy: Arthas, Kel'Thuzad, Nerzhul (plus fel stuff and being selfish to start with) and all his liches like Ras Frostwhisper, some of the more prominent Death Knights...

** Prince Arthas, particularly in ''Warcraft III''[[note]](''VideoGame/WorldOfWarcraft'' arguably doesn't count because the Lich King had mind melded with him)[[/note]]. Arthas started out wanting to stop the undead scourge; then he wanted to kill Mal'Ganis to avenge the people who had been killed or turned by the undead. Then he becomes a Death Knight, travels back to civilization and immediately starts killing people. While the descent started a bit earlier, the ArtifactOfDoom Frostmourne (and its corrupting influence) was the part that made him completely forget that he ever cared about keeping people alive in the first place.

*** It's even worse than it sounds: [[spoiler:he didn't just decide one day to let a demon into his head. After the second battle he was bleeding out and about to die, cursing himself for being unable to avenge Milleuda. Only then does the Zodiac stone offer him another chance by accepting its power, and he takes it; he was never told the stone held a demon.)]]

** Riku goes through this in the [[VideoGame/KingdomHeartsI first game]]. He starts out using the darkness because he wants to retrieve Kairi's heart. This eventually takes second place to his jealousy of Sora -- after taking the Keyblade, losing the Keyblade and getting his ass kicked, he's willing to open himself completely to the darkness if it means he can be stronger than Sora. [[GrandTheftMe Big mistake.]]
** Completely averted with Terra in [[VideoGame/KingdomHeartsBirthBySleep the prequel]]. Through most of the game he's ''very'' careful with his use of darkness, and never loses sight of his morals or priorities. Unfortunately, he ends up even worse off than Riku.

** Lucien in ''VideoGame/FableII''. He originally wanted to rebuild the Tattered Spire in order to revive his dead wife and daughter, and when he realizes that the protagonist is TheChosenOne destined to stop him, he is visibly shaken when he has to [[spoiler:kill you and your sister.]] However after decades of building the spire on the back of slave labor and dark magic, he's completely forgotten his original purpose for building it, and only wants the power. [[spoiler: This is most obvious the second time he shoots you, in which he'll calmly state he just murdered your family in cold blood, and then kill you without a second glance.]]

* Daisy Fitzroy, the leader of the Vox Populi in ''VideoGame/BioShockInfinite'', ends up thinking she has to kill ''children'' of upper class parents ''on the chance'' they become {{Corrupt Corporate Executive}}s. [[spoiler:The DLC ''Burial At Sea'' subverts this, it shows that this was a BatmanGambit she was doing to get Elizabeth to kill her on behalf of the Lucene twins. She had no intentions of harming Fink's son for real, and was very upset when it was first suggested to her.]]

* In ''VideoGame/PathfinderWrathOfTheRighteous'' the mage Zacharius transformed himself into a lich so he could use the power and immortality to aid the crusade against demonic invaders, but now considers that endeavor an irritating distraction from his real work. He also had the foresight to see this trope coming, and placed himself under a MagicallyBindingContract that forces him to help the crusader who returns his [[SoulJar wand]].

* In ''Franchise/AceAttorney'', Miles Edgeworth start out as a child with the idyllic view that defense attorneys protect the innocent (a view shaped by his father, a defense attorney who was the closest the series had to a BigGood). Following said father's murder and an upbringing by [[spoiler: his murderer,]] [[AmoralAttorney prosecutor Manfred Von Karma]], Edgeworth forgot his childhood beliefs and began to view defense attorneys as obstacles to be crushed on his way to keeping a perfect record of guilty verdicts. As the series goes on, he remains a prosecutor but remembers what he originally knew law was about, focusing his career on uncovering the truth in every case.

* King Lewstrom, the lich necromancer of ''Webcomic/YetAnotherFantasyGamerComic'', is revealed to be this. His backstory is eventually told, and involves him turning to a dark goddess in order to gain revenge on those who killed his family. Centuries later he is a lich and remembers none of this. Upon finding out, he asks his goddess why she never held up her end of the bargain. She claims she did; he out-"lived" all of his enemies.
* It's explicitly mentioned in ''Webcomic/TowerOfGod'' that, on their way to the top, only a rare few remember the reason they originally wanted to climb the tower. Most forget it amidst the power and riches they encounter, and don't realise it until much later, if ever.

* [[spoiler:Cinder Fall]] from ''WebAnimation/{{RWBY}}'' originally just wanted to be [[IJustWantToBeFree free]] of her enslavement. After killing her tormenters and her mentor, she was found by [[TheCorruptor Salem]], who twisted her desire for freedom into a hunger for power. In the present day, she has become so desperate for power that she's accepted Salem as another master to achieve it, sacrificing the freedom she once wanted so badly.

* ''LetsPlay/WitchCraftSMP'': While Scott's initial motive for learning necromacy and soul magic and trying to win the Witch Trials is to bring his partner BackFromTheDead, as he becomes more powerful, he starts slipping towards wanting to become more powerful for the sake of it. [[spoiler:To his credit, he's confronted about it in the finale, he's able to [[HeelRealization recognize the corrupting effects]] of powerful magic and chooses to [[DePower give up on it]] as a requirement to return to his original motive.]]

** Toffee eventually shapes himself as the BigBad of the series. WordOfGod [[https://www.youtube.com/watch?v=bme4NT7FleE compares him]] to Magneto, as someone who is trying to do good in "the wrong way". This might explain his initial [[spoiler:revolt]], but by present time he seems to be just a ManipulativeBastard with no end goal in mind.
** Eventually, this trope is downplayed. Toffee's goal of "good" is in [[spoiler: ridding the realm of magic as he views it as dangerous and something Star comes to agree with.]] On the other hand, later episodes show he was always a jerk (even back as an adolescent, being reminscent of a punk gang leader) and that his complaints seem dishonest since his race, the Septarians, are invulnerable with a strong HealingFactor that only magic can harm. Even most other monsters were afraid of his kind, making his own goals of "good" seem hypocritical when considering his race's own talents and him being afraid of something that can actually hurt him.

** Asajj Ventress spent many of her early years training under a Jedi who treated her with respect and seemed like her happiest days of her life. Then her master gets killed, she goes on a RoaringRampageOfRevenge, Dooku recruits her, she is now his apprentice and she goes around killing Jedi in revenge for not being there for her master.

* The second season of ''WesternAnimation/VoltronLegendaryDefender'', reveal this to be the backstory of Zarkon and Witch Haggar. [[spoiler: Zarkon was a King who was desperately fighting to preserve his dying planet. Witch Haggar was a Altean scientist passionate about her work. The two of them meet and fall in love. Sometime later they discover a rare comet made from a very powerful ore. Zarkon believing the ore is the answer to his planet's problems, and Haggar being fascinated by its unlimited power to the point of obsession, eventually drove both of them into a downward spiral until both of them CameBackWrong.]]

** A ''much'' quicker example happens with [[spoiler:Lotor]]. While he was extremely ruthless, WordOfGod [[http://ew.com/tv/2018/06/15/voltron-season-6-postmortem/ indeed confirms he]] [[WellIntentionedExtremist had good intentions]]. A trip to the quintessence dimension and a BerserkButton turn him into a genocidal sadist.

* ''LetsPlay/WitchCraftSMP'': While Scott's initial motive for learning necromacy and soul magic and trying to win the Witch Trials is to bring his partner BackFromTheDead, as he becomes more powerful, he starts slipping towards wanting to become more powerful for the sake of it. [[spoiler:To his credit, he's confronted about it in the finale, he's able to [[HeelRealization recognize the corrupting effects]] of powerful magic and chooses to give up on it to return to his original motive.]]

* [[spoiler:Cinder Fall]] from ''WebAnimation/{{RWBY}}'' originally just wanted to be [[IJustWantToBeFree free]] of her enslavement. After killing her tormenters and her mentor, she was found by [[TheCorruptor Salem]], who twisted her desire for freedom into a hunger for power. In the present day, she has become so desperate for power that she's accepted Salem as another master to achieve it, sacrificing the freedom she once wanted so badly.

Taking such a morally grey action is a technically neutral action, and in theory, it should be possible to use it to achieve the goal in question without permanently crossing the MoralEventHorizon. But TheDarkSide being The Dark Side, it doesn't work like that. By its very nature, EvilFeelsGood, and there are few highs like being DrunkOnTheDarkSide. ItGetsEasier and easier to choose the dark side. The hero begins SlowlySlippingIntoEvil, gradually drifting further and further away from what they once were, and eventually, they will be a completely different person from before they crossed this line.

* The Templars in the ''VideoGame/AssassinsCreed'' series. While modern society wouldn't begin to agree with their ideas of a plutocracy, their overall goal of creating a utopia where there's no more war and suffering isn't a bad one. But they never reach that point, even by the modern age; the technologies they find combined with the power they already wield by 2012 in the AC Universe would be more than enough to sit down and establish their utopia, or at least parts of it. Instead, even in 2012, they simply keep hoarding more and more power, killing more and more people to get more power, and never reach the point where they feel they should finally sit down and install their utopia instead of killing the Assassins or doing the two aforementioned goals. This is in part due to the continued interference by the Assassins, who are ideologically opposed to them, but their WellIntentionedExtremist stance on UtopiaJustifiesTheMeans keeps falling flat on its face when presented to us, the players, because they never even try to actually install their utopia in the first place, instead feeling they just never have enough control of the populace.
** This gets explained in III: the order as a whole has been carefully manipulated over the ages to provide a framework that instills a sense of... misguidance in its members, leading to their desire for control in all things, leading to acceptance of domination (enslaving others) and subjugation (being enslaved) themselves. You barely see any of the leaders perform a KlingonPromotion; they toss away the lives of innocents to get where they are instead of taking a page from the assassins and just killing their way to the top. This usually results in the few individual Templars too stupid or too egotistic to be brainwashed taking control of the whole damn thing, which is the main reason why the order is so fucked up. The whole point of this was so that, in the event that an Ubermensch took command, that person would rule the entire planet unopposed and well-defended. That person is [[spoiler:Juno, one of the First Civilization survivors, who brain uploaded herself in a bid to take revenge on humanity by using them to warp reality]].

** [[TheNeidermeyer The Illusive Man]]. He begins the game as a reasonable, if morally questionable, authority figure, but progressively gets more questionable, at least from the perspective of a Paragon Shepard..

* Daisy Fitzroy, the leader of the Vox Populi in ''VideoGame/BioShockInfinite'', ends up thinking she has to kill ''children'' of upper class parents ''on the chance'' they become {{Corrupt Corporate Executive}}s. [[spoiler:Burial At Sea subverts this, it shows that this was a Batman Gambit she was doing to get Elizabeth to kill her on behalf of the Lucene twins. She had no intentions of harming Fink's son for real]]

It's outright stated by Rand that the reason he... freezes on the inside is because now he has (against his will, but that doesn't seem to matter to him) lucidly attempted to murder ([[BattleHarem one of]]) the woman he loves. The scenario is laid out in this passage(probably to preemptively [[AvertedTrope avert]] people thinking it was the True Power):

* In ''WebComic/SchlockMercenary'', Xinchub apparently ''used'' to be a WellIntentionedExtremist. By the time the Toughts meet him, however, he's long since become an unrepentant JerkWithAHeartOfJerk who's fully aware that he's "the biggest a-hole in the game". See [[https://www.schlockmercenary.com/2008-02-07 here]].

''BeatPanel''
'''Cetta''' (sarcastically): Happy memories?

* ''Literature/TheWheelOfTime'' has an odd example in protagonist Rand Al'Thor. After he [[spoiler:channels the True Power, which is derived directly from the Dark One (the series' UltimateEvil)]], he undergoes an [[JumpingOffTheSlipperySlope immediate personality change,]] becoming incredibly paranoid, very harsh toward anyone who he perceives as threatening or even disagreeing with him, and abandoning his previous [[WouldntHitAGirl refusal to kill or harm a woman]]. However, the extraordinarily stressful circumstances surrounding [[spoiler:his use of the True Power]] could be considered explanation enough without resorting to this trope -- he had been undergoing SanitySlippage for upwards of six books -- and it may even be considered a subversion considering that he pulls a complete 180 back to the side of good after an epiphany later in the same book.\\\

* In ''Fanfic/{{Spellbound}}'', Felix prepares himself for a Samhain revel by "unrooting" himself from the material world. It's a necessary part of protecting his mind and the secrets he carries, but it leaves him emotionally adrift for months afterwards. And after he [[MercyKill consumes a tormented soul]], his magic power increases but his empathy is permanently damaged.

* While only "evil" in a tongue-in-cheek way, Artefact of ''Sankaku Complex'' was not always a depraved anime-yellow-journalist-slash-pornoblogger. His earlier writings were more gushing and humble in tone (in contrasts with his signature witty DeadpanSnarker style), recommending ''Manga/{{Yotsuba}}'' for learning Japanese, as well as promoting artists, works, or stores he likes. Compare old titles like "Yotsuba-to! – Ideal manga for learning Japanese?" to the typical "Ichiban Ushiro no Dai-Maoh Bukkake Milking Anime" common nowadays.

* ''WesternAnimation/StarWarsRebels''
** According to WordOfGod, The Inquisitor was one of the Jedi Sentinels who overheard Bariss Offee's proclamation of the failures of the Jedi Order and her words planted the seed of doubt in his heart. Unfortunately, by becoming an Inquisitor, he has joined with the very people that caused the Jedi and Republic's fall from grace.

* More recent ''Franchise/{{Transformers}}'' storylines have this happening to [[TinTyrant Megatron]]. He usually gets his start as an idealistic miner-turned-gladiator chaffing under the FantasticCasteSystem that's been crippling Cybertron, starting protests against the corrupt Autobot leadership and forming a friendship with Orion Pax, an Autobot who believes that his cause is just. Unfortunately, his own growing discontent with the system, his bloodlust, and his desire for power and the right to lead Cybertron into a new GoldenAge eventually [[YourTerroristsAreOurFreedomFighters makes him more radical]] and turns him into [[FaceHeelTurn someone just as bad as the ones he was fighting against]] as he goes to war with Orion, now his mortal enemy [[BigGood Optimus Prime]]. By the time of the present day and their conflict gets to Earth, Cybertron is a war-torn wreck and Megatron is [[BecameTheirOwnAntithesis a warmonger who will settle for nothing else than total domination of the universe, freedom the farthest thing from his mind]].

* ''VideoGame/DragonQuestIV'' has this happen to Psaro the Manslayer, who starts out thinking HumansAreTheRealMonsters due to how they treated his beloved Rose and sets out to ensure she'll never be hurt again... despite her constantly begging and pleading with him to stop. Things only get worse after [[spoiler: she's murdered by human thugs]], causing him to declare he'll simply KillEmAll. By the time the chosen ones confront him, he's used [[spoiler: the perfected Secret of Evolution]] and completely lost his mind, declaring that all he remembers is his name and his hatred of humankind.

* Chirin the lamb from ''Anime/RingingBell'' originally seeks out the wolf who killed his mother with the intent of revenge, but finds he is far too weak. Instead, he asks to become the wolf's apprentice, with the intention of killing the wolf once he's taught him all he knows. The years pass, and Chirin grows into a monstrous ram. He forgets his mother, forgets his mission, forgets he was ever a sheep at all. Its not until they eventually return to Chirins former home at the farm where the wolf wants him to kill the sheep that Chirin finally remembers. [[RedemptionRejection But by then its far too late...]]

* Bandora from ''Series/KyoryuSentaiZyuranger'' turned evil after her son was killed by a Tyrannosaurus. Eventually she went mad with power and forgot all about this until her son came BackFromTheDead. Her ''Power Rangers'' counterpart Rita Repulsa had a petty personality of pure evil, with her goal changed to her wanting to conquer the universe.

** Sasuke is a poster child for this. While he was always firstly driven by his wish to take vengeance upon his brother for murdering their family, his time in Konoha made him connect to the members of his team. The lure of revenge was too great, until he decided to break those ties. [[spoiler:[[MotiveDecay His motives have rapidly degenerated]] after joining with Madara. Initially after learning of the truth behind his brother's murder of his clan, Sasuke simply wanted revenge against the Village Elders who manipulated him. Now he won't settle for anything less than the complete genocide of anyone who lives in Konoha. There's some hints that Sasuke is being influenced by something (Madara claims the Uchiha bloodline is TheDarkSide), probably an AuthorsSavingThrow given that during the summit arc he rather suddenly turns into a cardboard villain after gaining Susanoo (amongst other things, he abandoned another set of teammates that he seemed to care about earlier, who in the previous arc had saved him from being killed)]].