Jumping Off the Slippery Slope

Jumping off the slippery slope is when a morally ambiguous character raises an ethical question by doing morally ambiguous things, but instead of answering those questions, the character closes the debate by going on to do something unquestionably and unforgivably evil.

This is a condensed form of the Slippery Slope Fallacy—instead of Sliding Down the Slippery Slope by gradually becoming more evil, they go straight from "may or may not be moral" at the top of the slope to "unquestionably evil" at the bottom, skipping all of the intermediate shades of gray—thus jumping off the slippery slope.

A form of Debate and Switch, because they never really address the question of whether the original ambiguous action was acceptable or not. Also helps to maintain the status quo by ensuring the main characters never question their own morality too closely. Compare Slowly Slipping Into Evil for a longer, more developed process of going from "ambiguous" to "evil".

Compare with Moral Event Horizon, Motive Decay, and Aesoptinium. Can be a result of a Well-Intentioned Extremist realizing that there is No Place for Me There and becoming a full-time villain. In case the characters in question were friends prior to Slope-Slipping, it probably triggers We Used to Be Friends. If the slippery slope has been greased with Phlebotinum, that's The Dark Side.

Anime & Manga

 * Masterfully avoided in Higurashi.
 * Death Note: Yagami Light begins using the supernatural notebook to rid society of criminals, but soon his black list expands to include anyone who stands in his way for any reason, starting with the FBI. Along the way, he coolly manipulates the feelings of both people and shinigami. Repeatedly stating that he plans to become the god of the new world he is trying to create doesn't help matters, either.
 * For that matter, Mikami Teru uses the notebook to eliminate minor and reformed criminals.
 * Declaring that he will eventually execute people for being lazy implies that Light has done away with the slippery slope completely and simply jumped off the metaphorical deep end.
 * And, of course, Mello joined the Mafia and killed and threatened innocents for the sole purpose of tracking down Kira.
 * Shu Ohma in Guilty Crown after
 * In Code Geass, Lelouch Lamperouge wanted to destroy the Empire of Britannia (despite being an ex-Imperial Prince) and started to organize La Résistance. However, as time passes, he becomes more hardened and crazy, going as far as
 * And of course, we have The Emperor and V.V,
 * In general, everyone in Geass flew off slippery slopes.
 * Lelouch and Suzaku are the extreme cases. As well as the others named above. Ironically,
 * There's also Nina. Who has one of these when
 * In Mobile Suit Gundam 00, the Trinity group shows up and starts actually destroying military bases and arms manufacturers. Most of the battles up until this point had hundreds of civilian casualties, with one battle threatening to basically screw the entire world with nuclear radiation. Through destroying military installations instead of waiting for war to start, Trinity is preventing these needless deaths. However, the "it's not right to attack before you're attacked" excuse is played, Trinity is painted as villainous when it's actually clearly good... and it suddenly starts blowing up random buildings for no reason. Let's also point out that the villains out to cause perpetual war for personal profit are never portrayed in nearly such a negative light.
 * While Trinity's actions may have been jumping of the slippery slope they were hardly 'clearly good' in the first place- Gundam 00 is full of Grey and Gray Morality and the point is that no one side is clearly good or clearly evil. The Trinity's actions were simply causing more needless deaths by murdering civilians in arms factories and blowing up military bases which weren't attacking anyone, simply defending their homeland. Trinity's actions are a classic example of jumping of the slippery slope by quickly resorting to overly extreme methods, and are hardly unambiguously good ones being wrongly portrayed as evil. And forgive me if I'm wrong but I can't remember anyone in the series who wanted perpetual war, well besides Ali Al-Saachez.
 * It's the difference between shooting the gun out of someone's hands and shooting their hands off so they can't wield a gun in the first place.
 * Depending on your viewpoint, Celestial Being itself was doing a lesser version of this before Trinity even showed up. They certainly had no compunctions about blowing up a training facility for Super Soldier children, and all the civilians inside, as a revenge operation.
 * Allelujah certainly had his compunctions.
 * As did the rest of Celestial Being. Halleluah, Allelujah's dark half, enjoyed it and egged him on.
 * The last two episodes of the first generation in Gundam AGE shows Flit Asuno taking the dark descent to becoming a revenge-obsessed Earth Federation fanatic.
 * The last episode of the second generation shows that It Got Worse, when Flit Honestly, the man is getting dangerously close to the Moral Event Horizon here, if he hasn't crossed it already.
 * Narrowly averted in Fullmetal Alchemist when
 * Also narrowly averted in the 2003 anime version when Ed almost uses the prisoners trapped in Lab 5 to create a philosopher's stone he's been searching for.
 * Fushigiboshi no Futagohime: Fine and Rein find out that Mirlo is in an Arranged Marriage with a rather undesirable dimwit, and are out to break it up. Reviewer Al1701 pointed out that this action seems short-sighted, since the deal for the marriage is in exchange for dimwit's father repairing the Waterdrop Kingdom's cloudmaker.
 * In Berserk, no one ever really addresses Griffith's actions, since they're so amazed at how far he's willing to go in order to achieve his dream of having his own kingdom. Even if those actions may have included, or   or  . However, the audience is shown this from a more sympathetic light, especially so after his   since he speaks of his dream so nobly and pure. And then the Eclipse happened. The audience lost all sympathy at that point.

Comic Books
"SD: "It just starts with stealing a soda after saving the store...next thing you know, you're hacking up people and putting them in your freezer!""
 * The Killing Joke is all about The Joker trying to break Commissioner Gordon. He fails.
 * The majority of heroes who meet The Punisher in the Marvel Universe are usually technical pacifists, so most of them think that this Anti-Hero has jumped off and is now gaily frolicking at the bottom. In fact, any Anti-Hero who lives in a verse that's on the idealistic side of the Sliding Scale of Idealism Versus Cynicism could be said to have jumped, at least from an in-universe perspective.
 * Averted sometimes in the Marvel Universe when he doesn't kill (for various reasons, mainly when having to team with the majority of the protagonists), and averted in his MAX series where to date things have been almost entirely on the cynical side and... Then again, arguably he's not treated that nicely there either, it's just that his targets are apparently much, much worse, and the reason that he keeps a select few alive? Well...
 * Garth Ennis admitted that his sheer anger regarding human trafficking and sex slavery led to the infamous arc "The Slavers," which has Frank Castle ... even after Frank admits that this won't make a big difference and that he's just going after their group, and at the end his inability to really help the victims.
 * In the Punisher MAX book "Born" it's pretty much stated the Punisher is a sociopath who's addicted to killing, and that if it wasn't criminals it would just be someone else. It is also sort of ambiguous as to whether he sold his soul to some sort of demonic entity, or was just going increasingly insane.
 * It's arguable how far down the slope he already was, but the arc Superman: Ending Battle is this for Manchester Black. Initially, Black was a Type IV or V antihero who managed to just hover on the line between Chaotic Neutral and Chaotic Evil, but, after he learns Superman's secret identity, he leaps across the Moral Event Horizon; 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 kill Lois Lane, all as part of a massive Thanatos Gambit to destroy Superman by goading him into breaking the One Rule . When Superman refuses, Black suffers a major Heel Realisation and telekinetically blows his own brains out.
 * Hal Jordan, who got so pissed off that the Guardians forbid him to use his ring to temporary recreate Coast City that he flew to Oa, maiming numerous other Green Lanterns in the way and stealing their rings (how did they survive the vacuum of space is unknown), killed Kilowog, killed Sinestro, absorbed the whole power of the main battery (destroying it in the process), became the villain Parallax and then 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. Of course, it was later retconned as he being possessed by the fear entity Parallax, but still...
 * Notably averted by Alan Grant's DC Universe character of 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 Batman, which makes for some nice Not So Different interactions.
 * In Superman Annual 3 in the 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.
 * Played with when Scans Daily showed a panel with Robin and the Spoiler foiling a convenience store robbery and Stephanie taking a soda. Tim assumes she's going to pay for it, while she explains that she's earned it as they saved the whole store. She grudgingly puts down some money when Tim explains that once you start like that, you soon bend all the rules.


 * To be fair to Robin, what he is saying is real-world law enforcement practice; Internal Affairs goes after cops even for accepting the most minor bribes or freebies precisely because taking them psychologically desensitizes police officers towards the idea that they 'deserve' extra-legal recompense for their sacrifices, which is for obvious reasons a train of thought they don't want people to even go near starting.
 * A German Film Stahlnetz: PSI begins with two brothers kidnapping a rich girl  for ransom. They reason a girl is a Spoiled Brat anyway and a few days in captivity won't hurt - and for her family, a million is only a pocket money, so it's not really bad. But then the younger brother decides that it is better to leave the girl to die, and.
 * In Star Wars Legacy Emperor Roan Fel is willing to use Sith powers to get his Empire back.
 * Dealt with in a two-issue arc of New X-Men 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 Emma Frost 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 Mega Corp that has developed cures for cancer and AIDS. How did he achieve this breakthrough? . 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 One World Government. And he's also . Okay, now he has to die. Fortunately.

Fan Fiction

 * Ho-oh from Poke Wars wants Pokémon-kind to live in a utopia and he limits his targets to humans only and tries limit the damage he causes.

Film

 * Yoda warns of the danger of the Dark Side, 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 in Star Wars. Specifically, note how quickly he goes from to . Anakin finally slips so far, his own wife, Padme, 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, Darth Sidious subjects him to painful body reconstruction. The final push to the Dark Side comes from Sidious himself- when Anakin asks if Padme is still alive, Sidious tells him in his anger, he killed her. In pure disbelief of this, Anakin's true powers of the Force flare up, and he screams out in despair, fully overtaken with pain and hate, completing his transformation into Darth Vader.
 * Fortunately, it was not to last. By the sixth film, it becomes evident Vader shows signs of regret when Luke challenges his motives, but Vader dismisses them and says it is too late for him- no one can leave the Dark Side. It isn't until Sidious repeatedly strikes down Luke with Force lightning that Vader finally comes to his senses and reverts back to Anakin Skywalker, slaying the Sith Lord, but at [.
 * The character of in the Saw movie series makes Jigsaw look downright merciful by the 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
 * Magnum Force has Dirty Harry dealing with cops who have been executing guilty criminals who escaped justice due to technicalities. When he refuses an offer to join them, they try to murder Harry, thus proving they didn't have a complex or unorthodox sense of justice after all, they just like killing.
 * The real Moral Event Horizon was before that when they murdered Harry's unstable friend, Officer Charlie McCoy, simply for being in the wrong place at the wrong time.
 * Crimson Tide is often noted as quite admirably morally complex for a Jerry Bruckheimer film, with Gene Hackman's character given quite a bit of sympathy in wanting to launch the missiles. At least until the ending, when he makes a thinly veiled racist comment to Denzel Washington, which Washington promptly reverses on him.
 * There's also the fact that Gene Hackman's character gets increasingly loud as the movie continues, yelling and screaming at people, while Denzel remains calm and logical, which serves to show you just who's right.
 * The Dark Knight Saga, didn't so much "jump off" as much as.
 * Sweeney Todd: The Demon Barber of Fleet Street: Sweeney Todd goes from wanting to just get revenge on two specific people to randomly murdering people off the streets who won't be missed and having them baked into pies about halfway through the movie (same thing goes for the stage version as well).
 * Major König in Enemy at the Gates might be a Punch Clock Villain or a Worthy Opponent for most of the movie. He even shows a veiled contempt for brutal goons who beat up prisoners. And then he
 * Potentially justified,
 * In Super Rainn Wilson's character decides to fight crime. This begins with trying to stop drug dealers, but turns into him brutally beating people with a monkey wrench (for cutting in line at the movie theatre).
 * Loki arguably did this in between Thor and The Avengers.
 * It may even be definite that Loki did this, seeing as his actions went from more manipulative in Thor to straight-up evil in The Avengers.

Literature

 * Oh dear Lord Jacen in Legacy of the Force. In the first book he has a vision that the galaxy will fall into chaos and he will end up killing his mentor Luke Skywalker unless he listens to the Villain of the books, and is forced to kill one of his allies who refuses to listen to Jacen's reasoning. Cut to book two when he tortures a prisoner because she knows about a plot to kill his parents and accidentally kills her. Cut then to book three where it is he who is trying to kill his parents because "My parents are terrorist scum, and that is why I have to show no mercy towards them.". This might be a clever showcasing exactly how "Falling to the Dark Side" works - turning the most justifiable cause into For the Evulz-Obviously Evil. It might also be a badly written mess.
 * In Damon Knight's short story The Analogues, a scientist invents a procedure to create a "better conscience" in the form of hallucinations that prevent you from committing crimes. This raises a lot of questions about the morality of removing free choice, but then it turns out the scientist plans to use it to take over the world, and has.
 * King Erius in Lynn Flewelling's Tamir trilogy starts by taking the throne from his insane mother, who was executing people left and right, in defiance of the divine edict that for no apparent reason essentially promises Bad Things if a man ever rules the country. Bad Things happen. He then proceeds to institute sexist practices and start killing off his female relatives...
 * Ho boy, does this ever happen in the eleventh book of Everworld to . K.A. "Ambitious, intelligent, controlling, Dangerously Genre Savvy Visionary Villain with a taste for power" into "batshit insane, power-mad, Genre Blind Bad Boss Evil Overlord."
 * In Memory, Sorrow, and Thorn, this trope in a nutshell is the Backstory of the Big Bad, the Sitha prince Ineluki. Once a purely heroic figure, his ambition and willpower darkened when the Sithi's lands were invaded by savage humans. Dismayed by his people's despair in the face of their approaching doom, he delved into Things Man Was Not Meant to Know and constructed a weapon so terrible that his father the king insisted he destroy it. Maddened by this rejection and by his torments, Ineluki murdered his father and took the crown, leading a final, futile resistance against the humans that ended in his death via Dangerous Forbidden Technique. It is deeply unfortunate for the world of Osten Ard that he did not stay dead.
 * Carrie decides to flood the school gym in order to ruin the prom. Within a few paragraphs, she decides to kill everyone instead.

Live Action TV

 * Star Trek had numerous cases of this. For example, in Star Trek: Voyager a race of holograms rebel against a race that had been hunting them, and start freeing all other holograms in the area. Even Voyager's holographic doctor joins them. But then they start killing off anyone who might enslave an intelligent hologram.
 * Then they move onto anyone who uses humanoid holograms at all, regardless as to whether those holograms are intelligent.
 * Xena: Warrior Princess had 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.
 * See also Calisto, who 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 Disproportionate Retribution, becoming increasingly less sympathetic in the process.
 * 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 swandive 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, and rapidly slides down the Anti-Hero scale. This ultimately culminates in the season finale, where he.
 * Angel: During Season 3, Wesley translates a prophecy reading "The Father Will Kill The Son". Not quite sure how to handle the situation, he.
 * Yeah, well, oops ...
 * Buffy the Vampire Slayer: in Season 6, Willow goes from  as revenge for   to trying to   the uninvolved other guys  . Then to hurting   and finally to trying to  . 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 good guy.
 * Battlestar Galactica: The "Pegasus" arc has been accused of this by some critics, with Admiral Cain taking about twenty minutes to go from merely being a hardassed martinet to ordering the rape of a pregnant woman as a Jack Bauer Interrogation Technique 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, gave Cain a Psycho Lesbian backstory to explain her excesses.
 * The betrayal of Gina didn't explain her excesses, she shot her XO in cold blood for disobeying orders in battle before she learned her lover was a Cylon. She was just that hard, which also allowed her to quite impersonally order the torture and interrogation of said Cylon. If there's a Freudian Excuse in "Razor", it's that she failed as a child to protect her little sister because she was too scared.
 * Exactly, it's very unsubtly hinted at that Cain had been this way since the fall of the Colonies, which Razor confirmed, and for that matter implied she probably had a borderline personality even before the world ended. It just took a little time and provocation for the crew of Galactica to realize she was a Complete Monster.
 * 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 the 'Black Market' episode, the leader of the organisation running it does a pretty good job of defending the need for a Black Market in the fleet. Then he talks about having child prostitutes, so
 * 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 Moral Event Horizon was.
 * Seems to happen about once a season in Doctor Who. A few notable examples;
 * In 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 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 scientist of a race of ersatz Nazis...
 * In "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.
 * In "The Unquiet Dead", gaseous beings called the Gelth need to animate human corpses to house themselves and hence survive — creepy, if not evil. 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 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 switch from pale blue to bright red and Satanic. Apparently, they were "demonic" all along, see?
 * "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.
 * The Doctor himself jumps from the top of the slope to the bottom in the last 10 or so minutes of "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.
 * It's implied in "The Runaway Bride" and more-or-less stated in "Journey's End" that the reason Doctor travels around with a companion is so that he has someone to remind him not to do this, since he can 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.
 * Holly in Slings and Arrows wants to streamline the Festival's business end and replace most of its Shakespeare with musicals. This is only marks her as a villain in the context of a show where Shakespeare is Serious Business, until she starts abusing her boyfriend and deliberately aggravating the heart problem of a board member who disagrees with her.
 * Gerak in season 9 of Stargate SG-1. At least he got a 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 Templars. Then it turns out they're just in it for the money.
 * Similar to the Magnum Force example, season two of Murder One 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 The Shield, Vic Mackey partakes in numerous criminal 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. Then, at the end of the episode, he.
 * An episode of The Commish features a Vigilante Man 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 Off on a Technicality) clubs him to death, setting the team on his case.
 * The season 8 finale of Smallville took an incredible amount of heat for various reasons, and one of them was this trope.
 * Season 9 had multiple concurrent threads of Well-Intentioned Extremism colliding into one big Self-Fulfilling prediction of doom:
 * Tess Mercer established an alliance with the Kandorians to save Earth from mankind's destructive ways but in the Bad Future,
 * Amanda Waller as the head of Checkmate employed threats, murders, and kidnappings to prepare for a coming war against the aforementioned Kandorians. Then she  cementing her status as a Fantastic Racist.
 * 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 Properly Paranoid about aliens among them.
 * Several characters in the 1998 Merlin series, but most notably Uther and Mab.
 * Likewise, in the later Merlin 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 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.
 * Fringe: Walternate originally just wanted to save his universe, even if it meant destroying a parallel universe and its inhabitants. Then he attempted to
 * An episode of MacGyver 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".

Tabletop RPG

 * Vampire: The Masquerade has an actual mechanic for this: acting like an inhuman, unprincipled bastard will make you more of an inhuman, unprincipled bastard.
 * This applies to all World of Darkness games and is a large part of the new system.
 * The old system was an aversion; the more humanity you lost, the harder it was to lose the next point, the more extreme your behavior would have to be. Only if you're determined to destroy your humanity (or your Gamemaster paves your path with Sadistic Choices,) could you slip past a certain point, but it wouldn't happen by accident.
 * Chaos in Warhammer 40,000 is grease on the Slippery Slope. As Chaos is a sentient form of The Dark Side by way of The Corruption, this trope becomes rather understandable.
 * Tau as well, when one considers that its for the greater good for sterilization policies, and special "helmets" for their bug allies.

Video Games

 * In BioShock (series),.
 * This is actually Justified--
 * By that logic, wouldn't the Psycho Serum force you to harvest the rest of the sisters Controllable Helplessness-style, if harvesting even the first two sisters is enough to give you the evil ending?
 * And yet, if he gets the same amount of ADAM from Tennenbaum, or just from rescuing four Little Sisters, he's fine. Methinks the ADAM didn't have much to do with it. Rather, it's that killing children just to get a slight power boost could easily be seen as crossing the Moral Event Horizon.
 * Let's not forget 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 ironfisted, totalitarian dictator, the exact opposite of what he set out to become.
 * And in Bioshock 2, if the player jumps off the slope
 * In Neverwinter Nights, Aribeth leaps quite quickly down the slippery slope (partially excused as Morag is messing with her brain and her intentions)
 * I interpreted it as more of her being consumed with hatred of the people she views as responsible for lover's death, combined with her being suicidal/ slightly unhinged over her own part in it.
 * Subverted in Rondo of Swords. After a very harsh "Friend or Idol?" Decision that ends up on the favor of the Idol, Serdic experiences an immediate Karmic backlash, complete with title change, power swap, and costume switch to reflect his dog shooting. While his Nakama repeatedly 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.
 * CJ and Niko from Grand Theft Auto: San Andreas and Grand Theft Auto IV, 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.
 * CJ's transformation is surprisingly gradual for a GTA game, actually. At first he's trying to protect his family and friends. Then he's manipulated into killing people, where if he doesn't, either he or his family will get killed. As the game continues, he eventually decides to kill the people who manipulated him. If you play a Pacifist Run (damn near impossible, but let's assume), then the only people CJ will kill are people that are threatening him, or people that he's threatened into killing.
 * And some people who were rude to his sister.
 * Well, Niko may seem pretty nice at the beginning of the game, but the plot 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.
 * Mega Man X 8 has.
 * It doesn't help that the whole of 's tale plays on the game's subtitle, Paradise Lost.
 * Malygos from World of Warcraft goes from a dragon who wants to rein in mortal spellcasters because he disapproves of their methods to a dangerously extreme tyrant who seems genuinely unaware that his plan to redirect and control magic has an excellent chance of destroying Azeroth.
 * Kael'thas Sunstrider's goal was originally to improve his suffering people. As time went on he began to make more and more questionable alliances, first with the naga, then the partially demonic Illidan, and finally knowingly aided the purpose of Kil'Jaeden and the Burning Legion (albeit only helping them to fight Arthas, which was an admirable goal no matter who wanted it). And then he tried to summon Kil'Jaeden so the Burning Legion can destroy Azeroth, killing his own people when they tried to stop him. What.
 * Illidan was always a self-serving Jerkass, but he had a more gentle side to him. After nearly being killed by Arthas, though, that gentle side was replaced with paranoia, insanity and a desire to crush anyone he deems as a threat, which happens to be everyone not on his side.
 * This happens every time one of his plans fails though. Logically all that needed to happen was for Malfurion to beat on him for a few minutes and Tyrande to be in danger, and he'd do the same thing he's done every other time. Switch sides to save her.
 * The Scarlet Crusade (at least those within the Monastery) can be accused of this.
 * 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 betraying more and more people, and becomes less and less concerned with the whole reason he's fighting the Undead in the first place. Eventually,  In his case his abrupt descent was exacerbated by him taking up a cursed sword that stole the soul of anyone it touched.
 * After Deathwing, the Big Bad in the Cataclysm expansion, is ultimately destroyed, the Horde and Alliance turn on each other big time. In particular,.
 * Arcturus Mengsk of StarCraft 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.
 * In Mitadake High 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.
 * In Fire Emblem: Path of Radiance, 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 would be the main antagonist, well you bet that country started being ruthless.
 * Final Fantasy VII - 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 then burns said village and sets out to destroy the world.
 * In Final Fantasy XI
 * Subverted in the Rise of the Zilart expansion as
 * So many in Dragon Age II, a game where 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
 * Both slopes were greased with phlebotinum in this case;
 * Adele in Arc Rise Fantasia jumps right off the slope and onto the crazy train the very instant she finds out that she's an Unlucky Childhood Friend, taking this trope to a terrifying degree.
 * The Protagonist from the Saints Row series gleefully leaps headfirst off of the slope, and then proceeds to nuke it. In the first game, you start off as a (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 civillian 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 (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 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 Awesome, espicially 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 savilily 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 neccesary.
 * Johnny Gat qualifies as well.

Webcomics
"Director Nero: A good way to get a decent person to do something horrible is to convince them that they're not responsible for their actions."
 * In The Order of the Stick paladin Miko Miyazaki starts out as a narrow-minded, Holier Than Thou Knight Templar who the titular Order despise and even her own comrades tend to look for excuses to send her off on missions to distant lands that keep her out of town for long periods. Then she
 * To be fair, The Order contains a known sociopath whose evilness is measured in kilonazis, and the rest often bend rules a bit. And there was lots of other evidence which could easily be misinterpreted by a certain type of mind.
 * Hinjo argues against that justification right there though: he heard all the same things she did but restrained himself from leaping to the same conclusions and abandoning the code of laws he had sworn to uphold.
 * gradually gone more and more eager to solve everything with violence and then took a jump, too. See comic #639. Though debates on whether this counts as Pay Evil Unto Evil, and whether that stops it being this trope, rage on the forums endlessly.


 * from Erfworld. Maybe. . Even Jerkass extraordinaire Stanley is horrified by what become.
 * Horrified? Really? At what point does Stanley appear to be even bothered, let alone horrified, by her request? He mulls the issue over for a bit, then refuses permission because he thinks Wanda's been "out of hand" lately and he doesn't want a decrypted caster anyway.
 * Maybe... or maybe she just wanted a chance to put Jack (her friend from the old Faq) on her side specifically, since anyone she rezzes with them has their loyalty aligned to HER not Gobwin Knob.
 * Discussed in Subnormality comic here.
 * The inspector in Chisuji. First he decided to take justice in his own hands against the criminal who killed his wife and sent his daughter in a coma; then he saw the killer's girlfriend holding said daughter's plush toy, and... snapped.
 * Eridan in Homestuck was introduced as a Butt Monkey Ineffectual Sympathetic Villain Jerk with a Heart of Gold, but some of his later appearances have shown that This is not foreshadowed whatsoever.
 * Schlock Mercenary has Petey using an opportunity to collect first-hand information on how step-by-step changes work.
 * Schlock Mercenary has Petey using an opportunity to collect first-hand information on how step-by-step changes work.

Western Animation

 * The Batman: The Animated Series episode "Lock-Up" introduced Lyle Bolton, ruthless head of security at Arkham Asylum, who eventually goes crazy and becomes the supervillain Lock-Up. He starts off making some good points about his regime bringing Arkham's role as a Cardboard Prison to a halt. Fortunately - so to speak - he also turns out to be a sadistic monster who steps way past his boundaries, abuses his inmates, and eventually starts locking up politicians and media members, blaming them for allowing crime to run rampant in the first place, allowing Batman to take him down without any worries.
 * When new-vigilante-in-town The Judge shows up later on, attacking the villains and not caring whether or not he kills them, this is never even brought up. It is taken for granted that his actions are wrong, which (given the long, horrible careers of Batman's rogues gallery) seems like it would be open to debate here. The big jump probably comes moments before Batman intervenes, when he is about to kill a small-time corrupt politician who had helped him, but still. How extreme can he really get, he tried to kill Two-Face in his own escape room, the catch
 * Also, in Justice League, Cadmus. Their stated goals: Provide America (and her allies, probably) a defense against the super powered types, especially the Justice League. What with Superman nearly taking over the world when being brainwashed by Darkseid, the Justice Lords in a parallel universe taking everything over, and the Justice League having an Orbital Superweapon pointing down, this seems entirely okay. Up until the cloning, torture, firing nuclear weapons, being allied with Luthor, creating Doomsday...
 * What made Cadmus utterly irredeemable was finding out that
 * There is also the fact they tried to blow up the Watchtower before the League had ever done any harm, and that Gen. Eiling was willing to a nuke an island to "kill three birds with one stone," i.e kill both Superman and Doomsday and stop the drug smuggling that came through it. Granted, only Eiling was behind this, and Amanda Waller is furious as soon as she finds out about the nuclear air strike.
 * And the Justice Lords from a parallel Earth. Superman abandoning Thou Shalt Not Kill to stop Luthor from starting a nuclear war: justifiable. The entire team doing away with the concept of Joker Immunity altogether and resorting to killing and lobotomizing on a semi-frequent basis: arguable. Setting up a totalitarian state in which elections do not happen until the Justice Lords say they do and people can be arrested for complaining too loudly: seems unnecessary.
 * And for that matter, Doctor Destiny's origin story in "Just a Dream". At first, he seems to be a fairly decent guy whose big mistake was simply getting hired as a guard by Lex Luthor, and the story starts raising questions about What Measure Is a Mook? and the hypocrisy of the henchmen going to prison and having their lives ruined while the villains themselves keep getting away scott-free. But once he gains superpowers himself, his Roaring Rampage of Revenge throws him right off the slippery slope, and into Complete Monster territory that even Lex never touched, with lemming-like gusto.
 * Not quite; the opening dream sequence of the episode shows us that Destiny always wanted to be a master villain, crushing all who opposed him and taking whatever he wanted -- its just that until he gained superpowers, he never had the opportunity to.
 * Avatar: The Last Airbender gives us Jet, whose goal it is to protect children like himself orphaned by the war mongering Fire Nation and to fight back. However, it's made pretty clear that Jet has jumped off this slope when he attempts to . He notably later attempts to jump back on the slope, but it 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.
 * It seemed like he didn't really regret his actions per se, more that he realized maybe he was going too far and started trying to rely on his team to keep him from sliding. But when he KNOWS there are Fire Benders hiding in plain sight within the city, he still just can't let it go.
 * This is what leads to
 * From the Sequel Series, The Legend of Korra, Tarrlok starts out as a Jerkass and manipulative self-serving politician. Then he goes completely off the deep end

Real Life

 * If Real Life examples are accounted for, then LG is doing this at this very moment. When a Blu-Ray license consortium was formed, LG refused to join just so it could continue to litigate against perceived patent infringements of BluRay-related patents. All part of its plan to hold an illegal monopoly on the BluRay industry, of course.
 * Alternative Character Interpretation LG refused to join an illegal trust so as to litigate their legal monopoly derived from their patent rights.
 * There was a time when Robespierre was an ardent anti-capital punishment activist who was fighting the really obvious injustices of his time. His rule would later be called The Reign of Terror.
 * Subverted- He knew what he was doing was immoral, but he did what he had to. Your Mileage May Vary.