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Compressed Vice

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Bender: It's just... neither of us can get up when we get knocked on our back.
Fry: What? I've seen you get up off your back tons of times.
Bender: Those times I was slightly on my side.
Futurama, "Crimes of the Hot"

The plotline has a character display some vice, flaw, prejudice, addiction or other negative attribute or behavior, which said character has never before this point shown any signs of suffering from, but which they then engage in solely as the setup for some sort of One Shot gag or An Aesop. (In some cases, the plot claims/suggests that they've always had this problem, even though previous episodes show otherwise.) It then vanishes totally after the end of the gag and/or plot. Sometimes this is meant to serve as Character Development, but due to the entire process being constrained to that one single episode, it's not very convincingnote . If the creators are more consistent about the issue, it becomes a largely Informed Flaw which drives several distinct episodes but still is never observed in a character outside them. Shows up frequently in Very Special Episode, although rarely in the Too Smart for Strangers variant for obvious reasons...

This is distinct from writers adding enduring flaws to a Flat Character, or hypocrisy no one notices. If the character has to try to lose the vice in the same episode, they'll find Cold Turkeys Are Everywhere (but will usually not get "Flowers for Algernon" Syndrome afterwards).

Compare Compressed Abstinence, Long-Lost Uncle Aesop, Can't Get Away with Nuthin', Characterization Marches On, Jerkass Ball, Idiot Ball, Temporarily Exaggerated Trait.

This trope is a sub-trope of Backstory of the Day.


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    Anime and Manga 
  • ×××HOLiC manages to give a Compressed Vice to a character who only appears in two episodes. After Watanuki manages to help convince a shy girl that her negativity is cursing her to fail and that she should try to be more positive, her more upbeat and outgoing twin suddenly turns into the sister from hell, psyching her out even worse than she ever did to herself until the poor girl is on her knees and paralyzed by the feelings of uselessness her sister is laying on her. Then, after Yuuko intervenes and the lessons are learned, all is sunshine again.
  • Himitsu no Akko-chan, the original 1969 series, manages to wish a Compressed Vice to the main character, just to scare her into her personal Aesop. In episode 32, aptly named "_____", upon meeting a deaf-mute kid, Akko-chan, out of empathy and curiosity, wishes to her magic mirror to be a deaf-mute version of herself. Upon discovering that, being speechless, she can't wish anymore, and she'll be stuck that way forever, Akko-chan breaks apart, feeling scared and useless until the mirror, reasoning that she got her Aesop about hasty wishes and physical ailments, and she understood the true courage of her new friend (who will never be seen around for the rest of the series), lifts the wish on its own accord.
  • On more than one occasion in the Pokémon: The Series, Ash has gotten so full of himself specifically to get a Break the Haughty moment by the end of the episode, and then go back to being a reasonably humble trainer afterwards. Instances of this include his battles with Prima, Brawley, and Drake of the Elite Four. May also got this in one of her contests when she gained a Coordinator Superiority Complex out of nowhere and was reprimanded for it, and then it never comes up again.
  • The original Japanese version of Digimon Adventure 02 gave Hikari a crippling reliance on her brother in the infamous Dark Ocean episode. It may have been an attempt to keep her from looking too perfect, but while she does freak out at the Dark Ocean in a later episode, she doesn't mention Taichi at all.
  • In the "Fake Jack Atlas" episodes of Yu-Gi-Oh! 5Ds, Jack suddenly develops a reckless refusal to play any kind of defensive strategies or cards. This is in spite of him having been quite happy to play defensively in prior seasons, even lecturing Yusei about how he enjoys being the one to be chased.
  • Louise in The Familiar of Zero went through a rapid descent into gambling addiction while trying to go undercover. Despite Saito's best attempts to stop her, she wagered larger and larger amounts until she finally placed all of their remaining funds on one bet, all without winning a single time.
  • An Arc Villain in JoJo's Bizarre Adventure: Diamond is Unbreakable has a Stand that lets him trap people in paper if he exposes their nervous tic. Josuke's tic, biting his bottom lip, appears all of once, where he does it and it gets him captured, despite being nervous several times before and after. This is only the case in the manga, however, as the anime adaptation adds additional moments in previous fights where he can be seen biting his lip.
  • While Ash did have a bit of an ego in earlier seasons of Pokémon: The Series, it tended to only get out of hand, or show up at all in later season, just in time for an episode dedicated to smacking him off a pedestal he suddenly started putting himself on.

    Comic Books 
  • The infamous Batman: Fortunate Son had Batman be given a hatred for rock and roll and punk rock that never appears anywhere else in the books before or after. Of course, while it was never referenced again in the comics Linkara and other fans will make him Never Live It Down.
  • In Blackhawk #240 (which is towards the end of the New Blackhawk Era), André Blanc-Dumont has been given a crippling fear of beautiful women. He declares himself cured after punching out a man disguised as a woman. Click here for an in-depth recap.
  • Many authors who worked on Iron Man gave Tony Stark's alcoholism a spin of their own, thus making him a borderline example. This trope applies largely because it is always restricted to specific plotlines. Outside these plots, he may be seen drinking but is never shown having this habit as a problem. Nevertheless, he is somewhat well known for this aspect of his character and there's no guarantee he won't go on a drinking binge again whenever someone decides they can make an innovative take on it.
  • In the early '90s, the Spider-Man comics had an infamous period where Mary Jane revealed right out of the blue that she used to be a smoker and a bunch of different stressful events all happening at once (such as Harry Osborn reverting back to his Green Goblin personality and the arrival of Carnage) caused her to have a relapse and take it up again. It lasted for roughly a year and a half or so before Peter was able to get her to drop the habit, and true to this trope, was never brought up again after.

    Comic Strip 

    Fan Works 

    Film - Animation 
  • In Madagascar: Escape 2 Africa, Melman the giraffe suddenly develops deep feelings for Gloria the hippo. Nothing of the sort was mentioned in the first film. A flashback at the beginning of the second film shows that, even as children, Melman had a crush on Gloria. This is partly due to the fact that a dropped subplot for the first film would've been that Gloria would've been pregnant during the film and Melman, whose crush on her was clear in this version, would've eventually gotten together with Gloria and agree to raise the child with her. Additionally, an inverse case with Melman's hypochondria in the first film, which is completely gone by the sequel. The only hint appears to be his great knowledge of medicine.
  • The Princess and the Frog does this within a single film. The realtors are portrayed as perfectly nice gentlemen until the costume party scene, where they reveal to Tiana that she's been outbid for her planned restaurant, where one of them notes that, "given [her] background, you're probably better off where you're at." The implied racism and sexism comes out of nowhere and is never brought up as a theme in the film again aside of a flashback of the exact same scene.

    Film - Live Action 
  • In Back to the Future Part II, Marty McFly develops a problem with not being able to handle people thinking of him as a coward, something that was not evident in the first film. This gets used for an Aesop about not caring what people think of you. Also a rare example where the sudden character flaw is kept: Marty didn't learn his "lesson" until the end of the third film. This might be justified by the Delayed Ripple Effect from changes to the timeline in the first movie; Part 2 Marty had a very different childhood than Part 1 Marty.
  • The Avengers (2012) has Loki calling Black Widow a "mewling quim" and displaying Straw Misogynist tendencies that were never there in the first Thor - and would seem at odds with the fact that he grew up closer to his mother. He doesn't show this trait in any of the subsequent films either.
  • One common criticism of Star Trek VI: The Undiscovered Country is the view that Kirk's prejudice against Klingons never really existed prior to that movie, in which it's contrived just so that he can overcome it. Sure, he fought against them a lot, but they were always the aggressors. Consider that much of Kirk's antipathy for the Klingons is said to stem from the fact that they murdered his son back in Star Trek III: The Search for Spock. However, Star Trek III featured a scene in which the Klingon directly responsible for that was falling into a lava pit, and Kirk's immediate response was to try to Save the Villain. And yet, three films later, Kirk hates all Klingons due to the actions of a guy whom he was willing to save? Moreover, in Star Trek V: The Final Frontier, Kirk seemed willing to accept the Klingons when they approached him in a spirit of peace.

  • A staple of The Berenstain Bears; each book usually had Brother and/or Sister (sometimes Papa too) engaging in some kind of immoral or unhealthy behavior such as lying, eating junk food, fighting, teasing, etc. They never exhibited the behavior before and after the book ends, it's never brought up again.
  • Roys Bedoys: In “What’s That Smell, Roys Bedoys?”, Roys has to learn to brush his teeth before bed, despite never having that problem in previous stories.

    Live-Action TV 
  • Alice (1976):
    • In "Block Those Kicks", Alice, Vera, and Flo suddenly gain addictions to chocolate, smoking, and coffee respectively, and, along with any mention of them, vanish as soon as the episode is over.
    • In the final season, "Tommy's Last Weekend", it turns out Tommy's quickly turned into a drunk who's suffering been suffering blackouts, loses a car, and can no longer keep up on his college courses. Tommy promises to seek treatment, which must have worked (and how!), because he's back to normal the next episode he appears. Must have gone cold turkey.
  • An episode of The Big Bang Theory had Leonard making up a lie to avoid seeing Penny sing due to her singing being Hollywood Tone-Deaf. However, other episodes have shown her singing "Soft Kitty" to Sheldon while sounding completely normal.
  • An episode of The Golden Girls revealed that Rose has been addicted to prescription strength pain-killers for decades. It also strongly implied that her perpetually sweet disposition is at least partially the result of taking these drugs. Despite the coda of the episode having her statement that she'll be fighting this addiction the rest of her life (albeit filled with hope that she can pull it off), it's never truly referred to again. Similar events happened to Dorothy, who had two relapses of former addictions she had beaten (smoking and gambling.) Aside from the episodes in question, they were never mentioned again.
  • Joey from Blossom hates a gay guy in one episode, revealing a prejudice that hadn't previously been mentioned in the show. Later in that episode, his black sister-in-law tells him a story about how she faced discrimination as a child, causing him to renounce his prejudice as quickly as he developed it.
  • A particularly offensive episode of Lizzie McGuire featured her pal Miranda becoming anorexic and then getting over it within the course of a week. It also had Gordo becoming addicted to Deeandeeaproximine... and then getting over it within the course of a week.
  • An episode of The Facts of Life has Sue Ann getting, and recovering from, anorexia.
  • D.J. became worried about her weight in an episode of Full House. She didn't eat for three days straight and was over-exercising. Danny helped her realize that her crash-dieting can eventually lead to developing an eating disorder.
  • An episode of Spin City had Carter trying to quit smoking, despite having never been seen touching tobacco before (or since). This episode also featured Paul getting addicted to nicotine gum.
  • Ned's Declassified School Survival Guide, "Guide to School Records" — Ned is a well-intentioned, "smart but lazy" kid in the rest of the series, but this episode shows him pulling all sorts of deliberately mean pranks on his way to accruing the biggest permanent record in the school. Flashbacks are used, which (unusually for the show) were filmed just for this episode, not taken from earlier ones, further playing up the trope.
  • If a young attractive female character is introduced to a series and some fuss is made over the "fact" that she smokes, then it is near certain that that will be the last time that she is seen with tobacco, or that it will even be mentioned. Examples:
    • Lois Lane in Smallville.
    • Mimi Clark in Jericho (2006).
    • Marissa Taylor in the defunct Australian comedy/drama Always Greener. Admittedly this last one could be regarded as just a set-up for a joke about an exploding cow, but credibility was stretched in a later episode where she stood right next to another character who was smoking, without batting an eyelid.
    • Gia from Full House though a later episode has her mother Claire saying Gia quit smoking after she became friends with Stephanie.
  • A particularly extreme example appeared on Rome, with the reveal that Octavian was deeply in love with (as in, wanted to have sex with) his own sister. Not only had nothing even hinting about this ever come up before, but the episode itself has zero hints about it until Servilia lets his sister know — which actually justifies it, as he was clearly very good at keeping it secret.
  • Friends:
    • In "TOW The Thumb". When the others berate Chandler for his smoking, he rattles off a list of their annoying habits that he puts up with, such as Joey's knuckle-cracking, Phoebe chewing her hair and Monica snorting when she laughs. None of them ever came up before (though this is understandable since it's only the third episode) or after. The cracks about Ross over-pronouncing words and Rachel screwing up drink orders at work don't apply as both remain character traits beyond that episode.
    • An episode that shows less respect for continuity comes in the Season Five New Year's episode where Rachel suddenly turns into a gossip who can't shut up about her coworkers' dirty laundry. The whole thing turns out to be a plot device to launch us into a Cold Turkeys Are Everywhere plot as Rachel resolves to stop gossiping, and then immediately discovers the unkeepable secret that Chandler and Monica are doin' it.
    • Several episodes made jokes about Chandler being more emotional than the other guys, and "The One With All The Candy" specifically pointed him out as the most likely to cry (and he did). Then, in "The One Where Chandler Can't Cry" it turns out...
  • Done in Red Dwarf where the crew is forced through the air ducts of Starbug. Lister is revealed to have claustrophobia. Subverted somewhat when Cat lists a number of examples where he's been trapped in a confined space and didn't freak out; naturally, this didn't help Lister.
  • Star Trek: The Next Generation: Worf was the victim of this in the episode where a genderless alien species showed up, and he was saying things like it being "unnatural" and the like. This particular prejudice wasn't seen previously in all the cases where he met aliens who didn't have a traditional gender setup and never appeared again.
  • Star Trek: Deep Space Nine:
    • When Odo becomes involved with the Female Changeling in "Behind the Lines" and "Favor the Bold," he becomes utterly obsessed with linking. Given that their linking scenes have the feel of love scenes, and that he neglects other duties to link with her, his actions seem to be a metaphor for sex addiction. This was merely a rare lapse in Odo's normal ability to keep his emotions closely guarded. Several episodes mention or deal with how important Linking is to him and his species, and how much it's the thing he's most forsaking in order to reject The Founder's actions.
    • There was a late episode, where there was a homicidal shapeshifter on the station, and the other main characters responded by revealing their prejudice against shapeshifters, which had never been hinted at before, even after years of fighting a Dominion run by shapeshifters. Might have been partly explained by that particular shapeshifter constantly harping about how everyone else was prejudiced against him for being so superior to them (which inclined them to treat him like a jerk). Odo's friends make an effort to be nice to the stand-offish stranger at first, but he brushes them off and accuses them of trying to make Odo an Uncle Tom.
  • Similar example in Star Trek: Voyager, in an episode where the Doctor found out that Janeway had tampered with his memories to prevent him going "insane" over an old triage case, and Janeway and the entire crew suddenly seemed to develop an anti-AI prejudice which then immediately vanished again next episode. This is made worse in hindsight because another episode had them arguing the Doctor was a person, not just an AI, when he was denied rights over the publishing of his holonovel for being a hologram.
    • A further example occurs in a Voyager episode where Chakotay notes that whenever Janeway fiddles with her comm badge it is a tell-tale sign that she's making a big plan. Janeway then performs the incredibly awkward-looking gesture, which she never did before or after that one moment.
  • Happens all the time in Degrassi, largely as a result of Executive Meddling. The creators of the show initially wanted to portray vices more realistically, but CTV, considering Degrassi to be an educational show, forced them to make every Very Special Episode show a compressed vice, allowing younger viewers to see the moral quickly, Once the show switched channels, they began portraying vices more realistically (examples: Fiona is shown to be drinking excessively for a large part of the season before being revealed as an alcoholic, Cam is shown to be suffering from depression and anxiety before committing suicide, and Katie pops pain pills for several episodes before being sent to rehab).
  • Vampire's strong vulnerability to werewolf blood in Being Human (UK) Wasn't heard of and only revealed very offhandedly several series in.
  • Tommy from 3rd Rock from the Sun is revealed in one episode to have been hiding sandwich bags full of spices to indulge his secret cooking hobby in secret. "It's marijuana. I smoke it with friends I swear!" This is never mentioned again.
  • M*A*S*H: Winchester falls to the temptation to taking amphetamines, and quickly pays the price becoming addicted to them.
  • Likewise Commander Straker in the UFO (1970) episode "Sub-Smash". He develops claustrophobia on a submarine despite operating numerous times in spacecraft which should give him similar problems.
  • The Professionals: In "Klansmen" Bodie displays overt racist behaviour never shown previously by his character; it's not that such tendencies would be unusual in that era, especially from a decidedly working-class bloke like Bodie, but it was completely out of left-field and due to the events of the episode (in which his life is saved by a black doctor) we never see it again. Actor Lewis Collins was not pleased.
  • Subverted in Malcolm in the Middle. Francis claims to have successfully completed AA despite never having been shown getting drunk in previous episodes. It turns out that Francis is so desperate to blame his problems on something other than himself that he convinced himself he was an alcoholic.
  • Baywatch was rather terrible with this. Depending on the Writer, characters would suddenly have eating disorders, gambling addictions, PTSD from previously-unmentioned past traumas, and numerous other personal issues that would immediately disappear by the next episode.
  • How I Met Your Mother
    • An episode deals with the annoying habits of the group. The bad habits of Ted, Marshall, Barney, and Robin are noticeable prior to the episode (although Robin's misuse of the word was subtle before it was pointed out), and they still have them in later episodes. Lily's habit of chewing too loudly is a true Compressed Vice, as it appeared only for that episode. Justified in later episodes featuring the characters throwing "interventions" to stop each other's similar minor annoying habits: though Barney's use of magic was featured in previous episodes, other characters' habits had just never been incorporated into Future Ted's unreliable narration.
    • Lily is a frequent victim of this. One episode gave her a complete inability to aim just because the episode was about the group's blind spots in regards to common knowledge (something that doesn't even follow the main theme anyway...), and another episode claimed she had many similarities to Marshall's father just because the episode was about the psychological tendency to end up with someone like your parents.
    • Another episode shows all five characters being habitual cigarette smokers. Previously, Barney, Robin, and Lily had been seen smoking cigars, and it was hinted that Robin smoked cigarettes, but this episode portrayed Robin as practically a chimney. The other characters don't smoke nearly as often but obviously way more than has ever been let on before. Ted's children are stunned at the news. Justified, as Future Ted on-occasion realizes he forgot to mention seemingly-obvious plot points until they became relevant to the story. He's also actively editing content, most notably with his "eating sandwiches" euphemism.
  • Saved by the Bell:
    • Jessie Spano's one-episode caffeine pill addiction. It does at least tie into her being an overachiever.
    • One episode has Lisa claiming she's a stress eater, who's gobbling snacks over fear about a difficult history test. This never shows up again.
  • In the Lent episode of Father Ted, while Ted's smoking and Jack's drinking have been previously established, Father Dougal's addiction to rollerblading only exists in this episode. However, as the whole series runs on Negative Continuity and Rule of Funny, this scarcely seems to matter.
  • An odd example from 24 in that Jack's heroin addiction from season three is dealt with over multiple episodes, but since those episodes take place over one day, he really should be suffering for far more than the first few hours. But then, many examples can be taken from the show where people get over things (emotionally or physically) way faster than they should realistically be able to — Tony having major surgery after being shot but getting straight back to work just a couple of hours later, for example. The heroin thing was handwaved by Jack being given some vague other drug that would mask the withdrawal symptoms for about a day, i.e. the rest of the season, after the writers realized it was becoming more trouble than it was worth.
  • Eri in Tensou Sentai Goseiger is revealed to be very messy and lazy in Epic 9, causing her to clash with Moune as part of their focus episode. These bad habits are never mentioned before or since.
  • Glee:
    • In "The Power of Madonna", the boys are suddenly shown mistreating the girls in various ways in order to set up the feminist message of the episode. This is incredibly jarring because, for instance, Artie is shown being rude and misogynistic to Tina, even though he has never displayed this attitude before (though he would display it again in the future).
    • A few other examples include Mercedes developing a borderline eating disorder (cured by a granola bar and a "Don't worry, you're beautiful" talk), Rachel becoming self-conscious about her big nose (cured by a song and dance number), everyone becoming a heavy drinker (cured by solemn talk from Mr. Schue) and Tina all of a sudden being jealous of Rachel (cured when she's promised solos next year, which incidentally never happens).
    • Ryder is suddenly revealed to have crippling dyslexia. It isn't cured or mentioned again and he's able to read perfectly in a later season.
    • At the beginning of Puppet Master Blaine inexplicably becomes an insufferable control freak, which is then promptly cured by the end of the episode.
    • The latter seasons in general tended to make excessive use of this to compensate for the increasingly thin overarching story-lines.
      • Rachel learned every other episode either that she shouldn't apologize for the ambition or that sometimes friendship is more important than ambition, Depending on the Writer.
      • Sue learns not to be a psychopath and that the Glee club is not so bad a few times per season.
      • Shue learns not to impose himself too much on the Glee club a little more often than necessary.
      • Santana and Quinn learn to be kind
      • Finn and Puck (and to a lesser extent the cheerleaders) also constantly learn that popularity isn't everything
  • Stumpy's gambling addiction isn't mentioned at all in season one of Carnivàle, even though by the beginning of the second series he has the debt collectors after him and a $400 debt (in old-timey Great Depression-era money). Adjusted for inflation, $400 in 1934 would be worth about $6443.73 in 2010's dollars.
  • In one Very Special Episode of Boy Meets World, Shawn gets drunk for the first time and then has a drinking problem for about a week before his friends convince him to give up drinking altogether. However, he does turn back to alcohol in an episode two seasons later after he learns some devastating news, though only for that episode.
  • In one episode of Alice, Alice, Flo, and Vera all try to help each other kick their previously-unmentioned vices: Alice eats too many sweets, Flo drinks too much coffee, and Vera very uncharacteristically smokes. None of these vices, or the fact that at the end of the episode, they had all switched vices, was ever mentioned again.
  • In the Community episode "Regional Holiday Music", Glee Club instructor Mr. Rad insists that Britta play the part of a mute tree, and when we finally see Britta sing her awkward song, we understand why — she's terrible. Thing is, we've heard Britta sing in other episodes. We hear Britta sing in the very next scene. She's not terrible at all unless the plot requires it.
  • The Mary Tyler Moore Show episode "Mary's Insomnia" has Mary turn to sleeping pills to get over a newfound case of insomnia, becoming dependent on them, and getting over her addiction, all within one 25-minute episode.
  • CeCe Jones in one episode of Shake it Up is revealed to be dyslexic. Although she is portrayed throughout as Book Dumb, the dyslexia is never mentioned again. This is an Actor Allusion since Bella Thorne suffers from this in Real Life.
  • House of Anubis: In season 2 Sibuna all admit that they have phobias that make it hard to get through one of the tasks. These phobias came out of nowhere and were fixed pretty quickly. Alfie's phobia, (Claustrophobia) at least, was mentioned again in season 3, and Amber's bug phobia was mentioned in passing earlier on. But the rest of them? Never mentioned again.
  • In an episode of Mama's Family, Thelma Harper becomes addicted to the local home shopping network and starts filling the house with useless stuff. After failing to make her stop, the rest of the family comes up with an idea: They agree to watch the shopping show with her, and whenever she tries to buy something, scream "NO!" and hit her over the head (they got the idea from a pet-training guide). It works, as the home shopping bug doesn't come up in any following episodes.
  • Frasier: Happens to Niles a few times. One episode sees him become obsessed with one of his nephew Freddy's videogames; another has him develop a fast food addiction. Neither of these addictions were brought up previously because he'd never been exposed to either before the episode in question,note  but they still never get mentioned again afterwards.
  • A Very Special Episode of Hannah Montana reveals that Oliver Oken has Type 1 diabetes and cannot eat sugar. The issue is never mentioned again after the episode. The episode in question was a rewrite of a previous unaired diabetes-centered episode criticized in test screenings by medical professionals for getting various facts wrong about the condition.
  • Happens frequently in 30 Rock, usually to Liz or Jack's current season's love interest. A notable example in Dr. Drew Baird, who gives all the outward signs of being a fairly normal, competent pediatrician is suddenly Too Dumb to Live.
  • Frontier Circus: In "Dr. Sam", Casey displays levels of chauvinism he never showed before or after, simply to drive the plot about a female doctor wanting to join the circus.
  • Justified on iZombie: Zombies temporarily take on traits of the people whose brains they eat. We've seen Liv become racist or a compulsive gambler or a stalker for an episode because the Victim of the Week had those traits.
  • The Bradys, one of the Brady Bunch Spin-Offs, had Marcia begin drinking, become a full-blown alcoholic, come to a crisis, and enter recovery, all in one episode.
  • The Victorious episode "Jade Gets Crushed" has Andre develop feelings for Jade, which makes him uncomfortable because she's dating his best friend Beck. Despite spending much of the episode obsessing about this, he gets over her pretty quickly at the end of the episode to go chase another girl. These feelings aren't really brought up again, even after Jade and Beck break up.
  • An episode of Henry Danger has Henry tell Charlotte that she can't be a superhero because she's a girl, despite not showing this attitude towards her before. The show tries to justify this by suggesting Henry only feels this way because he's worried about Charlotte taking his job as Captain Man's sidekick. However, the subplot of Charlotte becoming Captain Man's new sidekick is quietly resolved at the end of the episode, making Henry's sudden sexism subplot pointless.
  • Seinfeld:
  • The Brothers García:
    • "Larry's Curse" makes Lorena out to be naturally clumsy. She trips while carrying some tea to one of Sonia's clients, and can't walk with books on her head without falling after a few minutes. May be somewhat justified since Larry believes breaking a good luck charm has resulted in sudden bad luck, but also extremely coincidental with Ray's Golden Moment about how there's no such thing as luck (since Lorena's clumsiness vanishes after this episode).
    • Another Lorena one in "You Go Girl". She suddenly becomes passionate about gender equality and being included, with Sonia having a realization about gender imbalances in the family. Ray in particular suddenly acts rather chauvinistically, treating the housework as something entirely for Sonia to do. Lorena was never not included in the brothers' schemes and if she wasn't, it was because of her constant snitching on them rather than because she was a girl. Could possibly be hand waved as something she spontaneously picked up from reading a magazine.
  • Odd Squad:
    • The conflict of "Recipe for Disaster" is driven by Olive and Otto being on bad terms with each other and seeing each other in a negative light — Olive thinks Otto is too immature and laid-back, while Otto thinks Olive takes things far too seriously. This is despite the fact that their partner chemistry is strong and they're never shown having a full-blown argument even once throughout the season.
    • In "Flatastrophe", Oprah becomes quite vain when Otto takes her six pieces of artwork (a Shout-Out to "Marilyn Diptych") and she complains that she has nothing beautiful to look at before holding up a mirror and looking at her reflection. While she does hold herself in high standards, it's not usually to It's All About Me degrees.
    • Another Oprah-related example occurs in "Not So Splash" where the driving force of the episode is her treating swimming as an emotional crutch for her and getting upset enough to give Implied Death Threats to Olive and Otto when she tells them what will happen if she is unable to swim.
    • In "Odd Squad Needs You", Oscar is shown being fearful of Oprah when Otis offers to make the titular commercial with her as the lead actress, because in his own words, "You can't boss the boss!" While he does display fear and surprise at Oprah's actions at times, it's usually subtle, and it never goes to such an extent that he hides to get away from her and her presumed wrath like in the episode.
    • In "Running on Empty", Omar, who is already well-known as The Ditz, decides to take hold of the Idiot Ball and become even more stupid than he is originally, prioritizing playing games with Oswald to get to know him better over catching a blob. He's never shown to be this dumb in any future episode.
    • This trope ends up being one of the major flaws in the Story Arc for the first half of Season 3. In "End of the Road", it's revealed that Opal was too overprotective of Olizabeth, and because of it, she dropped out of the Academy and became a villain instead while Opal graduated and became an agent. However, Opal has never displayed such a trait throughout the season, and while she does show concern for her teammates' safety at times, it's never taken to Safety Worst extremes.
    • In "Nature of the Sandbeast", Orla develops an inflated ego when telling her story of how Dr. Dry got the titular Sandbeast's golden egg. While she is known to be smug at times, she usually resorts to Brutal Honesty rather than egotism.
  • Young Sheldon: In "A Therapist, a Comic Book, and a Breakfast Sausage", Sheldon develops a phobia of solid food after choking on a sausage. It only lasts until the end of the episode, when his discovery of X-Men comics gives him the courage to face his fear.
  • It's a Big Big World: Madge in "Take Care Of Yourself." She starts the episode doing her daily exercises, but in the middle of a squat, she pauses to address the viewer and finds she can’t rise back into a standing position. Luckily, Burdette gives her a little lift and the two discuss safe exercise techniques, and fortunately Madge is able to finish her exercises after resting up.
  • One Life to Live's Max Holden visited a casino on Valentine's Day. 4 months later, he was a full-blown gambling addict who'd walked out on his wife of 6 months and begun an affair with the ex-girlfriend who was enabling him. Then, following an accident in which his wife was injured, he finally had a Heel Realization about his behavior and sought help, recovering in time for he and his wife to reconcile and her to announce her pregnancy on Christmas Eve. After this, his addiction was never referenced again.

    Video Games 
  • In Year 2 of Grim Fandango, Manny's driver/sidekick Glottis is suddenly revealed to have a gambling problem when Manny offers him a VIP membership at the cat track. It's implied that cat racing is an outlet for Glottis's obsession with speed.
  • Moshi Monsters: One of the magazines listed Whurley as being afraid of heights, but he's been up high in the mission "Strangeglove From Above" and not been scared.
  • In Pokémon Mystery Dungeon: Rescue Team, the partner Pokémon briefly displays cowardice when Jumpluff tells them and the player about the scary monster supposedly living in Silent Chasm. The partner fakes a stomach ache in an attempt to get out of the mission, and gets comically upset if you don't play along. Until then, they'd been been shown as a friendly and dedicated Pokémon. Shortly afterwards, the player has the option to fake a stomach ache when Alakazam explains more about Zapdos (the "scary monster" in question), at which point the partner will say that their friend does this "all the time" and it's really embarassing.
  • In Barkley, Shut Up and Jam: Gaiden near the end each member of the party are put through a Secret Test of Character where they are faced with a personal temptation. While the other party members manage to overcome the test Barkley ends up succumbing to his never-before mentioned desire for Incan Gold.

  • Inverted and possibly subverted in the webcomic Narbonic, where Dave's chain-smoking habit is established early on and continually referenced. However, after Dave goes back in time and alters the event that causes him to start smoking, he is surprised to find that he has no addiction at all... and the other characters assure him he never did, smoking was never relevant to any of their adventures, and they are confused when he brings it up. The author even devotes a filler comic to two fans explaining how the previous plots where his habit was a key point make sense without it.
  • Subverted in Unshelved. A storyline deals with Colleen quitting smoking — when there was no indication of her being a smoker before, and the other characters are surprised to hear about it. At the end of the storyline, it turns out this is because she quit decades ago when she was still a teenager — she made it sound current as an excuse for being rude to a patron at the library.

    Web Original 

    Western Animation 
  • 101 Dalmatians: The Series: In "Cruella World", Lucky is said to have the habit of constantly stretching the truth, making it so that nobody believes him when he tries to tell them about Cruella's latest evil scheme. Despite the fact that everyone treats this as an established trait of Lucky's, with all the animals already distrusting any of Lucky's stories at the start of the episode, he's never seen embellishing his stories in any other episode, and he's never had any issue of anybody not believing his stories, especially when they concern Cruella.
  • Adventure Time:
    • Finn falls into the dark, foul abyss that is shipping addiction in "All the Little People". While it only lasts an episode, there's a FOUR MONTH Time Skip in the middle, in which Jake moves out after finding Finn's behavior creepy.
    • "Power Animal" gives Jake extreme ADHD. He has shown a short attention span in other episodes, but never to the absurd life-threatening levels shown here.
    • One episode has Jake ignore Finn because he's supposedly always making up fake adventures. Whether the Compressed Vice is Finn's (for lying) or Jake's (for disbelieving Finn) isn't clear, since the adventure Finn is talking about is real, but at the end he does make one up.
  • American Dad!:
    • "Office Spaceman" reveals that Francine has a hatred of left-handed people because she was originally left-handed herself as a child, but a nun she was raised by was convinced that lefties were evil and disciplined her into using her right. At the end of the episode when Steve and Hayley get her to accept the fact she's left-handed, she tries to get used to being a lefty again and handles tasks like you would expect a right-handed person doing tasks with their left for the first time would do, from writing on the shopping list illegibly to slitting Steve's throat with a butter knife (he got better).
    • "The Wrestler" has Stan obsessed with his wrestling record from high school, with a room in his house devoted to the trophies, and Francine is sick of hearing about his wrestling career and touring his museum. Odd, then, that none of the previous 126 episodes had mentioned any of this. Lampshaded by Steve commenting that he's lived in the house all his life and has never seen the wrestling museum before.
    • "Pulling Double Booty" suddenly reveals that Hayley has severe anger issues when being dumped (by "severe", we mean "rampaging death machine"), even though she was dumped by an illegal immigrant in "American Dream Factory" and harmed nobody (though she did immediately call the FBI to capture and deport him, though it was a far more controlled tantrum she soon regretted), and yet the episode implies she's been The Berserker since she was a child.
    • "Lost in Space" displays Jeff as incredibly neglectful toward Hayley in their relationship. Even considering that the compilation was rigged to leave out all the good times they shared, it's hard to buy that an Extreme Doormat like Jeff would ever look like the bad guy at all given Hayley's more consistently callous portrayal (Stan mentions in the aforementioned "Pulling Double Booty" that she dumped Jeff at least once a week before they got married).
    • A combination of this trope and Forgot About His Powers is one of the main contributors to Stan's Badass Decay as well as his status as a Designated Villain. Many episodes will have Stan develop a completely new never before seen flaw that is usually completely contradictory to his previous skillset.
    • The plot of the episode "Finger Lenting Good" pretty much revolves around this trope, where the family vows to rid their bad habits during Lent or else Bullock will cut off the finger of the person who cracks first. The bad habits in question — Stan's constant shouting in anger, Francine's smoking habit, Steve's excessive crying, Hayley's junk food addiction and Jeff's constant hugging — only show up in this episode and never reappear.note 
    • Similarly, "Dr. Klaustus" focuses on the Smiths secretly disrespecting each other in ways that have never come up before: Stan has eaten out after work to avoid Francine’s apparently horrendous cooking for a decade (despite regularly eating her meals in other episodes), Francine steals $50 from Stan's wallet for drugs every week, Hayley plays Ultimate Frisbee without Jeff because he plays it poorly (never mind that she's never shown any interest in the game before now), Jeff cannot get aroused with Hayley unless he thinks of Francine, and Steve has Greg and Terry pose as his parents in front of his girlfriend because he's ashamed of Stan and Francine. All of them are also presented as being pathologically incapable of listening to anything Klaus says unless they're not looking directly at the talking fish; Klaus is a Butt-Monkey, but they aren't usually THIS callous toward him.
  • In one episode of Chip 'n Dale: Rescue Rangers, Dale has the same reaction to chocolate that Monty usually has to cheese. It never really comes up before or after that mission.
    • Another episode has Chip and Dale suddenly obsessed with tricking each other (followed up by shouting "Got you last, got you best!") when otherwise the only thing they really compete over is Gadget's affections.
  • A few episodes of Arthur involve this.
    • One that sticks out is "Arthur Weighs In", where Arthur has an obesity/weight management problem when he had shown few to no signs of this in prior episodes (one would expect it to be Big Eater Buster Baxter to have this problem, and Arthur looks no bigger than usual either).
    • Arthur also suddenly becomes a bully out of nowhere when he continually teases Sue Ellen about her funny-looking sweater in "So Funny I Forgot To Laugh", it makes it seem like Arthur, one of the least likely characters to become a bully and who was often teased by his classmates in prior episodes, was just made a bully for the sake of having An Aesop about bullying. Flagrant is an apt description.
    • Yet another episode, "Buster Gets Real" involves Buster giving up Bionic Bunny in favor of a reality show about employees at a supermarket because it's more true to life. This happens for no other reason than for Arthur to learn that you can still be friends with someone with different interests than you. It's especially ridiculous given that the character involved is the one whose most defining trait is his obsession with fantastical stuff, so the idea of Buster rejecting something on the grounds of it being unrealistic is just absurd. To top it all off, Buster's like for said reality show is never brought up again, and he is seen still enjoying Bionic Bunny in later episodes.
    • "Speak Up, Francine" is driven by the fact that Francine has severe Stage Fright, even though by that point in the show's run she had long been established to have no issues with being up on stage performing in front of or speaking to a bunch of people (and having done so a few times completely by herself).
  • Camp Lazlo:
    • The episode "Campers All Pull Pants" involves Edward pulling down the pants of every camper in Camp Kidney, with the intention of pantsing Lazlo. In most episodes of the series, most of the campers don't wear pants, or underwear, for that matter. In fact, Edward himself doesn't wear pants and underwear until the episode's climax.
    • "Squirrel Scout Slinkman" has Slinkman suddenly display misogynistic traits out of nowhere (believing that the Squirrel Scouts are unsuited to physical activity because they're girls, a very strange thing for him to suddenly believe especially since the Squirrel Scouts usually manage to one-up the much wimpier Bean Scouts in everything), serving as a justification as to why the Squirrel Scouts decide to torment him in that episode.
  • Clifford the Big Red Dog: In “Jane and the Beanstalk”, Clifford is randomly both a bit of a crybaby and rather slow about things, as seen when Emily and the others are rehearsing a play, he won’t stop crying during a sad scene, apparently thinking it’s real.
  • Daft Planet: For one episode, with no reason given, Hudson develops intense germophobia, apparently so he can learn the lesson "being too obsessed with cleanliness isn't healthy".
  • Danny Phantom: Tucker had one of these in "Doctor's Disorders". He had a horrible fear of hospitals that we'd never seen or heard of until he had to wear a paper bag over his head just to walk past the nurse's office.
  • The episode "Ill" of Daria involves Daria spontaneously developing rashes related to her crush on Trent. The doctors involved never find a reason for it, and it never comes up again. It never came up before, for that matter, despite Daria's circumstances not changing.
  • Rufus of The Dreamstone spent the majority of the series as an almost sickly sweet Hero Antagonist, however on the rare occasion one of the heroes was required to say or do the wrong thing (usually to get the Dreamstone stolen) and get handed An Aesop, he would usually take the role. Amberley would sometimes join in on this as well, despite usually being his cautious opposite.
  • In one episode of Ed, Edd n Eddy, Kevin was shown to have a fear of needles. This was never hinted at before, nor was it brought up ever again.
  • One episode of The Fairly OddParents! revealed that Trixie Tang was actually a tomboy who liked "boy things" but is embarrassed to show that side of her to any of her friends in the popular crowd. Like a lot of things in this show brought up in just one episode, it was never mentioned again, disappointing fans.
  • Family Guy:
    • “Brian’s Got a Brand New Bag” has Brian fall in love with a 50-year-old woman named Rita, and move out of the Griffins’ house after they keep mocking her age. For the rest of the episode, Rita suddenly starts displaying memory lapses, frailty, and outdated speech patterns that never came up before, leading to Brian having an affair with a much younger woman and ruining their relationship.
    • “Jerome is the New Black” is well-known for Quagmire’s "The Reason You Suck" Speech toward Brian, and Quagmire’s raging hatred of the dog would become one of his defining traits, yet there was absolutely no sign of this animosity in previous episodes, with Quagmire being perfectly fine having Brian live with him in “The Tale of Two Brians” one season ago.
    • Speaking of Jerome, “Baby Got Black” portrays him as incredibly hateful toward white people to the point of opposing his daughter’s relationship with Chris purely because of his skin color. He fortunately learns his lesson by the end, but it’s still jarring when his aforementioned debut had portrayed him a cool, easygoing guy while Peter was the one who needed to get over his irrational hatred (over Jerome previously dating Lois rather than his race).
  • Futurama:
    • In one episode, Bender reveals that he cannot get up if he is knocked onto his back. By the end of the episode, he learns how to overcome this. Lampshaded by Fry pointing out that Bender has never once had this problem before, to which Bender responds that every other time he was always lying slightly on his side.
    • One episode gave Bender an obsession with being remembered — something he'd never even hinted about caring about before. It does manage to become a bit of a recurring character trait tied to his ego and budding megalomania.
    • Another episode parodies this. Four of Bender's ten most frequently used words were words he only used in that episode. This came with the bonus that some of said words were added into his regular slew of catchphrases ("Hot diggity daffodil!").
    • Bender's irrational hatred of Nibbler lasts exactly one episode.
    • At the beginning of "Neutopia", every male Planet Express employee is suddenly misogynist, and all the female employees suddenly act like stereotypical women. It probably was just to get the plot going, but still.
      • There's also the earlier episode of Amazon Women in the Mood, where Fry becomes as chauvinistic as Zapp Brannigan, despite usually being a well-meaning idiot. The two episodes are far apart enough to be a case of this trope.
    • In "Benderama", Bender is psychotically lazy, to the point that it's his only defining trait in that episode.
    • The human crew's sudden (and inconsistent) robot racism in "Fear of a Bot Planet" is flagrant.
      Fry: So let me get this straight. This planet is completely uninhabited?
      Bender: No, it's inhabited by robots.
      Fry: Oh, kinda like how a warehouse is inhabited by boxes.
    • Leela and Amy are suddenly extremely vitriolic and competitive towards one another in "The Butterjunk Effect", when they've gotten along fine in every other episode. Made even weirder by the fact that Fry states that they've always been this way. While Amy and Leela did have a somewhat vitriolic relationship before, it seemed to be mostly Amy having No Social Skills instead of her intentionally trying to piss Leela off, and Leela would normally respond with an annoyed expression. In this episode, her jabs are entirely intentional and Leela's responses are a lot more direct.
    • In "The Prisoner of Benda", Amy is suddenly an extreme glutton. However, her childhood obesity was a Running Gag prior to that episode, so it's more a sudden decision to fall Off the Wagon.
    • In the first "Anthology of Interest", Leela is suddenly very inhibited and unimpulsive. While the Straight Man of the group, she definitely had moments of impulsiveness (such as ejecting a delivery mid-flight just so she could rush to do something else) and said episode stood out as even weirder as later episodes would make her overly impulsive.
    • Bender's Big Score plays this for a gag, when, after drinking a six-pack of cheap beer, Bender (who is a robot) declares "For the first time ever, I gotta use the bathroom."
    • In "The Sting", Leela, usually the team's voice of reason, turns out to be almost suicidally competitive, going on an unnecessary mission and putting herself and her crew in mortal danger to prove themselves superior to Farnsworth's previous crew (who died on the mission in question). This trait does recur in the episode "Möbius Dick" and the movie Bender's Game.
    • In "The Ghost in the Machines", Fry is suddenly scared of just about everything, from parade balloons to bars of soap. This makes Bender's goal of literally scaring him to death almost too easy.
    • Parodied in the first few minutes of "Free Will Hunting", in which Bender fully cycles through several of these in under 24 hours in a way that would be unbelievable coming from anyone but Bender.
      Bender: It's been quite a journey. I dropped out of school, joined a gang, took money from a loan shark, and fell into a spiral of despair, addiction, and discount prostitution.
      Hermes: Mon, you had one hell of a day!
    • In "Proposition Infinity", Amy gets a sudden desire for bad boys, which leads her to dumping Kif and hooking up with Bender for the rest of the episode. After Bender dumps her for wanting to stay monogamous, Kif wins her back at the end by adopting some bad boy traits himself, which, along with Amy's bad-boy preferences, are never seen again.
  • The Garfield and Friends episode "Sales Resistance" revolves around Garfield's obsession with buying useless stuff off the Shopping Channel — an obsession which he has only in this episode.
  • Goofy is randomly a Big Eater in the Goof Troop episode "The Incredible Bulk." Despite this being a large part of the plot of this episode, it is never brought up before the episode or again and other episodes portray Goofy more logically as a light eater. The other characters who are more consistently played as Big Eaters (Pete and PJ to a lesser extent) are shown to be astonished by his appetite in this episode too.
  • Jackie Chan Adventures episode "Relics of Demon Past" has Jade develop a burping habit. While not completely out-of-character for her, it's only there because Jade ends up possessed by the chi of the Wind Demon and her loud, long belches could be weaponized. The burping never showed up before or after this episode.
  • In the Jimmy Two-Shoes episode "Cellphone-itis", Beezy had a severe cell phone addiction, which is never mentioned in any other episode. Jimmy did try to help him cure it, but Beezy never even gets over his cellphone dependency; in fact, his addiction ends up saving his dad!
  • Unfortunately, most of Kim Possible's Character Development is about getting a character flaw of the week that must be conquered by the end of the episode. This includes her being extremely competitive in one episode (never mentioned again) and telling white lies constantly (brought up but then presumably ignored, because it was never brought up again and she continued to do it).
  • King of the Hill:
    • One episode revolves around Hank's obsession with his guitar. Peggy claims that he pays more attention to the guitar than to her despite the fact that it's the only episode in which the guitar appears. It was eventually replaced with a similar vice: him treating the family dog Ladybird extremely well, sometimes better than he treats Bobby or Peggy. This one, however, stayed through the entire series.
    • Peggy again claims that Hank was ignoring her and was spending more time with Bobby who was doing well in Home Ec., though this was more from the longer-running character flaw of Peggy that she has to be the center of attention and acknowledged as the best at everything, even when it's incredibly clear that she's not. Bobby taking up cooking was something she supported at first until it became clear he was better at it than her and getting more attention from Hank as a result.
    • They also had an episode (Keeping Up With Our Joneses) in which the whole family took up smoking, and was over it by the end credits. It does at least go to the trouble of explaining that both Hank and Peggy were apparently smokers at some point in the past, but quit after Bobby was conceived. Hank is also seen smoking once, in a later episode (Hanky Panky) during a severely stressful situation.
    • The episode "The Honeymooners" suddenly depicts Hank's mother Tilly as being selfish, wild, reckless, and out of control. She also cheats on her husband Gary whom she loved dearly, and divorces him for a man she just met. The other characters act like she's always behaved this way.
  • Kung Fu Panda: Legends of Awesomeness: This was a recurring thing in the show with Po. Different episodes will usually have Po displaying a variety of different individual vices, whether it's rudeness, laziness, disobedience, arrogance, bad table manners, or some other dirty/annoying habit that haven't been hinted at in previous episodes. And even after Po learns his moral lesson at the end of the episode, a later episode will have Po display a different vice that's never been foreshadowed before which he has to learn another lesson with. And it's one of the main reasons Po is considered an Adaptational Jerkass in LoA compared to how he is in the movies and the other animated spinoffs.
  • The Loud House:
    • In "Brawl In The Family", the sisters use "Sister Fight Protocol" every time two sisters fight, harming Lincoln and limiting his freedom (and everyone) within the home. However, the protocol was never used or mentioned in any other episodes. To make matters worse, the girls explain the Protocol to Lincoln as if it's the first time he's heard of it, and he reacts that way too. Was he adopted?
    • In "Green House", the Loud house is characterized as a polluting factory, as each sister is a destroyer of the environment. Lincoln convinces the sisters to moderate their consumption of resources, but they get annoyed when they see him play the hypocrite with them and in the end they all go back to destroying the environment. After that, they never appear again destroying resources (and the house is never portrayed as a polluting factory again).
    • In "Spell It Out", Lucy is always harmed by her siblings, having her activities interrupted or her objects destroyed by accident. However, there was never any sign before or after that that the siblings were in the habit of harming Lucy (although there are always signs that Lincoln suffered at their hand).
    • In "The Mad Scientist", Lisa is continually pestered by her siblings, interrupting her videoconference. There is also no evidence before or after that that Lisa's work is constantly interrupted by her siblings.
  • Martha Speaks:
    • "Helen's All Thumbs" has Helen Lorraine (the girl who owns Martha) taking up video games after Ronald Boxwood shows them to her and instantly becoming obsessed with them and neglecting to feed her dogs and do her homework. She eventually starts hallucinating sprites from the game. What's especially weird is that Ronald plays video games on the regular and he never seems that obsessed and Alice Boxwood (Ronald's sister) was shown the same game in the same episode and she never developed an obsession.
    • "Martha's Dirty Habit" has a main plot that is about Martha's obsessive digging. While this main plot isn't an example of the trope as she digs a lot anyway and the obsessiveness is said to be something that only happens in springtime, there's a subplot of Daniel Lorraine (Helen's dad) giving up snacking between meals and it shows that Mariella (Helen's mother) has been trying to get him to stop. Not only is there no logical reason for Daniel to stop snacking (he's not sick, doesn't have an eating disorder and is not even overweight), Mariella has never shown any disdain for his snacking before this episode.
  • Miraculous Ladybug:
    • In "Kung Food", Chloé — while not a saint to begin with — suddenly becomes openly racist, a trait that she'd never displayed before and that would never come up again. It's blatantly clear that the trait was added just to push the episode's Aesop further.
    • In the third season, there are two non-consecutive episodes in which Marinette becomes a bully... despite in every other episode of every other season being an All-Loving Hero who regularly risks her life for people she hates. The episodes aren't part of a Face–Heel Turn arc, they're just... there.
  • My Little Pony: Friendship Is Magic:
    • “The Mysterious Mare Do Well” has Rainbow Dash's ego suddenly swell up when she rescues some ponies, in spite of the fact she had saved ponies many times before and did not have that problem.
    • In "Spike At Your Service", the titular character who up until now has been depicted as a reasonably competent and reliable assistant abruptly becomes unbelievably incompetent and clumsy, oafishly stupid and unaware, and incapable of basic tasks he's been shown doing in other episodes just fine all for the sake of some jokes.
    • In "28 Pranks Later", Rainbow Dash plays various inappropriate, cruel pranks and refuses to stop when other point out that what she's doing is wrong; meanwhile, Pinkie Pie laughs at these pranks even while objecting to them. However, in the much earlier episode "Griffon the Brush Off", both were shown to have limits, with Pinkie refusing to prank Fluttershy at all because she wouldn't take it well, and Rainbow seeing Pinkie's point and agreeing not to do it.
    • In the short "Starlight the Hypnotist", Twilight Sparkle is suddenly shown to have a crippling, debilitating, and completely over-the-top fear of ladybugs that dates back to a childhood incident, in spite of her being shown having no problem whatsoever with ladybugs before and her much-beloved "Ladybugs Awake" rhyme. Fans wasted no time making fun of this.
  • The Owl House: Eda had an addiction to Hexes Hold 'Em (a card game) in the episode "Hooty's Moving Hassle". While a gambling addiction is completely in-character for Eda, it was never brought up before this episode and is never mentioned ever again (save for "Yesterday's Lie" showing that she disposed of all of her decks) and exists solely to make B-plot more prolonged.
  • The Powerpuff Girls (1998):
    • The episode "Cover Up" reveals that Buttercup psyches herself up to fight crime by privately stroking a green blanket while repeatedly muttering "I am a good fighter". She's so dedicated to this ritual that she's late to helping her sisters save the day, despite flying out with them before and after this episode, and goes hysterical when the blanket disappears. Blossom tricks her with an ordinary rag, and when Buttercup gets back the real one that Professor was actually washing the whole time, her sisters shame her out of dependence. What makes this particularly odd is that Bubbles, who regularly sleeps with a stuffed octopus and keeps a large pile of stuffed animals, is just as judgmental as Blossom.
    • An even more egregious example is shown in "Moral Decay", in which Buttercup becomes obsessed with trying to make as much money as possible by knocking out the foes' teeth and putting them under her pillow for the tooth fairy to take in exchange for the money. Buttercup has never been known for Greed, and it even gets worse when she even attack the villains unprovoked just to gain as much money as possible without a single motivation on what she even wants to do with the money. It's especially bad when you consider that Buttercup's role in this episode was so villainous she might as well be just Princess Morbucks in disguise.
  • The Producing Parker episode "The Skinny on Parker" had Parker developing anorexia and immediately getting over it after being force-fed a sandwich.
  • Rick and Morty: From the episode "Raising Gazorpazorp", Rick suddenly becomes a chauvinist for the sake of being pitted against the man-hating matriarchs of planet Gazorpazorp. Considering his general personality, this wouldn't feel out of place if it wasn't for him also using Frat Bro slang.
  • Sam Dullard in Rocket Power has two. One in the episode "The Jinx" where he causes many predicaments for everyone else due to his jinx status, something that has never been shown in episodes beforehand. The other in "Big Air" where he suffers an asthma attack despite the fact that there were never any hints showing that he had asthma in episodes before, and it is never brought up again after that episode.
    • Reggie gets one in "Reggie and a Net" where she hogs the ball during volleyball tryouts just to show her skills at the sport. The episode was to have Reggie learn a lesson in teamwork, which doesn't fit her character considering she plays street hockey with the other guys, thus already knowing how to be a team player.
  • Sabrina: The Animated Series: One episode tells us that Sabrina always jumps to conclusions — to set up the plot about assuming her grandparents are going to divorce and going to elaborate efforts to prevent it (only to reveal they were going to renew their vows). While Sabrina displays impulsive behavior throughout the series and is too quick to use magic on several occasions, this jumping to conclusions attitude only shows up in this one episode.
  • In Sabrina's Secret Life, they did it twice in the same episode: in "Witchycology", in order to give a Green Aesop, Maritza is suddenly a Granola Girl and Cassandra has no care for the environment and leaves garbage around everywhere.
  • The Simpsons has been doing this every week for the past decade. Though some have come to receive Continuity Nods every now and then.
    • Minor but still worth mentioning: Marge being obsessed with visiting Paris (and being occasionally disappointed when the show's constant use of the Vacation Episode doesn't take the family there) was a Running Gag that continued long after the family actually lived there as ex-pats for an unknown amount of time (long enough to become fed up and go back to the United States) in the episode "Bart Mangled Banner".
    • Another aversion is mentioned in the episode where Lisa begins having an eating disorder, due to suddenly getting body-image issues. Homer looks at her at the end of the episode, waiting for her to mention the moral she learned, but Lisa admits that — like many people — she is still suffering from these body-images and isn't sure how soon it might disappear, if at all. A few episodes still make references to her having these problems. Her being a vegetarian was also a character detail that never went away (by contractual obligation to Paul McCartney, even) but the show has provided a few gags that Lisa still has a love for eating meat that she has to consciously struggle against (like loving to smell the all-meat meals Homer eats).
    • One of the most flagrant examples of this in the episode "Fear of Flying", which suddenly introduced Marge's titular phobia and linked it to several incidents in her childhood despite an earlier episode ("Mr. Lisa Goes to Washington") having had the family go on a flight with no incident whatsoever.
    • The plot of the episode "Kill Gil, Vols. 1 & 2" revolves around Straw Loser Gil Gunderson becoming The Thing That Would Not Leave in the Simpson house for almost a whole year because Marge is unable to tell him "no" and takes that long to build up the rage to finally say it. Marge Simpson, who is the biggest nay-sayer and nag in the whole series to the point that multiple episodes either revolve around her negativity ruining the lives of everybody else in the cast or make mention that she has a well-known reputation as one among all of the people in Springfield. She even gets a quick flashback to her childhood for convenient Freudian Excuse.
    • A Running Gag in the form of Homer's "life-long dream" changing every time it comes up, and Marge pointing this out (what Marge states to be Homer's actual life-long dream also changes each time).
    • One episode had Bart's hellion tendencies stemming from Homer's inability to punish Bart for his bad behavior. The same Homer who routinely strangles him for misbehaving. Which was then the focus of another episode when he went to a parenting class because strangling Bart as punishment was inappropriate. So Bart is either a borderline sociopath (at least by Lisa's standards) because Homer strangles him or Homer strangling him for anything Homer perceives as a slight is the one thing in the universe that prevents him from literally taking over Springfield Stewie Griffin-style.
    • Both Homer and Marge had separate displays of homophobia, punctuated even further by both of them showing the opposite opinion in each other's bouts. In Homer's case, he not only doesn't care about other men that he's befriended (because of plot reasons) being gay but he's so dumb that he doesn't even notice said men are gay no matter how blatant they are until another member of the family (normally whoever is the one showing discomfort this time) flat-out points it out to him.
    • "Girls Just Want to Have Sums" has the extremely common, and extremely annoying, case of this trope where male characters become inexplicably misogynistic in order to justify a Straw Feminist taking over the school so they can preach a message about gender equality. While Bart and Homer have been sexist in the past, Principal Skinner, despite acknowledging in the past that Lisa is the best student in the school, makes a crack about a former student's less-than-perfect math grades being because she's a girl, setting off the events of the episode.
    • One episode has Mr. Burns being mistaken for an alien because he glows in the dark, thanks to his continuous exposure to the power plant's toxic wastes. This trait never comes up again.
    • Like every other trope under the sun, this one has been Lampshaded by the show, too. In an episode where the family goes to a horse race, Lisa worries that Marge's intense reactions to the race means she's developing a gambling addiction. The Comic Book Guy stands up in front of them, points out that Marge already has a gambling problem, and declares this the Worst Episode Ever.
    • "The Heartbroke Kid" has Bart suddenly get hooked on junk food when Springfield Elementary gets new vending machines. He becomes severely obese in just three weeks, and even has a heart attack. He kicks his new addiction as quickly as he developed it when he discovers that his parents had turned their home into a youth hostel to pay for the Fat Camp to which they had sent him.
  • In one episode of Slacker Cats Buckley becomes a gambling addict and there's no notion before that he has that sort of characteristic and it never happens again.
  • The Smurfs (1981):
    • Smurfette is known for always attracting attention of male smurfs wherever she goes, thanks to her beauty and charm. However, in "Sister Smurf" (1982), the Smurfs suddenly start ignoring her, and this irritates her, to the point where she snubs the boys and befriends a human girl.
    • Smurfette is always treated well by male smurfs. However, in "Don Smurfo" (1986), she suffers a lot at their hands, only for her to complain that none of them are on the level of her favorite fictional character.
  • In Sonic the Hedgehog (SatAM) episodes "Sonic and the Secret Scrolls" and "Warp Sonic", the team's Ditherer and Straight Man Princess Sally becomes as reckless and pompous as Sonic. Punctuated in the former by Sonic randomly taking on a more cautious persona instead.
  • South Park:
    • In South Park: Bigger, Longer & Uncut, the boys are portrayed as innocents who don't take up swearing until seeing the Terrence & Phillip movie. They cursed just as much before and after then.
    • Justified with Randy's single-episode struggle with alcoholism. He was pulled over for Drunk Driving and forced to attend AA despite not really being an alcoholic. Impressionable joiner that he is, he takes the "admitting you are helpless to help yourself" part rather too readily to heart, and descends into full-blown dependency, convinced he has a terminal illness that forces him to drink. Though it should be noted later episodes do make him quite the alcoholic but this is the only one that focuses on it to such a degree.
    • Randy again, in the episode "Holiday Special", is revealed to have been a Christopher Columbus fanboy for all of his life, and this comes to bite him back in the ass when he decides to protest Columbus Day by tearing down Columbus statues and worse. Of course, this is just another of his many quirks that were never mentioned before.
  • Spliced:
    • In "Honorary Freak", Patricia feels out of place due to being the only non-mutant on the island, something never mentioned before or after.
    • Lampshaded in "Juice", when Entrée says "But then I won't be popular, and that's all I've ever wanted since yesterday!"
    • In "Stupid Never Means Having to Say 'I'm Sorry'", Entrée refuses to ever apologize for anything, despite having done so in multiple other episodes.
    • In "Pork Chop", Entrée is suddenly obsessed with getting respect.
    • In "Of Masters and Minions", Mr. Smarty Smarts blames Octocat for everything that goes wrong in his life, something he had never done in any prior episode.
    • Patricia gets another in "Living Hellp" in the form of spending all her time helping the other mutants.
    • Peri is usually a Nice Guy who causes trouble accidentally but in "Sgt. Snuggums" he is extremely cruel to Fuzzy.
  • SpongeBob SquarePants:
    • SpongeBob and Sandy were shown practicing karate in previous episodes and keep up the habit in later ones, but "Karate Choppers" is the first and only time that it becomes so bad that they literally can't function without doing it.
    • The episode "Procrastination" has a point where SpongeBob becomes a Ridiculous Procrastinator while trying to work on an essay from boating school. Considering SpongeBob himself is often portrayed as a Workaholic, this somewhat came out of nowhere.
    • The plot of "SpongeBob's Place" is driven by Mr. Krabs' jealousy of SpongeBob's popularity and cooking skills, but he hasn't shown any signs of it in other episodes.
    • "The Hankering" suddenly reveals that Mr. Krabs' has an irrepressible hankering for chum. This one explains it by saying that Mr. Krabs regularly go to a chum cook in secret the whole time, which still somewhat came out of nowhere.
  • In the Star vs. the Forces of Evil episode "Britney's Party", Star and Marco go to a party that takes place on a party bus, and it turns out that Marco is incredibly susceptible to motion sickness. It's so bad that even when the bus is stopped in traffic he gets ill. This has never been mentioned before or since, not even the times where he rode with his family in their car up to a campsite in "The Other Exchange Student" or in the Season 2 episode "Friend-enemies" where he partied in a bus, sang karaoke, and even rode around on a white tiger (sort of) with absolutely no problems whatsoever.
  • In the Static Shock episode "Where the Rubber Meets the Road", Adam Evans, aka Rubber-Band Man, suddenly has such extreme dyslexia that he's nearly unable to read (having to use special techniques in order to do so), and has allegedly had it since he was a child. The episode ends with Static and Adam giving a brief speech about dyslexia and the issue is never brought up again. This is particularly egregious since Adam was previously shown reading normally. One previous episode even had him state "I still have all this fan mail to read" as he picks up, opens, and begins to read said mail — and when he's retconned into being dyslexic, the fact that none of his fan mail has been opened is the first clue that he has difficulty reading.
  • Brenda's slovenliness was revealed in the same episode of Teamo Supremo as it was cured. (At least her desire to be a famous pop singer cropped up in more than one episode.)
  • The Teenage Mutant Ninja Turtles (1987) episode “Leonardo vs. Tempestra” has Leonardo, normally the most straight-laced, level-headed turtle, develop an addiction to the titular character’s video game, so much so that he obsesses over the game to the detriment of his ninja practice, and sneaks out of the lair at night to play it more. He’s never shown an obsession like this before, and hasn’t since.
  • Teen Titans Go!
    • In an episode parodying Scooby-Doo Raven plays the role of Velma. When questioned why she is suddenly wearing glasses, Raven mentions she lost her contacts. The fact that Raven is near-sighted has never been alluded to in any other media, or, flagrantly, even in any other episode of Go.
    • "Coconut Cream Pie", which very similarly spoofs Gilligan's Island, has Raven playing the role of Mary Ann, giving her a strange obsession with baking coconut cream pies and trying to make people eat them.
  • In the Theodore Tugboat epsiode, "Emily and the Tug-of-War", George suddenly becomes sexist towards Emily. George and Emily have clashed before, but it was never over each other's gender differences.
  • In Thomas & Friends, the usually kindly and well behaved Edward started to fall victim to these in order to fit into the show's increasing Aesop structure. Most evident in "Edward Strikes Out", where he suddenly develops a rather callous case of Fantastic Racism towards Rocky. Later episodes seem to settle for making him rather self-conscious, which was at least vaguely referred to in the original episodes (if not nearly to the same extent).
  • Tiny Toon Adventures:
    • In "Buster and Babs Go Hawaiian", Buster is shown to dislike riding on airplanes, even going as far as to convince the episode's writers (three then-eighth-grade girls) for a rewrite regarding the plane scene. He wasn't shown to dislike riding on airplanes when he and Babs flew back to ACME Acres from Paris, France in a previous episode, "Who Bopped Bugs Bunny?".
    • In "Thirteensomething", Babs disguises herself as a human to audition for the titular Show Within a Show. In her "Babs Bunawalskioversmith" disguise, she asks the audience how humans can stand walking in high heels, suggesting she can barely walk in them. However, in a previous short, "The Amazing Three" (part of "Love Disconnection"), she has no problem walking in high heels.
  • In an episode of Total Drama Action, Trent demonstrates an unhealthy obsession with the number 9, which he claims he's had since childhood even though he never showed any signs of it in the previous season. Harold adds that he noticed the compulsion in Trent around the time Trent first noticed Gwen liked him, which was in the previous season, but there's zero evidence of that.
  • Transformers: Prime: For the sake of Hypocritical Humor at the end of "Scraphead" episode, Miko gains a fear of spiders. While this phobia is not unusual for humans and even can be considered the stereotype girl fear, it appeared only at the end of this episode and never brought up again. And later Miko doesn't have practically any reaction (let alone fear) to Airachnid, a sadictic spider-Decepticon, so that fear was created for an one-time gag.
  • An episode of The New Woody Woodpecker Show, "Automatic Woody", has Woody dreaming about eating "Butterscotch Finger Pies", and then waking up and finding tons of empty wrappers in the various places he's stashed some for midnight snacking, and then going through lots of trouble to buy some more.
  • X-Men: Evolution:
    • In "Walk on the Wild Side", after Scott makes an uncharacteristic joke about Damsels in Distress, Jean becomes a staunch Straw Feminist who's 'sick of always being treated like the weaker sex', even though she's never been treated with anything but respect and admiration in the past - and in fact, she's usually the first of the students to get a chance at teaching the next generation. It comes out of nowhere to justify a 'women are strong' Aesop that seemed to just be an excuse to put tight leather outfits on underage girls.
    • "Target X" has a downplayed example. The episode's B-plot has Scott and Jean struggling to teach the younger X-kids, as all of them act disrespectfully. This wouldn't be out of character for some, but Amara/Magma is included in those misbehaving. Literally every other episode portrayed her as a Shrinking Violet who also respects Jean as an older sister figure.