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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.
-->-- '''WesternAnimation/{{Futurama}}'''

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 [[VerySpecialEpisode One Shot]] gag or AnAesop. (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 CharacterDevelopment, but due to the entire process being constrained to that one single episode, it's not very convincing. If the creators are more consistent about the issue, it becomes a largely InformedFlaw which drives several distinct episodes, but still is never observed in a character outside them. Shows up frequently in VerySpecialEpisode, although rarely in the TooSmartForStrangers variant for [[{{Squick}} obvious]] [[GoodFlawsBadFlaws reasons...]]

This is distinct from writers adding enduring flaws to a FlatCharacter, or hypocrisy no one notices with MoralDissonance. If the character has to try to ''lose'' the vice in the same episode, they'll find ColdTurkeysAreEverywhere (but will usually not get FlowersForAlgernonSyndrome afterwards).

Compare CompressedAbstinence, LongLostUncleAesop, CantGetAwayWithNuthin, CharacterizationMarchesOn, JerkassBall.

This trope is a sub-trope of BackstoryOfTheDay.


[[folder:Anime and Manga]]
* ''Manga/XxxHolic'' 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 {{Aesop}} is learned, all is sunshine again.
* ''Manga/HimitsuNoAkkoChan'', the original 1969 series, manages to [[BeCarefulWhatYouWishFor 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 [[LongLostUncleAesop (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 ''{{Anime/Pokemon}}'' anime, Ash has gotten so full of himself ''specifically'' to get a BreakTheHaughty 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 ''Anime/{{Digimon Adventure 02}}'' gave [[TheHeart Hikari]] a crippling reliance on her brother in the infamous [[BizarroEpisode Dark Ocean]] episode. It may have been an attempt to [[PuritySue 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.
* Louise in ''LightNovel/TheFamiliarOfZero'' went through a rapid [[TheGamblingAddict 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 ArcVillain in [[Manga/JoJosBizarreAdventureDiamondIsUnbreakable Part 4]] of ''Franchise/JojosBizarreAdventure'' 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.

[[folder:Comic Books]]
* In ''Comicbook/{{Blackhawk}}'' #240 (which is towards the end of the [[DorkAge New Blackhawk Era]]), [[EveryoneLooksSexierIfFrench André Blanc-Dumont]] has been given a crippling fear of beautiful women. He declares himself cured after punching out [[spoiler:a man disguised as a woman]]. Click [[http://www.comictreadmill.com/CTMBlogarchives/2005/2005_Individual/2005_01/000675.php here]] for an in-depth recap.
* Many authors who worked on ''ComicBook/IronMan'' 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 [[VerySpecialEpisode specific plotlines]]. Outside these plots, he may be seen drinking but is never shown having this habit as a problem. Nevertheless, he is [[NeverLiveItDown 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 90's the ''ComicBook/SpiderMan'' 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.

[[folder:Comic Strip]]
* In ''ComicStrip/BloomCounty'', Opus briefly takes up smoking because [[SmokingIsCool cigarette ads make it look cool]].

[[folder:Film - Animation]]
* In ''WesternAnimation/MadagascarEscape2Africa'', 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 realtors in ''Disney/ThePrincessAndTheFrog'' are portrayed as perfectly nice gentlemen until they reveal to Tiana that she's been outbid for her planned restaurant, where one of them notes that, "given [her] background, [[PoliticallyIncorrectVillain you're probably better off where you're at]]." The implied racism comes out of nowhere and is never brought up as a theme in the film again, and seems to be just thrown in to make the audience further sympathize with Tiana after she was genuinely outbid.

[[folder:Film - Live Action]]
* In ''Film/BackToTheFuturePartII'', 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 [[Film/BackToTheFuture 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 could also be seen as character development, however. After all, the first film had a pivotal plot point where Marty [[spoiler:successfully gets his father to stand up to a bully, and both their lives improve greatly as a result. In fact, his dad's cowardice would have doomed Marty to non-existence.]] Perhaps Marty either took that lesson to heart for himself as well, or maybe his views on cowardice are different afterwards because he is now from a timeline where his dad has been regaling him with that story since childhood. (Although the latter doesn't really match with how time travel works in this universe.)

* A staple of Literature/TheBerenstainBears; 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.

[[folder:Live Action TV]]
* Similar to the example from ''Series/{{Community}}'' below, an episode of ''Series/TheBigBangTheory'' had Leonard making up a lie to avoid seeing Penny sing due to her singing being HollywoodToneDeaf. However, other episodes have shown her singing "Soft Kitty" to Sheldon while sounding completely normal.
* An episode of ''Series/TheGoldenGirls'' 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 ''Series/{{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 ''Series/LizzieMcGuire'' featured her pal Miranda becoming anorexic and then getting over it within the course of a week. It also had Gordo becoming addicted to [[DoesThisRemindYouOfAnything Deeandeeaproximine]]... and then getting over it within the course of a week.
%%** Lizzie became an over-the-top Granola Girl for a few days.
* An episode of ''Series/TheFactsOfLife'' has Sue Ann getting, and recovering from, anorexia.
* D.J. became worried about her weight in an episode of ''Series/FullHouse''. 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 ''Series/DiffrentStrokes'' has Kimberly getting bulimia.
* An episode of ''Series/SpinCity'' 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.
* ''Series/NedsDeclassifiedSchoolSurvivalGuide'', "Guide to School Records"- Ned is a well-intentioned, "[[BrilliantButLazy smart but]] [[BookDumb 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. {{Flashback}}s 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 ''Series/{{Smallville}}''.
** Mimi Clark in ''Series/{{Jericho}}''.
** Marissa Taylor in the defunct Australian comedy/drama ''[[http://en.wikipedia.org/wiki/Always_greener 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 ''Series/FullHouse''
* A particularly extreme example appeared on ''Series/{{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.
* ''Series/{{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 one about Ross overpronouncing every word applies, though.
** Ridiculously played straight with Chandler's shyness and inability to even ''talk'' to attractive girls in "The One With The Cheap Wedding Dress" (where Joey and Ross try to date the same girl). In the entire series preceding that point, although he was usually unlucky in love in the long run, he'd been shown as an admirably competent pickup artist capable of striking up conversations and dispensing hilarious off-the-cuff witticisms with attractive women in almost any situation. He occasionally struck out, but he'd certainly never had a problem ''talking'' to any of them. This is particularly jarring considering "TOW Ross Can't Flirt" two seasons earlier, where Ross gets jealous at how easily he can talk to women and [[HoYay Chandler even offers to flirt with him to show how it's done]].
** 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 ColdTurkeysAreEverywhere 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...
* {{A|nAesop}}esops about snoring tend to suffer from this, as characters spontaneously develop the habit and then no reference is made to this afterwards. Examples include Joey from ''Series/{{Friends}}'' (Chandler can suddenly hear him through the wall after living with him for five years with no problem), Charles Winchester from ''Series/{{MASH}}'' (due to allergies), and Homer Simpson from ''WesternAnimation/TheSimpsons'' (he suddenly starts snoring loudly after years of sleeping with his wife).
* Done in ''Series/RedDwarf'' 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.
* ''Series/{{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.
* ''Series/StarTrekDeepSpaceNine'':
** When Odo becomes involved with the [[BiggerBad Female]] [[EvilMentor Changeling]] in "Behind the Lines" and "Favor the Bold," he becomes utterly obsessed with [[GRatedSex linking]]. Given that their linking scenes have the feel of [[DoesThisRemindYouOfAnything 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 ''Series/StarTrekVoyager'', 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.
* Happens all the time in ''Series/{{Degrassi}}'', largely as a result of ExecutiveMeddling. 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 VerySpecialEpisode 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 [[spoiler: committing suicide]], and Katie pops pain pills for several episodes before being sent to rehab).
* Vampire's strong vulnerability to werewolf blood in ''Series/BeingHumanUK'' Wasn't heard of and only revealed very offhandedly several seasons in.
* Tommy from ''Series/ThirdRockFromTheSun'' 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.
* ''Series/{{MASH}}'': the plot of episode "C*A*V*E" is based on Hawkeye's suffering from crippling claustrophobia, which had never been mentioned before and was never referred to again.
* Likewise Commander Straker in the ''Series/{{UFO}}'' episode "Sub-Smash". He develops claustrophobia on a submarine despite operating numerous times in spacecraft which should give him similar problems.
* ''Series/TheProfessionals'': 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 the ''Series/MalcolmInTheMiddle'' episode where Francis turns out to have been in AA despite never having been shown getting drunk in previous episodes. [[spoiler: The other characters find out that he had all the signs of alcoholism ''except'' for drinking.]]
* ''Series/{{Baywatch}}'' was rather terrible with this. DependingOnTheWriter, 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.
* ''Series/HowIMetYourMother''
** 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. [[JustifiedTrope 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 [[UnreliableNarrator 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.
* ''Series/SavedByTheBell'': Jessie Spano's one-episode [[http://www.youtube.com/watch?v=ljtuGoIIKGs caffeine pill addiction.]]
* Blair Warner in ''Series/TheFactsOfLife'' develops a one-show gambling addiction in a 1986 episode. At the end, she swears it off [[http://www.youtube.com/watch?v=51agQ6Ny-ps&NR=1 only for a woman behind her to hit the jackpot using the same machine]]. HilarityEnsues.
* In the Lent episode of ''Series/FatherTed'', while Ted's smoking and Jack's drinking have been previously established, Father Dougal's addiction to roller blading only exists in this episode. However, as the whole series runs on NegativeContinuity and RuleOfFunny, this scarcely seems to matter.
* An odd example from ''Series/TwentyFour'' 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 ''Series/TensouSentaiGoseiger'' 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.
* ''Series/{{Glee}}'':
** In "The Power of Madonna", the boys are suddenly shown mistreating the girls in various ways in order to setup 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.
** 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 [[VerySpecialEpisode 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, [[DependingOnTheWriter 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 populairty isn't everything

* Stumpy's gambling addiction isn't mentioned at all in season one of ''Series/{{Carnivale}}'', 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 VerySpecialEpisode of ''Series/BoyMeetsWorld'', 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 ''Series/{{Alice|1976}}'', 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 [[OutOfCharacter 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 ''Series/{{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.
* ''Series/TheMaryTylerMooreShow'' episode "Mary's Insomnia" has Mary turning to sleeping pills to get over a new-found case of insomnia, becoming dependent on them, and getting over her addiction, all within one 25-minute episode.
* [=CeCe=] Jones in one episode of ''Series/ShakeItUp'' is revealed to be [[LIsForDyslexia dyslexic]]. Although she is portrayed throughout as BookDumb, the dyslexia is never mentioned again. This is an ActorAllusion, since Bella Thorne suffers from this in RealLife.
* ''Series/{{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 ''Series/MamasFamily'', 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.
* ''Series/{{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]]How even someone as stuffy as Niles had never eaten fast food before, considering he wasn't born to wealth and privilege, is best not dwelt upon[[/note]] but they still never get mentioned again afterwards.
* A VerySpecialEpisode of ''Series/HannahMontana'' 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 ''Series/ThirtyRock'', 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 TooDumbToLive .
* ''Series/FrontierCircus'': 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 ''Series/{{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 VictimOfTheWeek had those traits.

[[folder:Video Games]]
* In Year 2 of ''VideoGame/GrimFandango'', 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 [[AddictionDisplacement an outlet for Glottis's obsession with speed]].
* ''VideoGame/MoshiMonsters'': 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.

* Inverted and possibly subverted in the webcomic ''{{Webcomic/Narbonic}}'', where Dave's chain-smoking habit is established early on and continually referenced. However, after [[spoiler: 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 ''Webcomic/{{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.

[[folder:Web Original]]
* Phelous notes this trope in his review of ''Series/MortalKombatConquest''. In an episode where Siro must overcome his pride, Phelous notes that the character has never seemed particularly proud before, has nonsensical motivations in the episode, and actually seems to become more egotistical in later episodes.


[[folder:Western Animation]]
* The ''WesternAnimation/GarfieldAndFriends'' 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.
* ''WesternAnimation/DannyPhantom'': 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.
* ''WesternAnimation/TheSimpsons'' has been doing this every week for the past decade. Though some have come to receive {{Continuity Nod}}s every now and then.
** One memorable aversion came with Marge's gambling problem, which was expected to become forgotten by the next episode like most but has been managed to be referenced countless times.
** 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.
** 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.
** A RunningGag in the form of Homer's "life-long ambition" changing every time it comes up, and Marge [[LampshadeHanging pointing this out]].
** 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.
** 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.
** ''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 StrawFeminist 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 of the most flagrant cases takes place in the later seasons of ''WesternAnimation/StaticShock''. In one of several {{Very Special Episode}}s, Adam Evans (aka Rubber-Band Man) out of nowhere suddenly has dyslexia, and from what we're told, has had it since he was a child. And not just a mild case for that matter, more like sees a stop sign written in Arabic type. The episode ends with Static and Adam giving a brief speech about dyslexia a la AndKnowingIsHalfTheBattle and Adam's reading disorder is never brought up again. This is particularly egregious, since Adam ''was previously shown reading.'' In fact, one episode had him mention aloud (with nobody around for him to be trying to lie to) "I still have all this fan-mail to read" as he picks up, opens, and ''begins to read said mail'' (even more of a retcon since when his dyslexia appears in this episode, the fact that none of his fan-mail was open becomes a clue that he could not read). This is seen as one of the weaker episodes.
* ''WesternAnimation/{{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.
** 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 catch phrases ("Hot diggity daffodil!").
** Bender's irrational hatred of Nibbler lasts exactly one episode.
** In 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 got 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 NoSocialSkills 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 RunningGag prior to that episode, so it's more a sudden decision to fall OffTheWagon.
** In the first Anthology of Interest, Leela is suddenly very inhibited and unimpulsive. While the StraightMan 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 [[{{Flanderization}} would make her]] overly'' impulsive.
* An episode of ''The New WesternAnimation/WoodyWoodpecker 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.
* Unfortunately, most of ''WesternAnimation/KimPossible'''s CharacterDevelopment 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).
* Brenda's slovenliness was revealed in the same episode of ''WesternAnimation/TeamoSupremo'' as it was cured. (At least her desire to be a famous pop singer cropped up in more than one episode.)
* The ''WesternAnimation/ProducingParker'' episode "The Skinny on Parker" had Parker developing anorexia and immediately getting over it after being force-fed a sandwich.
* Sam Dullard in ''WesternAnimation/RocketPower'' 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.
* One episode of ''WesternAnimation/TheFairlyOddParents'' revealed that [[RichBitch Trixie Tang]] was actually a {{tomboy}} who liked "boy things" but is embarassed 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.
* ''WesternAnimation/KingOfTheHill'':
** 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 [[SmallNameBigEgo 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 in which the whole family took up smoking, and was over it by the end credits. It does go to the trouble of explaining that both Hank and Peggy were apparently smokers at some point in the past, at least. Hank does smoke once, in a much later episode (''Hanky Panky'') during a severely stressful situation.
** The episode "The Honeymooners" 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 divorced him for a man she just met, the other characters act like she's always behaved this way.
* In an episode of ''[[WesternAnimation/TotalDrama 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.
* An episode of ''WesternAnimation/JimmyTwoShoes'' had Beezy have a severe cell phone addiction which is never mentioned before or after. He never gets over it, in fact his addiction saves everyone.
* In one episode of ''WesternAnimation/ChipNDaleRescueRangers'', 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 [[CockFight Gadget's affections]].
* In one episode of ''WesternAnimation/SlackerCats'' Buckley becomes [[TheGamblingAddict a gambling addict]] and there's no notion before that he has that sort of characteristic and it never happens again.
* ''WesternAnimation/AmericanDad'':
** "Office Spaceman" reveals that Francine has a hatred of left-handed people. This is because she was originally left-handed 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 [[DisproportionateRetribution immediately call the FBI to capture and deport him]]), and yet the episode implies she's been TheBerserker since she was a child.
** A combination of this trope and ForgotAboutHisPowers is a main contributor of Stanís BadassDecay as well as his status as a DesignatedVillain. Many episodes will have Stan develop a completely new never before seen flaw that is usually completely contradictory to his previous skill set.
** 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 [[ItMakesSenseInContext 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]]Francine's smoking did pop up now and again, but seldom enough to count for this trope[[/note]]
* ''WesternAnimation/SouthPark'':
** In ''WesternAnimation/SouthParkBiggerLongerAndUncut'', the boys are portrayed as [[ChildrenAreInnocent 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 Driv|er}}ing 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 was never mentioned before.
* ''WesternAnimation/AdventureTime'':
** 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 TimeSkip 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.
* Goofy is randomly a BigEater in the ''WesternAnimation/GoofTroop'' 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.
* Rufus of ''WesternAnimation/TheDreamstone'' spent the majority of the series as an almost sickly sweet HeroAntagonist, however on the rare occasion one of the heroes was required to say or do the wrong thing and get handed AnAesop, he would usually take the role. Amberley would sometimes join in on this as well.
* In ''WesternAnimation/SonicSatAM'' episodes "Sonic and the Secret Scrolls" and "Warp Sonic", the team's [[TheDitherer Ditherer]] and StraightMan Princess Sally becomes as reckless and pompous as Sonic. Punctuated in the former by Sonic randomly taking on a more cautious persona instead.
* In ''WesternAnimation/ThomasTheTankEngine'', 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 FantasticRacism towards Rocky. Later episodes seem to settle for making him rather self conscious, which was at least vaguely referred to in the original episodes ([[{{Flanderization}} if not nearly to the same extent]]).
* ''WesternAnimation/XMenEvolution'': In ''Walk on the Wild Side'', after Scott makes an uncharacteristic joke about Damsels in Distress, Jean becomes a staunch StrawFeminist 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. It comes out of nowhere to justify a 'women are strong' aesop that seemed to just be an excuse to put [[FanService tight leather outfits]] [[{{Squick}} on underage girls]].
* In ''[[WesternAnimation/SabrinaTheAnimatedSeries Sabrina's Secret Life]]'', they did it twice in the same episode: in "Witchycology", in order to give a GreenAesop, Maritza is suddenly a GranolaGirl and Cassandra has no care for the enviroment and leaves garbage around everywhere.
* A few episodes of ''WesternAnimation/{{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 BigEater Buster Baxter to have this problem, and Arthur [[HollywoodPudgy looks no bigger than usual either]]).
** Arthur also suddenly [[OutOfCharacterMoment 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 AnAesop about bullying. Flagrant is an apt description.
** Yet another episode, "Buster Gets Real" involves Buster suddenly dropping Bionic Bunny in favor of a reality show about employees at a supermarket. (Yes, [[CloudCuckooLander Buster]].) This happens for no other reason than for Arthur to learn that you can still be friends with someone with different interests than you. 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.
* ''WesternAnimation/{{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.
** {{Lampshade|Hanging}}d 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 NiceGuy who causes trouble accidentally, but in "Sgt. Snuggums" he is extremely cruel to Fuzzy.
* ''WesternAnimation/TeenTitansGo''
** In an episode parodying ''Franchise/ScoobyDoo'' 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 ''Series/GilligansIsland'', 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 ''WesternAnimation/StarVsTheForcesOfEvil'' 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 camp site in "The Other Exchange Student" or in the Season 2 episode "Friendenemies" where he partied in a bus, sang karaoke, and even rode around on a white tiger (sort of) with absolutely no problems whatsoever.
* ''WesternAnimation/MarthaSpeaks'':
** "Helen's All Thumbs" has Helen Lorraine (the girl who owns [[TalkingAnimal Martha]]) taking up video games after [[TheBully Ronald]] [[DeadpanSnarker 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 [[LovableJock Alice]] [[TheKlutz 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.
* In the ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' episode "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. Suffice to say it did ''not'' sit well with many fans and frequently pops up on "worst episodes" lists.
* ''WesternAnimation/TinyToonAdventures'':
** In "[[Recap/TinyToonAdventuresS2E8BusterAndBabsGoHawaiian 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, "[[Recap/TinyToonAdventuresS1E50WhoBoppedBugsBunny Who Bopped Bugs Bunny?]]".
** In "[[Recap/TinyToonAdventuresS3E1Thirteensomething Thirteensomething]]", Babs disguises herself as a human to audition for the titular ShowWithinAShow. 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 "[[Recap/TinyToonAdventuresS2E10LoveDisconnection Love Disconnection]]"), she has no problem walking in high heels.
* The ''WesternAnimation/CampLazlo'' 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, [[HalfDressedCartoonAnimal 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.