{{Fanon}} is an odd thing. Fans come up with it for many reasons. Because WordOfDante says so, because WordOfGod [[ShrugOfGod never said so]], because it's [[SarcasmMode the only plausible]] [[EpilepticTrees explanation of an event]] (sometimes it even is!), or just because it's fun!

One popular form of fanon, however, is that which is created simply to make {{shipping}} the {{OTP}} easier. This is the fanon referred to as The Ship's Motor. In the way that having a motor is helpful to a literal ship, this piece of fanon is helpful to a FanFic writer's ship. But it's not enough for it to be just helpful, to truly be The Ship's Motor, a piece of fanon must have no other clear purpose than to make shipping two characters more plausible. [[TropesAreNotBad That does not mean the piece of fanon has to be contrived, or even implausible]]. It can be neutral, or even plausible in {{canon}}. [[TropesAreNotGood Plausible or not]], many of these become well-regarded in the {{fandom}} because [[FanPreferredCouple so many fans ship the pairing.]]

Only tangentially related to the Youtube vidcast WebVideo/TheShipsCloset.



[[folder:Anime & Manga]]
* Some ''Manga/{{Naruto}}'' fanfics with the [[KissingCousins Neji]]×[[IncestIsRelative Hinata]] couple have the two arranged to marry in order to keep the Byakugan bloodline trait within the family, thus precluding any other ships.
* Many ''Anime/NeonGenesisEvangelion'' fanfics with the Shinji×Rei pairing will bring up various arguments and bits of fanon that make the pairing less problematic by [[IncestIsRelative reducing the degree of genetic connection]] between the two.
* ''Anime/DeathNote'': During the time period when L and Light were [[ChainedHeat handcuffed together]], it is not mentioned how they did things such as sleep, bathe etc. It's quite possible (and likely) that they were unhandcuffed and someone else kept an eye on Light- but slash fic writers have decided they ''definitely'' slept in the same bed and bathed together.

[[folder:Films -- Live-Action]]
* In ''Film/TheForceAwakens'' fandom, the idea that Rey and Finn are both sexually and romantically inexperienced due to their unusual childhood is popular among fans who ship [[OneTrueThreesome Rey×Finn×Poe]]. This allows Poe to be introduced to an established Rey×Finn relationship in the process of [[PracticeKiss "teaching" them how to kiss]] and so on. It also has some support through WordOfSaintPaul, with John Boyega (who plays Finn) stating that he believes Finn is a virgin.

* ''Literature/HarryPotter'':
** The Head Boy and Head Girl [[{{lemon}} share quarters]]. Which seems particularly odd since [[FridgeLogic the Founders use magic to keep boys from even]] ''[[FridgeLogic visiting]]'' [[FridgeLogic the girls' dormitories]], but presumably the reasoning is that anyone who earns that title probably has enough sense to avoid unfortunate mishaps. Some of the saner examples downplay the trope a bit and give them separate sleeping quarters but a shared study/living room.
** There's a million of these, really. There are also "Marriage Law fics," where the Ministry passes a law forcing purebloods and Muggle-borns to marry against their will (usually for the sake of [[HotForStudent Snape×Hermione]] or [[DracoInLeatherPants Draco]]×[[FoeYay Hermione]]). This... worked better before the last couple of books came out (not that was particularly plausible then). Another plethora of stories has Hermione wind up really being a Pureblood so that she more easily hook up with [[DracoInLeatherPants Malfoy]] or [[EnsembleDarkhorse Zabini]]. Changing a character's heritage to pair her with an unrepentant PoliticallyIncorrectVillain? UnfortunateImplications be danged!

[[folder:Live-Action TV]]
* ''Series/StarTrekTheOriginalSeries'':
** Kirk [[SlashFic can empathically sense]] when Spock is going into [[HumpOrDie Pon Farr]]. This actually crops up in one of the ''published'' TOS books, "Killing Time", which was famously recalled and edited after the publishers realized the author was a Kirk×Spock shipper.
** Also please note that Creator/GeneRoddenberry's [[WordOfGod novelisation]] of ''Film/StarTrekTheMotionPicture'' stated that it was ''Kirk's mind'' that called to Spock across the light years and ended his chances at the Kolinahr. Maybe not such a stretch after all...
** Similar to the ''Literature/HarryPotter'' example above, a significant number of [[SlashFic fics]] feature the idea that the Captain and First Officer have adjacent quarters and share a bathroom. Canonically their quarters appear to be on different decks altogether, but this piece of {{Fanon}} is so widely used (and convenient) that its use can be considered an [[AcceptableBreaksFromCanon Acceptable Break From Canon.]]
* In the ''Series/{{Firefly}}'' fandom, River/Jayne shippers often use the idea that Jayne's thoughts are "clear" or "simple" as part of the reasons River might be attracted to him.
* Kara and Lee of ''Series/{{Battlestar Galactica|2003}}'' are believed to have gone to flight academy together [[{{Jossed}} even though canon has discredited this]].
* Faith of ''Series/BuffyTheVampireSlayer'' is often portrayed in fanfic as bisexual, building on her on-screen AnythingThatMoves nature. This is, of course, useful for pairing her with Buffy, Willow, or any other female character. This attitude of making a character bisexual can also extend to Buffy herself when pairing her up with [[IfItsYouItsOkay Willow]] in earlier seasons or Faith or Tara in later seasons.
* ''Series/TheXFiles'' fans had a setup for Mulder and Scully's hotel arrangements - adjoining rooms, door in the middle connecting them -- ostensibly so they could protect each other better from one their Monsters of the Week deciding to attack.
* It became fanon for [[Series/{{Popular}} Brooke/Sam]] shippers that they had an adjoined bathroom connecting their bedrooms, even though there was no such thing.
* ''Series/ICarly'':
** [[JerkAss Sam]]×[[HollywoodNerd Freddie]] [[DoubleStandardAbuseFemaleOnMale belligerent sexual tension]] shippers use a reply that WordOfGod left on his blog as their motor, it's along the lines of "their bickering is a game, and maybe they are afraid to stop playing". The reasonable idea is that any 'game' is their inability admit they really care for each other as friends. The Sam/Freddie shippers take it as the 'game' is wilfully ignoring romantic feelings for each other because they enjoy fighting, and one-day will stop playing and [[RelationshipUpgrade get together]].
** Sam being bi is a big piece of fanon that's very useful in bringing out Carly's IfItsYouItsOkay feelings for her in the Carly/Sam fandom. The other common fanon is to make Carly and Sam both bisexual to make their mutual attraction easier or help ship Carly with Shelby Marx or Missy.
* ''Series/PowerRangersSPD'': Sky being Bridge's roommate because his hardnosed-ness means his thoughts are more ordered and less apt to bleed over and give Bridge a psychic headache. (Actually, Sky's as emotional as anyone else, if not ''more.'' He just feels the need to act like the Perfect Officer� 24-7 because he wants to follow in the foosteps of his legendary pa.)
* ''Series/{{Supernatural}}'': Despite the prevailing opinion of the fandom, Sam and Dean having amazingly [[IncorruptiblePurePureness bright]]/[[PureIsNotGood pure]] souls--despite [[FireAndBrimstoneHell everything they've been through]]--has never actually been stated in canon. Their various [[HoYay angel lovers]] will be so disappointed...

[[folder:Video Games]]
* The Portal fandom has a habit of taking bots like [=GLaDOS=] and Wheatley, and making them humanoid, either by downloading them [[BecomeARealBoy into a human body]], [[RidiculouslyHumanRobots giving them some sort of android]], or [[ArtificialHuman finding a way to mix the two]]. This is done in part to make writing their expressions easier in fanfiction, but mainly it seems to pair them with [[PlayerCharacter Chell]]. This was only reinforced after [[spoiler: Portal 2 revealed [=GLaDOS=] herself [[BrainUploading used to be human]]]]. Wheatley being the more human of the two (with less [[ElectronicSpeechImpediment mechanical feedback]] in his speech, [[BadLiar truly]] [[ArtificialStupidity incredible]] [[TheDitz fallibility]], and "facial" gestures,) expect his androids and cyborgs to appear more natural, while [=GLaDOS=]'s will have wires or damage right out in the open.

[[folder:Web Animation]]
* ''WebAnimation/{{RWBY}}'': Many fics about [[ChildhoodFriends Ren and Nora]] have them [[SleepCute platonically]] sleeping together. This helps to ramp up sexual tension if the fic is romantic, but it's also an extrapolation of the very close partnership they have in canon.

[[folder:Western Animation]]
* Like the ''Buffy'' example above, Cody on ''WesternAnimation/TotalDrama'' is often made bisexual, because while it's ''very'' clear that [[CasanovaWannabe Cody likes girls]], most fans prefer a bit of HoYay between him and [[AmbiguouslyGay Noah]].
* ''WesternAnimation/InvaderZim'':
** The fandom will often justify sex with Irkens by claiming that Irkens have sex ''at all.'' Canon seems to imply that they're all grown in a big factory, and naked Irkens have no apparent genitals. It's particularly common to assume that they lay eggs.
** Also, [[IdiosyncraticShipNaming ZATR]] fans often portray Zim and Tak having known each other prior to the events on Devastis, even to the point of having been best friends since they were smeets. From the way Zim acts when Tak reveals herself on Earth it seems they never met before.
** Though [[BrotherSisterIncest Dib/Gaz]] isn't very popular, those who ''do'' ship it sometimes use a WordOfGod statement about Dib being an experiment created by Membrane to suggest that he and Gaz [[NotBloodSiblings aren't really related]]. The creator notably never mentioned ''how'' Gaz fits into that scenario; since {{Fanon}} often makes Dib [[TrulySingleParent Membrane's clone]], some extend this theory to make Gaz a clone of Membrane's dead wife in a weirdly literal case of GenerationXerox.