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ObviousCrossoverMethod: Under Administrivia/TropesNeedingTRS due to seeing like it should be YMMV when it currently is not.
Per [[https://tvtropes.org/pmwiki/query.php?parent_id=131536&type=att ATT]], all wick (barring sandbox duplicates) have been counted (54/54).
[[folder:Non-YMMV in source material (5/54)]]
# Franchise.FateSeries: The entire concept of Servants means that it's easy to summon a crossover character as a Servant. There are even canonical examples of fictional characters being summoned, so they don't even need to be established as previously existing in the same universe. Likewise, characters from other settings starting their own Grail Wars.
# Manga.MazingerZVersusTransformers: While the Space Bridge is generally a stable method of travel in ''WesternAnimation/TheTransformers'', in the episode "Child's Play" a malfunction sent a group of Transformers to a completely different planet. For this crossover, the lead observer takes advantage of the Space Bridge's explosion to deliberately send the Transformers to Mazinger Z's world.
# MediaNotes.JennyEverywhere: Since Jenny is defined by the gimmick that there is a version of her in ''every'' reality, it is part of the premise itself that she supposedly ''already'' exists in whatever fictional universe you want to write about — ''just'' off-screen… And that's before you go into the fact that most versions of Jenny are [[DimensionalTraveler Dimensional Travelers]] who can leave their home reality at will to explore.
# TabletopGame.InfiniteWorlds: As mentioned under the Canon Welding entry, the setting itself was basically built to allow crossovers to happen by way of interdimensional travel.
# VideoGame.MortalKombat11: Kronika's Hourglass, which can bring in characters from other timelines, and is implied to be the explanation for the guest characters' appearances.
[[/folder]]
[[folder:Non-YMMV in fan material (12/54)]]
# FusionFic: ''Fanfic/{{Paradoxus}}'': The Setting Merge flavor, to be specific. [[VideoGame/WorldOfWarcraft Azeroth]] and [[WesternAnimation/WinxClub Magix]] now happen to exist in the same multi-dimensional universe. It's just they are too far apart that, ''normally'', they would've never interacted at all. Here we have Galadwen and Eudora's constant interdimensional traveling and meddling ''and'' [[spoiler: Daphne]]'s time travel shenanigans, so things are definitely not normal (more like deranged). Now, there are already some canon points that keep this idea within the realm of possibility: there are elves in both franchises, [[ObviousCrossoverMethod interdimensional traveling is confirmed and used]] in both of them, and both of them have entities capable of creating entire dimensions (the First Ones for ''World of Warcraft'' and the Great Dragon for ''Winx Club''). Though it's worth noting the Great Dragon is not equal to the First Ones, but to the Titans (like Sargeras), which helps to even out the power scales and avoid a PowerCreepPowerSeep scenario and allows for the [[TeamUpSeries teaming-up plot]] this crossover roots from.
# TropesInAggregate: ObviousCrossoverMethod '''Notes it's only a trope as a trend in works.'''
# Fanfic.ARedRoseInTheBlueWind: The story intersects the paths of both the ''Sonic'' and ''RWBY'' worlds through the Chaos Emeralds, only this time they work as intended, as opposed to the more common accident plot.
# Fanfic.CodePrime: In lieu with some traditional ''Transformers'' crossover plots, the worlds intersect through a crashed ''Ark'' and ''Nemesis''.
# Fanfic.IWannaBeTheTroll: While trying to figure out what the trollfic will be about, the AuthorAvatar decides that, since canon IWBTG is already a MassivelyMultiplayerCrossover, she can use the setting as a vehicle to send The Girl around various canons for funsies. '''An in-universe/meta example.'''
# Fanfic.MassFoundations: TeleportationMisfire: What kicked off the plot of the fic, adopting a pretty common ObviousCrossoverMethod, thus making Ethan's motivation to find a way back home, though it was a self-imposed error in improving the Transportalponder and Big Mountain being Big Mountain.
# Fanfic.{{Paradoxus}}: FusionFic: The Setting Merge flavor, to be specific. Azeroth and Magix now just happen to exist in the same multi-dimensional universe, it's just they are too far apart that, ''normally'', they would've never interacted at all. Normally. Here we have Galadwen and Eudora's constant interdimensional traveling and meddling ''and'' [[spoiler: Daphne's time travel shenanigans]], so things are definitely not normal (more like deranged). Now, there are already some canon points that keep this idea within the realm of possibility: there are elves in both franchises, [[ObviousCrossoverMethod interdimensional traveling is confirmed and used]] in both of them, and both of them have entities capable of creating entire dimensions (the First Ones for ''World of Warcraft'' and the Great Dragon for ''Winx Club''). Though it's worth noting the Great Dragon is not equal to the First Ones, but to the Titans (like Sargeras), which helps to even out the power scales and avoid a PowerCreepPowerSeep scenario and allows for the [[TeamUpSeries teaming-up plot]] this crossover roots from.
# Fanfic.PonyvilleGoesToTheDragons: Like most [=FiM=] cross-over fics, this one starts with Twilight screwing up a spell and teleporting the cross-over characters to her world. In a twist though, the spell ''was'' being performed correctly, but what happened was that Applejack ended up startling Twilight just as she was in the middle of casting the spell, causing her to jump and smudge one of the runes used in the spell. (A fact that AJ feels really guilty about.)
# Fanfic.{{Xendra}}: By using the fact characters could choose different outfits for [[Recap/BuffyTheVampireSlayerS2E6Halloween the fateful Halloween]] when Ethan Rayne [[BecomingTheCostume turned everyone into their costumes]].
# Pantheon.GamingGenresNToZ: A plethora of people Sora met across his travels are in the Pantheon, including most if not all of the Princesses of Heart he came across in his adventures. [[AllLovingHero Sora has been renown for his upbeat personality that grants him many friends across many different worlds]]. As long as you do not mess with him or are doing anything evil in front of him, Sora will extend his hand. His ability to make friends is what may be Sora's greatest asset, as he can connect with people's hearts and draws his power from those connections. That applies to people Sora may have never even met as seen with how his heart repairs a broken Ventus. [[ObviousCrossoverMethod The Pantheon opens Sora to a plethora of new worlds to explore and gain more connections]]. Sometimes, this results in Sora landing on their while a conflict he has no context for occurs. People like to point out as the Keybearer, [[AlienNonInterferenceClause Sora should not meddle in the affairs of other worlds as much as he does but Sora would like to say that it is not his fault he ends up where he goes]].
# Roleplay.CirqueMystique: The Multiverse and MutualMasquerade.
# WebAnimation.TurnaboutStorm: Naturally, Twilight messing up a spell causes Phoenix getting pulled to Equestria. [[spoiler:The twist is that the "messing up" part is a complete lie. Not only that, but TheStinger in ''Part 5'' implies that Celestia herself was the one who actually messed up the spell, getting the late Mia Fey, who later suggested Phoenix instead.]]
[[/folder]]
[[folder:YMMV (26/54)]]
# CommonCrossover: Some fandoms [[ObviousCrossoverMethod are so accessible]] that they're crossed with just about everything else. '''CommonCrossover has the same issue of if it should be YMMV, putting here as examples isn't about creator intent.'''
# FanficTropes: ObviousCrossoverMethod: A story has an obvious method through which crossovers can occur.
# FandomSpecificPlot.AnimatedFilms: "Casita creates a door/doors to elsewhere" is proving to be an ObviousCrossoverMethod.
# FandomSpecificPlot.AnimeAndManga: The show's basic premise, where Louise inadvertently summons a person from another universe during her school's Springtime Summoning Ritual, functions as an ObviousCrossoverMethod allowing her to summon anyone or anything to replace Saito. Or, alternatively, somehow mess up and send herself to the other universe: be it directly stranding herself in the new setting or being kidnapped/escorted by a resident deity or otherwise powerful entity from that world (usually as retribution for her previous attempts nearly taking someone from their world). In fact, this plot is so common that crossover fics using this framework form the majority of fanfic you'll find for the series in both its Western and Japanese fandoms.
# FandomSpecificPlot.HarryPotter: "The Late To Hogwarts Fic," in which a young wizard or witch doesn't get their invitation to Hogwarts at age 11, or is unable to go, until later age (usually when romantic plots would be more okay, so from fourth year up) — the other way is to introduce a transfer student ([[SelfInsertFic who's usually from the same country/general area and of the same background as the author]], [[WishFulfillment and is very similar to them in all aspects, only better]]). The latter type has the added benefit of 1) making up a new, totally awesome wizarding school 2) enabling the character to have a unique, totally cool wand 3) creating an explanation for [[WrongContextMagic unseen-in-Britain]], [[{{Chuunibyou}} totally super magic]] 4) allowing the character to have an inherited {{katana|sAreJustBetter}} 5) being an ObviousCrossoverMethod. Details not tying into the character's origins and entrance into Hogwarts usually follow the normal self-insert/wish-fulfillment procedure. This plot was later worked into the video game ''VideoGame/HogwartsLegacy'', which is only sorta AscendedFanon since the game itself is considered non-canon.
# FandomSpecificPlot.{{Literature}}: Many fanfics give the main character a different set of powers. This is often used as an ObviousCrossoverMethod.
# FandomSpecificPlot.{{Supernatural}}: Crossovers with ''Series/DarkAngel'' where Creator/JensenAckles's characters Ben and Alec were cloned from Dean; an ObviousCrossoverMethod, since Ben and Alec are already genetically engineered twin clones. Frequently with Dean and Sam discovering the twins as children and adopting them, thus fixing [[TykeBomb the abusive childhoods]] the twins endured in canon.
# FandomSpecificPlot.TheOwlHouse: Crossovers with ''Franchise/LittleWitchAcademia'' are common, due to both shows having a very similar premise (a {{Muggle}} with brown hair attends a school for witches and has endless romantic subtext with a green-haired witch prodigy). These stories often has [[ObviousCrossoverMethod Luna Nova be another school on the Boiling Isles]], and Luz and Akko bond over their similar struggles with magic. Wether Akko is a witch or another human in these stories vary, as do the age difference; Either sticking with the idea that the green, blue and red teams are close in age to Luz and her friends (canonically, the teen cast of ''Little Witch Academia'' are two years older than Luz), or going with the idea that Akko & co are an older generation, already adults by the time Luz ends up on the boiling isles.
# FriendlyFandoms.LiveActionTV: There's a far amount of crossover between the fandoms for ''Series/{{Supernatural}}'' and ''Series/DarkAngel'' owing to Creator/JensenAckles (Dean Winchester) having been on the main cast of ''Dark Angel'''s second season as Alec [=McDowell=], and Dean and Alec having comparable LovableRogue / HandsomeLech personas. It's not uncommon to find [[CommonCrossover crossover fanfics]] where either Dean and Alec are somehow the same person (despite ''Supernatural'' being set at the time it was produced and ''Dark Angel'' being TwentyMinutesIntoTheFuture) or Alec and his psychotic SerialKiller twin Ben, who was [[ActingForTwo also played by Jensen]], were cloned from Dean (since the ''Dark Angel'' characters are genetically engineered clone brothers in the first place, which makes this an ObviousCrossoverMethod). Occasionally, you get a non-paranormal AU where Ben and Alec are simply Dean and Sam's younger brothers.
# Laconic.ObviousCrossoverMethod: A FandomSpecificPlot {{Crossover}} Opportunity.
# YMMV.{{Worm}}: FandomSpecificPlot: 99% of all Worm fanfics involve Taylor obtaining a different power than in canon. This also doubles as an ObviousCrossoverMethod.
# Sandbox.LoserswithwifiPantheonStuff: [[Literature/TheFamiliarOfZero Louise Françoise le Blanc de la Vallière]], God of Popular Setups for Crossover Fanfiction (ObviousCrossoverMethod)
# YMMV.{{Amphibia}}: In the final episode, [[spoiler:Anne is offered the position as GuardianOfTheMultiverse. While she turns it down, the door is left open for her to accept once she reaches the end of her life, and popular {{Fanon}} is that she'll invite Sasha and Marcy to join her, leading to the FanficFuel of the Calamity Trio traversing different universes]].
# YMMV.DarkAngel: Crossovers with ''Series/{{Supernatural}}'' where Alec somehow became Dean Winchester (which requires a change in the time setting, since ''Supernatural'' is set in the present day and ''Dark Angel'' is set TwentyMinutesIntoTheFuture). Or where Dean was the source of Alec and Ben's DNA ([[ObviousCrossoverMethod which is more plausible]]).
# YMMV.DuckTales2017: Due to the show featuring several characters becoming superheroes, it's not uncommon with fics that cross over with ''ComicBook/PaperinikNewAdventures'' (or classic Paperinik) by having the Duck Avenger be an older or even retired hero[[note]]The first ''Paperinik'' story was published in 1969, over 20 years before ''Darkwing Duck''[[/note]] who Gizmoduck and/or Darkwing Duck look up to and admire, often with plot revolving around them finding out that Donald is the Duck Avenger.
# YMMV.EverythingEverywhereAllAtOnce: FanficFuel: The basic concept of how dimension-hopping works in this film is an easy avenue for AlternateUniverse or [[ObviousCrossoverMethod crossover fics]] where a character gains the experiences and skills of another version of themselves, or of a character from another work played by the same actor.
# YMMV.FinalDestination: Take any piece of media with an ensemble of characters. Give one of them a premonition of a horrible accident that kills them all. Have them save the others. Then Death comes for them. Presto, you have the majority of ''Final Destination'' crossover fics.
# YMMV.FiveNightsAtFreddys: Take one of the many, ''many'' works that feature a [[SuckECheeses parody of Chuck E. Cheese's]]. Now you can do a "Five Nights at X" of that (e.g. ''Five Nights at [[WesternAnimation/DextersLaboratory Chubby Cheese's]]'', ''Five Nights at [[WesternAnimation/ThePowerpuffGirls1998 Pete A. Pizza's]]'', ''Five Nights at [[WesternAnimation/InvaderZim Bloaty's]]'', ''Five Nights at [[WesternAnimation/TheSpongeBobSquarePantsMovie Goofy Goober's]]'', ''Five Nights at [[WesternAnimation/TheLoudHouse Spunk E. Pigeon's]]'', etc.).
# YMMV.{{Gate}}: FandomSpecificPlot: What if the Gate opened during a different time period (eg. During World War 1 or 2) or into a [[ObviousCrossoverMethod different universe]]?
# YMMV.HugttoPrettyCure: While ''Pretty Cure'' crossovers [[Anime/PrettyCureAllStars are nothing new]], ''Hugtto'' does stick out as it's the only ''Pretty Cure'' season to actively use {{Alternate Timeline}}s as a major plot point, while also implying that a greater [[TheMultiverse Multiverse]] is at play. Not only does the staff use this [[spoiler:to justify bringing back every previous team for a special two-parter]], but it gives the fans the perfect opportunity to crossover with other franchises as well. After all, what's stopping [[VideoGame/DragonballXenoverse2 Chronoa and the Time Patrollers]] from helping the heroes defeat Crisis Corp...?
# YMMV.InfinityTrain: FandomSpecificPlot: Crossover fics revolving around transplanting characters from other fictional works and having them traverse the train. After all, it's already from an alternate dimension, [[ObviousCrossoverMethod so why not jump through several different ones]]? Given the straightforward requirements for boarding, fans have taken to write crossovers with everything from ''WesternAnimation/TheOwlHouse'', to ''WesternAnimation/MiraculousLadybug'', to even ''Anime/PokemonTheSeries'' and ''WesternAnimation/OverTheGardenWall'', as characters from those series board the train to address their trauma and psychological issues.
# YMMV.InsideOut: FanficFuel: Take every single person, real or fictional, who has ever existed ever in the history of human kind (or even OCStandIn, your own OriginalCharacter, or, really, [[SelfInsertFic just yourself]]); what might their versions of the five emotions be like? Doubles as an ObviousCrossoverMethod.
# YMMV.{{Pibby}}: The short's status as already being a crossover, with the potential for anything connecting to it, alongside the crossover-friendly premise of "the Corruption follows Pibby to a new world and she has to team up with surviving natives to fight it", has resulted in numerous fanart depicting Pibby traveling to almost every piece of fiction people can think of, mainly of the animated kind (whether western cartoon, anime, web animation, etc.).
# YMMV.SpiderManFarFromHome: FanficFuel: The MCU is now part of a multiverse [[spoiler:actually after ''Series/Loki2021'' comes out, as Mysterio's just lying about that, of course)]], allowing for appearances of characters from the comics, non-MCU Marvel films, ObviousCrossoverMethod or really anything else you want.
# YMMV.TheMagnusArchives:
** "Character Y from Fandom X has an encounter with one of the Entities and gives a statement" is a very popular crossover fic format.
** "[Character or scary thing from other fandom] is an agent of this Entity" also gets a lot of mileage.
** [[spoiler:The final season confirms that alternate universes are a thing, and the finale has the Entities being forced into another universe--and it is ''possible'', assuming they didn't die, that Jon and Martin went with them. Cue loads of speculation about what other fictional world Jon and Martin may have been spat out in, and how that world would cope with the Entities. [[Podcast/WelcomeToNightVale Night Vale]], {{Franchise/Hatchetfield}}, and WesternAnimation/GravityFalls have all been touted as possibilities--though, of course, you could also make a case that they ended up in ''our world''.]]
# YMMV.TheOwlHouse: Crossover stories with ''Franchise/LittleWitchAcademia'' frequently has Luna Nova be another school on the Boiling Isles.
[[/folder]]
[[folder:YMMV under non-YMMV (5/54)]]
# DoppelgangerCrossover: There are several ''Supernatural'' and ''Series/DarkAngel'' crossover fics. Their ubiquity isn't surprising, as Creator/JensenAckles's characters in ''Dark Angel'', the twins Ben and Alec, were genetically engineered, and thus could conceivably be clones of Dean from ''Supernatural'' as an ObviousCrossoverMethod. '''States it's used by fans.'''
# ComicBook.MickeyMouseComicUniverse: In ''"A Mickey Mystery"'', Doctor Einmug displays an invention that lets one see what life is like on alternate Earths and later Mickey transfers to one such world. It has been argued that Doctor Einmug should be used if there is a point and not just as a vehicle for gadget, and so far the invention has only been used for a few "Disney-like" worlds. Imagine if the invention was used for other kinds of worlds as well.
# HarryPotter.TropesJToR: [Crossover character] raises Harry instead of the Dursleys might be the single most common crossover mechanism for Potter Fanfic.
# Literature.TheHeartsWeSold: The way demons work in this world makes them fit seamlessly into any previously non-magical setting. Now all your favorite characters can trade their body parts away for a wish!
# Series.{{Highlander}}: The concept means a lot of shows can generate crossover fics.
[[/folder]]
[[folder:ZCE/unclear/either/other (6/54)]]
# {{Crossover}}: ObviousCrossoverMethod: A story has an obvious method through which crossovers can occur. '''Could go either way.'''
# CrossoverRelatives: A SubTrope to RelatedInTheAdaptation and ObviousCrossoverMethod.
# FandomSpecificPlot: SailorEarth, ObviousCrossoverMethod, FukuFic, CoffeeShopAUFic, and TheShipsMotor are subtropes.
# SailorEarth: See also: SendInTheClones, ElsewhereFic, and FanCreatedOffspring. Compare ObviousCrossoverMethod.
# Fanfic.OriginStory: At first glance, this story looks like its just a GenderBender version of the run-of-the-mill standard ''{{Series/Buffy|TheVampireSlayer}}'' YAHF ("Yet Another Halloween Fanfic") plot. Except it really, really isn't. It goes off of ''those'' rails almost with the first chapter. '''Not about the means of crossover.'''
# Literature.RevolvingDoor: With universes that include RealLife, a world TwentyMinutesIntoTheFuture and just about every other type of past and future beyond, it's exceedingly easy to justify crossovers with other works. '''Can't tell if in or out of work.'''
[[/folder]]
So 17/54 (31%) are non-YMMV while 31/54 (57%) are, so a majority of examples are YMMV. A possible issue is the YMMV overlap with FanficFuel or FandomSpecificPlot.
A possible fix is to create "Crossover Catalyst" for non-YMMV uses, but that might be redundant with other tropes.
Per [[https://tvtropes.org/pmwiki/query.php?parent_id=131536&type=att ATT]], all wick (barring sandbox duplicates) have been counted (54/54).
[[folder:Non-YMMV in source material (5/54)]]
# Franchise.FateSeries: The entire concept of Servants means that it's easy to summon a crossover character as a Servant. There are even canonical examples of fictional characters being summoned, so they don't even need to be established as previously existing in the same universe. Likewise, characters from other settings starting their own Grail Wars.
# Manga.MazingerZVersusTransformers: While the Space Bridge is generally a stable method of travel in ''WesternAnimation/TheTransformers'', in the episode "Child's Play" a malfunction sent a group of Transformers to a completely different planet. For this crossover, the lead observer takes advantage of the Space Bridge's explosion to deliberately send the Transformers to Mazinger Z's world.
# MediaNotes.JennyEverywhere: Since Jenny is defined by the gimmick that there is a version of her in ''every'' reality, it is part of the premise itself that she supposedly ''already'' exists in whatever fictional universe you want to write about — ''just'' off-screen… And that's before you go into the fact that most versions of Jenny are [[DimensionalTraveler Dimensional Travelers]] who can leave their home reality at will to explore.
# TabletopGame.InfiniteWorlds: As mentioned under the Canon Welding entry, the setting itself was basically built to allow crossovers to happen by way of interdimensional travel.
# VideoGame.MortalKombat11: Kronika's Hourglass, which can bring in characters from other timelines, and is implied to be the explanation for the guest characters' appearances.
[[/folder]]
[[folder:Non-YMMV in fan material (12/54)]]
# FusionFic: ''Fanfic/{{Paradoxus}}'': The Setting Merge flavor, to be specific. [[VideoGame/WorldOfWarcraft Azeroth]] and [[WesternAnimation/WinxClub Magix]] now happen to exist in the same multi-dimensional universe. It's just they are too far apart that, ''normally'', they would've never interacted at all. Here we have Galadwen and Eudora's constant interdimensional traveling and meddling ''and'' [[spoiler: Daphne]]'s time travel shenanigans, so things are definitely not normal (more like deranged). Now, there are already some canon points that keep this idea within the realm of possibility: there are elves in both franchises, [[ObviousCrossoverMethod interdimensional traveling is confirmed and used]] in both of them, and both of them have entities capable of creating entire dimensions (the First Ones for ''World of Warcraft'' and the Great Dragon for ''Winx Club''). Though it's worth noting the Great Dragon is not equal to the First Ones, but to the Titans (like Sargeras), which helps to even out the power scales and avoid a PowerCreepPowerSeep scenario and allows for the [[TeamUpSeries teaming-up plot]] this crossover roots from.
# TropesInAggregate: ObviousCrossoverMethod '''Notes it's only a trope as a trend in works.'''
# Fanfic.ARedRoseInTheBlueWind: The story intersects the paths of both the ''Sonic'' and ''RWBY'' worlds through the Chaos Emeralds, only this time they work as intended, as opposed to the more common accident plot.
# Fanfic.CodePrime: In lieu with some traditional ''Transformers'' crossover plots, the worlds intersect through a crashed ''Ark'' and ''Nemesis''.
# Fanfic.IWannaBeTheTroll: While trying to figure out what the trollfic will be about, the AuthorAvatar decides that, since canon IWBTG is already a MassivelyMultiplayerCrossover, she can use the setting as a vehicle to send The Girl around various canons for funsies. '''An in-universe/meta example.'''
# Fanfic.MassFoundations: TeleportationMisfire: What kicked off the plot of the fic, adopting a pretty common ObviousCrossoverMethod, thus making Ethan's motivation to find a way back home, though it was a self-imposed error in improving the Transportalponder and Big Mountain being Big Mountain.
# Fanfic.{{Paradoxus}}: FusionFic: The Setting Merge flavor, to be specific. Azeroth and Magix now just happen to exist in the same multi-dimensional universe, it's just they are too far apart that, ''normally'', they would've never interacted at all. Normally. Here we have Galadwen and Eudora's constant interdimensional traveling and meddling ''and'' [[spoiler: Daphne's time travel shenanigans]], so things are definitely not normal (more like deranged). Now, there are already some canon points that keep this idea within the realm of possibility: there are elves in both franchises, [[ObviousCrossoverMethod interdimensional traveling is confirmed and used]] in both of them, and both of them have entities capable of creating entire dimensions (the First Ones for ''World of Warcraft'' and the Great Dragon for ''Winx Club''). Though it's worth noting the Great Dragon is not equal to the First Ones, but to the Titans (like Sargeras), which helps to even out the power scales and avoid a PowerCreepPowerSeep scenario and allows for the [[TeamUpSeries teaming-up plot]] this crossover roots from.
# Fanfic.PonyvilleGoesToTheDragons: Like most [=FiM=] cross-over fics, this one starts with Twilight screwing up a spell and teleporting the cross-over characters to her world. In a twist though, the spell ''was'' being performed correctly, but what happened was that Applejack ended up startling Twilight just as she was in the middle of casting the spell, causing her to jump and smudge one of the runes used in the spell. (A fact that AJ feels really guilty about.)
# Fanfic.{{Xendra}}: By using the fact characters could choose different outfits for [[Recap/BuffyTheVampireSlayerS2E6Halloween the fateful Halloween]] when Ethan Rayne [[BecomingTheCostume turned everyone into their costumes]].
# Pantheon.GamingGenresNToZ: A plethora of people Sora met across his travels are in the Pantheon, including most if not all of the Princesses of Heart he came across in his adventures. [[AllLovingHero Sora has been renown for his upbeat personality that grants him many friends across many different worlds]]. As long as you do not mess with him or are doing anything evil in front of him, Sora will extend his hand. His ability to make friends is what may be Sora's greatest asset, as he can connect with people's hearts and draws his power from those connections. That applies to people Sora may have never even met as seen with how his heart repairs a broken Ventus. [[ObviousCrossoverMethod The Pantheon opens Sora to a plethora of new worlds to explore and gain more connections]]. Sometimes, this results in Sora landing on their while a conflict he has no context for occurs. People like to point out as the Keybearer, [[AlienNonInterferenceClause Sora should not meddle in the affairs of other worlds as much as he does but Sora would like to say that it is not his fault he ends up where he goes]].
# Roleplay.CirqueMystique: The Multiverse and MutualMasquerade.
# WebAnimation.TurnaboutStorm: Naturally, Twilight messing up a spell causes Phoenix getting pulled to Equestria. [[spoiler:The twist is that the "messing up" part is a complete lie. Not only that, but TheStinger in ''Part 5'' implies that Celestia herself was the one who actually messed up the spell, getting the late Mia Fey, who later suggested Phoenix instead.]]
[[/folder]]
[[folder:YMMV (26/54)]]
# CommonCrossover: Some fandoms [[ObviousCrossoverMethod are so accessible]] that they're crossed with just about everything else. '''CommonCrossover has the same issue of if it should be YMMV, putting here as examples isn't about creator intent.'''
# FanficTropes: ObviousCrossoverMethod: A story has an obvious method through which crossovers can occur.
# FandomSpecificPlot.AnimatedFilms: "Casita creates a door/doors to elsewhere" is proving to be an ObviousCrossoverMethod.
# FandomSpecificPlot.AnimeAndManga: The show's basic premise, where Louise inadvertently summons a person from another universe during her school's Springtime Summoning Ritual, functions as an ObviousCrossoverMethod allowing her to summon anyone or anything to replace Saito. Or, alternatively, somehow mess up and send herself to the other universe: be it directly stranding herself in the new setting or being kidnapped/escorted by a resident deity or otherwise powerful entity from that world (usually as retribution for her previous attempts nearly taking someone from their world). In fact, this plot is so common that crossover fics using this framework form the majority of fanfic you'll find for the series in both its Western and Japanese fandoms.
# FandomSpecificPlot.HarryPotter: "The Late To Hogwarts Fic," in which a young wizard or witch doesn't get their invitation to Hogwarts at age 11, or is unable to go, until later age (usually when romantic plots would be more okay, so from fourth year up) — the other way is to introduce a transfer student ([[SelfInsertFic who's usually from the same country/general area and of the same background as the author]], [[WishFulfillment and is very similar to them in all aspects, only better]]). The latter type has the added benefit of 1) making up a new, totally awesome wizarding school 2) enabling the character to have a unique, totally cool wand 3) creating an explanation for [[WrongContextMagic unseen-in-Britain]], [[{{Chuunibyou}} totally super magic]] 4) allowing the character to have an inherited {{katana|sAreJustBetter}} 5) being an ObviousCrossoverMethod. Details not tying into the character's origins and entrance into Hogwarts usually follow the normal self-insert/wish-fulfillment procedure. This plot was later worked into the video game ''VideoGame/HogwartsLegacy'', which is only sorta AscendedFanon since the game itself is considered non-canon.
# FandomSpecificPlot.{{Literature}}: Many fanfics give the main character a different set of powers. This is often used as an ObviousCrossoverMethod.
# FandomSpecificPlot.{{Supernatural}}: Crossovers with ''Series/DarkAngel'' where Creator/JensenAckles's characters Ben and Alec were cloned from Dean; an ObviousCrossoverMethod, since Ben and Alec are already genetically engineered twin clones. Frequently with Dean and Sam discovering the twins as children and adopting them, thus fixing [[TykeBomb the abusive childhoods]] the twins endured in canon.
# FandomSpecificPlot.TheOwlHouse: Crossovers with ''Franchise/LittleWitchAcademia'' are common, due to both shows having a very similar premise (a {{Muggle}} with brown hair attends a school for witches and has endless romantic subtext with a green-haired witch prodigy). These stories often has [[ObviousCrossoverMethod Luna Nova be another school on the Boiling Isles]], and Luz and Akko bond over their similar struggles with magic. Wether Akko is a witch or another human in these stories vary, as do the age difference; Either sticking with the idea that the green, blue and red teams are close in age to Luz and her friends (canonically, the teen cast of ''Little Witch Academia'' are two years older than Luz), or going with the idea that Akko & co are an older generation, already adults by the time Luz ends up on the boiling isles.
# FriendlyFandoms.LiveActionTV: There's a far amount of crossover between the fandoms for ''Series/{{Supernatural}}'' and ''Series/DarkAngel'' owing to Creator/JensenAckles (Dean Winchester) having been on the main cast of ''Dark Angel'''s second season as Alec [=McDowell=], and Dean and Alec having comparable LovableRogue / HandsomeLech personas. It's not uncommon to find [[CommonCrossover crossover fanfics]] where either Dean and Alec are somehow the same person (despite ''Supernatural'' being set at the time it was produced and ''Dark Angel'' being TwentyMinutesIntoTheFuture) or Alec and his psychotic SerialKiller twin Ben, who was [[ActingForTwo also played by Jensen]], were cloned from Dean (since the ''Dark Angel'' characters are genetically engineered clone brothers in the first place, which makes this an ObviousCrossoverMethod). Occasionally, you get a non-paranormal AU where Ben and Alec are simply Dean and Sam's younger brothers.
# Laconic.ObviousCrossoverMethod: A FandomSpecificPlot {{Crossover}} Opportunity.
# YMMV.{{Worm}}: FandomSpecificPlot: 99% of all Worm fanfics involve Taylor obtaining a different power than in canon. This also doubles as an ObviousCrossoverMethod.
# Sandbox.LoserswithwifiPantheonStuff: [[Literature/TheFamiliarOfZero Louise Françoise le Blanc de la Vallière]], God of Popular Setups for Crossover Fanfiction (ObviousCrossoverMethod)
# YMMV.{{Amphibia}}: In the final episode, [[spoiler:Anne is offered the position as GuardianOfTheMultiverse. While she turns it down, the door is left open for her to accept once she reaches the end of her life, and popular {{Fanon}} is that she'll invite Sasha and Marcy to join her, leading to the FanficFuel of the Calamity Trio traversing different universes]].
# YMMV.DarkAngel: Crossovers with ''Series/{{Supernatural}}'' where Alec somehow became Dean Winchester (which requires a change in the time setting, since ''Supernatural'' is set in the present day and ''Dark Angel'' is set TwentyMinutesIntoTheFuture). Or where Dean was the source of Alec and Ben's DNA ([[ObviousCrossoverMethod which is more plausible]]).
# YMMV.DuckTales2017: Due to the show featuring several characters becoming superheroes, it's not uncommon with fics that cross over with ''ComicBook/PaperinikNewAdventures'' (or classic Paperinik) by having the Duck Avenger be an older or even retired hero[[note]]The first ''Paperinik'' story was published in 1969, over 20 years before ''Darkwing Duck''[[/note]] who Gizmoduck and/or Darkwing Duck look up to and admire, often with plot revolving around them finding out that Donald is the Duck Avenger.
# YMMV.EverythingEverywhereAllAtOnce: FanficFuel: The basic concept of how dimension-hopping works in this film is an easy avenue for AlternateUniverse or [[ObviousCrossoverMethod crossover fics]] where a character gains the experiences and skills of another version of themselves, or of a character from another work played by the same actor.
# YMMV.FinalDestination: Take any piece of media with an ensemble of characters. Give one of them a premonition of a horrible accident that kills them all. Have them save the others. Then Death comes for them. Presto, you have the majority of ''Final Destination'' crossover fics.
# YMMV.FiveNightsAtFreddys: Take one of the many, ''many'' works that feature a [[SuckECheeses parody of Chuck E. Cheese's]]. Now you can do a "Five Nights at X" of that (e.g. ''Five Nights at [[WesternAnimation/DextersLaboratory Chubby Cheese's]]'', ''Five Nights at [[WesternAnimation/ThePowerpuffGirls1998 Pete A. Pizza's]]'', ''Five Nights at [[WesternAnimation/InvaderZim Bloaty's]]'', ''Five Nights at [[WesternAnimation/TheSpongeBobSquarePantsMovie Goofy Goober's]]'', ''Five Nights at [[WesternAnimation/TheLoudHouse Spunk E. Pigeon's]]'', etc.).
# YMMV.{{Gate}}: FandomSpecificPlot: What if the Gate opened during a different time period (eg. During World War 1 or 2) or into a [[ObviousCrossoverMethod different universe]]?
# YMMV.HugttoPrettyCure: While ''Pretty Cure'' crossovers [[Anime/PrettyCureAllStars are nothing new]], ''Hugtto'' does stick out as it's the only ''Pretty Cure'' season to actively use {{Alternate Timeline}}s as a major plot point, while also implying that a greater [[TheMultiverse Multiverse]] is at play. Not only does the staff use this [[spoiler:to justify bringing back every previous team for a special two-parter]], but it gives the fans the perfect opportunity to crossover with other franchises as well. After all, what's stopping [[VideoGame/DragonballXenoverse2 Chronoa and the Time Patrollers]] from helping the heroes defeat Crisis Corp...?
# YMMV.InfinityTrain: FandomSpecificPlot: Crossover fics revolving around transplanting characters from other fictional works and having them traverse the train. After all, it's already from an alternate dimension, [[ObviousCrossoverMethod so why not jump through several different ones]]? Given the straightforward requirements for boarding, fans have taken to write crossovers with everything from ''WesternAnimation/TheOwlHouse'', to ''WesternAnimation/MiraculousLadybug'', to even ''Anime/PokemonTheSeries'' and ''WesternAnimation/OverTheGardenWall'', as characters from those series board the train to address their trauma and psychological issues.
# YMMV.InsideOut: FanficFuel: Take every single person, real or fictional, who has ever existed ever in the history of human kind (or even OCStandIn, your own OriginalCharacter, or, really, [[SelfInsertFic just yourself]]); what might their versions of the five emotions be like? Doubles as an ObviousCrossoverMethod.
# YMMV.{{Pibby}}: The short's status as already being a crossover, with the potential for anything connecting to it, alongside the crossover-friendly premise of "the Corruption follows Pibby to a new world and she has to team up with surviving natives to fight it", has resulted in numerous fanart depicting Pibby traveling to almost every piece of fiction people can think of, mainly of the animated kind (whether western cartoon, anime, web animation, etc.).
# YMMV.SpiderManFarFromHome: FanficFuel: The MCU is now part of a multiverse [[spoiler:actually after ''Series/Loki2021'' comes out, as Mysterio's just lying about that, of course)]], allowing for appearances of characters from the comics, non-MCU Marvel films, ObviousCrossoverMethod or really anything else you want.
# YMMV.TheMagnusArchives:
** "Character Y from Fandom X has an encounter with one of the Entities and gives a statement" is a very popular crossover fic format.
** "[Character or scary thing from other fandom] is an agent of this Entity" also gets a lot of mileage.
** [[spoiler:The final season confirms that alternate universes are a thing, and the finale has the Entities being forced into another universe--and it is ''possible'', assuming they didn't die, that Jon and Martin went with them. Cue loads of speculation about what other fictional world Jon and Martin may have been spat out in, and how that world would cope with the Entities. [[Podcast/WelcomeToNightVale Night Vale]], {{Franchise/Hatchetfield}}, and WesternAnimation/GravityFalls have all been touted as possibilities--though, of course, you could also make a case that they ended up in ''our world''.]]
# YMMV.TheOwlHouse: Crossover stories with ''Franchise/LittleWitchAcademia'' frequently has Luna Nova be another school on the Boiling Isles.
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# DoppelgangerCrossover: There are several ''Supernatural'' and ''Series/DarkAngel'' crossover fics. Their ubiquity isn't surprising, as Creator/JensenAckles's characters in ''Dark Angel'', the twins Ben and Alec, were genetically engineered, and thus could conceivably be clones of Dean from ''Supernatural'' as an ObviousCrossoverMethod. '''States it's used by fans.'''
# ComicBook.MickeyMouseComicUniverse: In ''"A Mickey Mystery"'', Doctor Einmug displays an invention that lets one see what life is like on alternate Earths and later Mickey transfers to one such world. It has been argued that Doctor Einmug should be used if there is a point and not just as a vehicle for gadget, and so far the invention has only been used for a few "Disney-like" worlds. Imagine if the invention was used for other kinds of worlds as well.
# HarryPotter.TropesJToR: [Crossover character] raises Harry instead of the Dursleys might be the single most common crossover mechanism for Potter Fanfic.
# Literature.TheHeartsWeSold: The way demons work in this world makes them fit seamlessly into any previously non-magical setting. Now all your favorite characters can trade their body parts away for a wish!
# Series.{{Highlander}}: The concept means a lot of shows can generate crossover fics.
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# {{Crossover}}: ObviousCrossoverMethod: A story has an obvious method through which crossovers can occur. '''Could go either way.'''
# CrossoverRelatives: A SubTrope to RelatedInTheAdaptation and ObviousCrossoverMethod.
# FandomSpecificPlot: SailorEarth, ObviousCrossoverMethod, FukuFic, CoffeeShopAUFic, and TheShipsMotor are subtropes.
# SailorEarth: See also: SendInTheClones, ElsewhereFic, and FanCreatedOffspring. Compare ObviousCrossoverMethod.
# Fanfic.OriginStory: At first glance, this story looks like its just a GenderBender version of the run-of-the-mill standard ''{{Series/Buffy|TheVampireSlayer}}'' YAHF ("Yet Another Halloween Fanfic") plot. Except it really, really isn't. It goes off of ''those'' rails almost with the first chapter. '''Not about the means of crossover.'''
# Literature.RevolvingDoor: With universes that include RealLife, a world TwentyMinutesIntoTheFuture and just about every other type of past and future beyond, it's exceedingly easy to justify crossovers with other works. '''Can't tell if in or out of work.'''
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So 17/54 (31%) are non-YMMV while 31/54 (57%) are, so a majority of examples are YMMV. A possible issue is the YMMV overlap with FanficFuel or FandomSpecificPlot.
A possible fix is to create "Crossover Catalyst" for non-YMMV uses, but that might be redundant with other tropes.
