History SoYouWantTo / WriteACrossover

* CelebrityParadox - of a sort; a lot of crossovers hinge on the fact that several characters (who are, of course, portrayed by the same performer) look rather alike, which enables them to find links between them; for example, perhaps [[Series/{{Castle}} Richard Castle]] is a direct ancestor of [[{{Firefly}} Malcolm Reynolds]]?[[note]]Both characters are played by NathanFillion, in case you didn't know.[[/note]]

Depending on how often you're engaging in the crossover, ContinuityLockout can be a problem. As mentioned above, not everyone in the audience is going to be familiar with or even know both properties that are being crossed over, and not everyone in your audience for a particular series is going to enjoy or read crossovers. This means that not only do you have to be careful in using continuity in the crossover itself (so that the audience can reasonably follow what is going on without needing to be intimately familiar with everything in both properties), but if the crossover is part of a larger series you also need to be careful when referring back to it. For example, a plot element originally introduced on the show ''Series/{{Angel}}'' was transferred to the characters of ''BuffyTheVampireSlayer'' via a crossover, where it ended up being vitally important in the final episode of the latter series. All very well, since both shows inhabited a SharedUniverse -- except that even with this being the case, not everyone who watched the latter also watched the former, meaning that as far as those who ''didn't'' watch both were concerned the crossover element ended up being a DeusExMachina. Of course, you can expect a certain percentage of the audience to watch both shows, but you cannot reasonably expect ''everyone'' to do so, and by using the crossover in this way you risk pissing off the people who don't -- which can be a problem if the audience for both shows has less overlap than you initially think.

* The [[PoliceProcedural police procedurals]] ''HomicideLifeOnTheStreet'' and ''LawAndOrder'' crossed over so frequently that after Homocide ended, Det. JohnMunch actually became a character on ''[[LawAndOrderSpecialVictimsUnit Law & Order:SVU]].''

On the other hand, props should usually be limited to those held in common with the focus series and/or the neutral setting. i.e. [[TheLordOfTheRings Frodo Baggins]] and [[HannahMontana Miley Cyrus]] should not be handling [[{{Digimon}} Digivices]] unless that series is ''also'' involved [[FusionFic in some way]].

Crossovers can be a really fun kind of fiction to write; there's something really appealing in imagining fictional characters from numerous different properties interact in one story; how would they interact? Would they gel or collide?

* One of the most basic is a Dimensional Crossover: Each series involved is in their own dimension, with some kind of travel (accidental or intentional) or NegativeSpaceWedgie bringing them together. In these cases, a good portion of the story is usually involving how to get the character(s) who are out of time and out of place back to where they belong. '''Example''': Most crossover stories between MarvelComics and DCComics are done this way.
* Another common type is the Temporal Crossover: When the series' involved take place in different time periods, you may choose to say that they take place in the same universe, just at different points along the timeline. Works by the same author may have this be true officially. '''Example''': The MarvelCinematicUniverse: ''Film/CaptainAmericaTheFirstAvenger'' happened in the 1940's, while the ''Film/IronMan'' films take place in the present.
* Adjacent Crossovers are usually what happens when the series' involved take place in the same universe and at the same time. Distance, focus, and circumstances simply kept the two apart, until now. '''Example''': the various {{Interconinuity Crossover}}s and guest appearances between different books of Marvel Comics (or DC). SpiderMan and the ComicBook/Avengers both live in New York City of the same universe and generally do their own thing, but sometimes circumstances put them together to save the day.
* A Fusion or Merged crossover is usually restricted to the likes of Fan Fiction and Alternate Universes: where the series' are brought together so closely that elements become mixed together and/or replace each other. '''Example''': The UltimateMarvel universe (about the only official version of this there is) is a lot more intertwined between titles than the normal Marvel Universe. The fan fics ''{{FanFic/Renegade}}'' and ''FanFic/ProtocultureEffect'' both replace the [[MassEffect SystemsAlliance]] with the Human forces of another Sci-Fi series.

How will the crossover affect the series' involved? Will this be a one-shot that leaves the Status Quo of each series mostly untouched, or will there be ongoing effects that change everyone involved (for good or ill)?

Depending on how often you're engaging in the crossover, ContinuityLockout can be a problem. As mentioned above, not everyone in the audience is going to be familiar with or even know both properties that are being crossed over, and not everyone in your audience for a particular series is going to enjoy or read crossovers. This means that not only do you have to be careful in using continuity in the crossover itself (so that the audience can reasonably follow what is going on without needing to be intimately familiar with everything in both properties), but if the crossover is part of a larger series you also need to be careful when referring back to it. For example, a plot element originally introduced on the show ''{{Angel}}'' was transferred to the characters of ''BuffyTheVampireSlayer'' via a crossover, where it ended up being vitally important in the final episode of the latter series. All very well, since both shows inhabited a SharedUniverse -- except that even with this being the case, not everyone who watched the latter also watched the former, meaning that as far as those who ''didn't'' watch both were concerned the crossover element ended up being a DeusExMachina. Of course, you can expect a certain percentage of the audience to watch both shows, but you cannot reasonably expect ''everyone'' to do so, and by using the crossover in this way you risk pissing off the people who don't -- which can be a problem if the audience for both shows has less overlap than you initially think.

* CelebrityParadox - of a sort; a lot of crossovers hinge on the fact that several characters (who are, of course, portrayed by the same performer) look rather alike, which enables them to find links between them; for example, perhaps [[{{Castle}} Richard Castle]] is a direct ancestor of [[{{Firefly}} Malcolm Reynolds]]?[[hottip:*:Both characters are played by NathanFillion, in case you didn't know.]]

One common link that makes crossovers easier to manage is if all involved franchises take place within the same basic location; it is, after all, easy to accept that characters from one franchise set in London might conceivably encounter characters from another which is also set in that city. If this is not an option, then a choice might have to be made about which franchise is going to be placed into the 'world' of the other. Depending on what the franchises are, this might be an easy choice -- a property in which the main characters are WalkingTheEarth means that they can conceivably walk into a property which is bound to one location and then walk away again when the story is done.

The PlotTailoredToTheParty usually comes into play here; since the point of a crossover is to see the characters interact, this usually means that each character will get a chance to show off their usual skills or {{Iconic Item}}s. Also, Technology / {{Magitek}} from series A handled by characters from Series B is usually good for some laughs.

Usually, most crossovers don't have to think about costumes, as the standards of the Location take precedence, followed by the characters' ordinary LimitedWardrobe. However, a humorous (or {{FanService}}y) moment can be had when certain characters have to dress in a certain way, usually either to fit in with the aforementioned setting, or as a visual ActorAllusion.[[hottip:*:Other [[CostumeTropes reasons]] for dressing up are handled just as well in other genres.]] If the crossover author ''does'' have reason to expand wardrobes, one must take '''great''' care to avoid CostumePorn.

On that note, the caution against the StoryBreakerTeamUp stands. However, this does not mean that, e.g. [[{{Dragonball}} Mr. Satan]] can't fight [[Series/StarTrekTheNextGeneration Worf]] in hand-to-hand; it just means that, e.g. [[SupermanStaysOutOfGotham Goku stays off the Enterprise]]. These such limitations can also allow for ADayInTheLimelight for characters that normally have less focus. But don't give such characters [[PossessionSue too much focus/power]]...

* The [[PoliceProcedural police procedurals]] ''[[HomicideLifeOnTheStreet Homicide: Life on the Street]]'' and ''LawAndOrder'' crossed over so frequently that after Homocide ended, Det. JohnMunch actually became a character on ''[[LawAndOrderSpecialVictimsUnit Law & Order:SVU]].''
* [[FightingGame Fighting games]] in which characters from different franchises - or even [[MarvelVsCapcom different companies]] - fight each other are commonplace. But ''VideoGame/MortalKombatVsDCUniverse'' actually took the rare step of coming up with a story mode and with a plot that explains ''how'' and ''why'' the characters are fighting each other, and even goes the extra mile of explaining why characters like {{Superman}}, TheJoker, Liu Kang, and Raiden are having fist fights [[PowerCreepPowerSeep on equal footing]].

* ''SuperRobotWars''. Each game takes numerous HumongousMecha anime, [[WorldBuilding creates a whole new world where they can coexist]], ties the original plots together (changing some plot devices if needed), and takes a look at [[AllThereInTheManual unused materials (including model kits and novel adaptions)]] to see if there is something that can be used. The result is usually good.

* The novel ''Planet X'' is an officially published (though almost certainy out of [[{{Canon}} continuity]]) crossover between the XMen and ''Series/StarTrekTheNextGeneration''. [[BetterThanItSounds Not as bad as it sounds.]] (And, yes, it mentions [[PatrickStewart the uncanny resemblance between Xavier and Picard]]... despite being published ''before'' the movie was cast!).

Certain properties may also lend themselves more to being crossed over than others, which can effect the story being crafted. To take one example, ''Series/DoctorWho'' is a property that lends itself particularly well to being crossed over with others -- the TARDIS can literally land anywhere in time and space and do anything, enabling the writer to engage with a wide-range of genres, mediums, moods and properties; all a writer really has to do to effect a crossover is plonk the TARDIS down in a particular location and have the Doctor wander around until he meets the other characters. Other properties, however, may not have the luxury of this kind of freedom for writers, being tied to a particular genre, setting, theme, etc; it would take a lot more work to effect a successful crossover wherein characters from ''TheWire'' found a starship and travelled the galaxy until they met the [[StarTrek USS Enterprise]] because the shows are quite different in genre, tone, setting, etc. Successful crossovers are aware of these limitations and manage to effectively overcome them.

* '''Overlapping Adventures''': A smaller scale version of the Ultimate Showdown where the characters from one franchise happen to be working on the same (or a similar) problem to the characters from another franchise, only for the two to eventually collide; for example, Detectives Briscoe and Logan from ''LawAndOrder'' might be investigating a murder only for Agents Mulder and Scully from ''TheXFiles'' to be investigating the same crime, or the crew of the [[StarTrek USS Enterprise]] might be investigating a suspicious phenomenon on a distant planet while at the same time [[Series/DoctorWho the TARDIS]] has arrived there. Official crossovers on a smaller scale to the Ultimate Showdown might use this.

On that note, the caution against the StoryBreakerTeamUp stands. However, this does not mean that, e.g. [[{{Dragonball}} Mr. Satan]] can't fight [[StarTrekTheNextGeneration Worf]] in hand-to-hand; it just means that, e.g. [[SupermanStaysOutOfGotham Goku stays off the Enterprise]]. These such limitations can also allow for ADayInTheLimelight for characters that normally have less focus. But don't give such characters [[PossessionSue too much focus/power]]...

* The novel ''Planet X'' is an officially published (though almost certainy out of [[{{Canon}} continuity]]) crossover between the XMen and ''StarTrekTheNextGeneration''. [[BetterThanItSounds Not as bad as it sounds.]] (And, yes, it mentions [[PatrickStewart the uncanny resemblance between Xavier and Picard]]... despite being published ''before'' the movie was cast!).
** The novel [[AlternateContinuity contains references]] to comics that were published in which various groups of X-Men met characters from the StarTrek universe, including the cast of the original show.

* EigenPlot- Similarly, expect both heroes to get the chance to show off their abilities.

The EigenPlot usually comes into play here; since the point of a crossover is to see the characters interact, this usually means that each character will get a chance to show off their usual skills or {{Iconic Item}}s. Also, Technology / {{Magitek}} from series A handled by characters from Series B is usually good for some laughs.

One common link that makes crossovers easier to manage is if all involved franchises take place within the same basic location; it is, after all, easy to accept that characters from one franchise set in London might conceivably encounter characters from another which is also set in that city. If this is not an option, then a choice might have to be made about which franchise is going to be placed into the 'world' of the other. Depending on what the franchises are, this might be an easy choice -- a property in which the main characters are WalkingTheEarth means that they can conceivably walk into a property which is bound to one location and then walk away again when the choice is done.

* [[FightingGame Fighting games]] in which characters from different franchises - or even [[MarvelVsCapcom different companies]] - fight each other are commonplace. But ''VideoGame/MortalKombatVsDCUniverse'' actually took the rare step of coming up with a story mode and with a plot that explains ''how'' and ''why'' the characters are fighting each other, and even goes the extra mile of explaining why characters like {{Superman}}, TheJoker, Liu Kang, and Raiden are having fist fights [[PowerCreepPowerSeep on eqaul footing]].

The EigenPlot usually comes into play here; since the point of a crossover is to see the characters interact, this usually means that each character will get a chance to show off their usual skills or {{Iconic Item}}s.

* [[FightingGame Fighting games]] in which characters from different franchises - or even [[MarvelVsCapcom different companies]] - fight each other are commonplace. But ''MortalKombatVsDCUniverse'' actually took the rare step of coming up with a story mode and with a plot that explains ''how'' and ''why'' the characters are fighting each other, and even goes the extra mile of explaining why characters like {{Superman}}, TheJoker, Liu Kang, and Raiden are having fist fights [[PowerCreepPowerSeep on eqaul footing]].

* The novel ''Planet X'' is an officially published (though almost certainy out of [[{{Canon}} continuity]]) crossover between the XMen and ''StarTrekTheNextGeneration''. Not as bad as it sounds. (And, yes, it mentions the uncanny resemblance between Xavier and Picard ... despite being published ''before'' the movie was cast!).

* ''TheLeagueOfExtraordinaryGentlemen'', both in comic and film format, is a rare example of an officially published MassiveMultiplayerCrossover (it helps that most of the central characters are from works that are at least OlderThanRadio, if not older, and thus exist in the [[PublicDomainCharacter public domain]]; works which aren't tend to be alluded to in dialogue), wherein practically every detail is taken from another work in an attempt to put together a cohesive fictional universe for all (or at least as close to all as possible) of human storytelling. The comic is by AlanMoore and Kevin O'Neal and is well worth a look.
* ''KingdomHearts'' took two works that sounded as if they definitely ''should not'' be crossed with each other and managed to make the final result ''great''.

* CelebrityParadox - of a sort; a lot of crossovers hinge on the fact that several characters (who are, of course, portrayed by the same performer) look rather alike, which enables them to find links between them; for example, perhaps Richard {{Castle}} is a direct ancestor of [[{{Firefly}} Malcolm Reynolds]]?

Certain properties may also lend themselves more to being crossed over than others, which can effect the story being crafted. To take one example, ''DoctorWho'' is a property that lends itself particularly well to being crossed over with others -- the TARDIS can literally land anywhere in time and space and do anything, enabling the writer to engage with a wide-range of genres, mediums, moods and properties; all a writer really has to do to effect a crossover is plonk the TARDIS down in a particular location and have the Doctor wander around until he meets the other characters. Other properties, however, may not have the luxury of this kind of freedom for writers, being tied to a particular genre, setting, theme, etc; it would take a lot more work to effect a successful crossover wherein characters from ''TheWire'' found a starship and travelled the galaxy until they met the [[StarTrek USS Enterprise]] because the shows are quite different in genre, tone, setting, etc. Successful crossovers are aware of these limitations and manage to effectively overcome them.

* '''Overlapping Adventures''': A smaller scale version of the Ultimate Showdown where the characters from one franchise happen to be working on the same (or a similar) problem to the characters from another franchise, only for the two to eventually collide; for example, Detectives Briscoe and Logan from ''LawAndOrder'' might be investigating a murder only for Agents Mulder and Scully from ''TheXFiles'' to be investigating the same crime, or the crew of the [[StarTrek USS Enterprise]] might be investigating a suspicious phenomenon on a distant planet while at the same time [[DoctorWho the TARDIS]] has arrived there. Official crossovers on a smaller scale to the Ultimate Showdown might use this.

LetsYouAndHimFight can be a bit hackneyed, since it's a slightly cliched way of creating tension between the characters; perhaps in your crossover the characters could have a moment's friction, but actually decide to work together from the start?

* ''SuperRobotWars'' . Each game take numerous HumongousMecha anime, [[WorldBuilding creat whole new world where they can coexist]], tie the original plots together (change some plot devices if need), take a look at [[AllThereInTheManual unused materials (including model kit and novel adaption)]] to see if there is something can be use. The result is usually good.

Official crossovers are tricky, because so many fictional properties are owned by a wide range of corporate media interests, often giving rise to tangled and / or complex issues of copyright in the process. On the most simple level, you rarely see certain properties come together officially because different corporations own them; you rarely see Comicbook/SpiderMan and Comicbook/{{Batman}} hanging out because one is owned by Marvel and the other DCComics, and the DC writers don't have the right to use SpiderMan in their stories. Of course, on certain occasions the two have and can be brought together, but it's usually very rare and depends on the interest and goodwill of all copyright owners. And that's when the issue of copyright is clear-cut; certain characters exist within a legal quagmire of copyright issues.

* CelebrityParadox - of a sort; a lot of crossovers hinge on the fact that several characters (who are, of course, portrayed by the same performer) look rather alike, which enables them to find links between them; for example, perhaps Richard {{Castle}} is a direct descendant of [[{{Firefly}} Malcolm Reynolds]]?

* '''Two Guys Walk Into A Bar''': A crossover which centres around two (or more) characters who just happen, for whatever reason, to cross paths over the course of their day-to-day lives. Often done on a smaller scale than the Overlapping Adventures, and usually the hallmark of shorter works of fanfiction. The typical example tends to involve a character from one franchise going into a bar at the end of their day and striking up a conversation with whoever they end up sitting next to, who turns out to be a character from another franchise. The focus is usually on CharacterDevelopment and Character Exploration, usually centred around VillainsOutShopping or HeroesGoneFishing; how do these two characters spark off each other? Naturally, it doesn't ''have'' to be a bar, but it's generally just some similar small, every day activity which throws these two together rather than a crisis as above (although the crisis might form the background to the story).

Assuming copyright permission -- or alternatively, you're writing an unofficial fanfiction without seeking it out -- certain inherent issues within the story become apparent. When you're bringing together characters from different properties, you have to consider that these characters often have different fanbases, frequently comprising people who are fans of one but not the other. This means you have to be careful when introducing and using both properties, because chances are good that you will be aiming at an audience of which a good part will have no idea who the other character / property is. Of course, this can depend on the genre that's being brought together -- if you're bringing together two mainstream superhero properties, then it's perhaps fair to say that most of your readers will have heard of and will be able to identify both Batman and Spider-Man -- but if you're bringing together two different mediums or genres, you have to be wary of treating the characters as if everyone can identify them. This is especially the case if one property is more obscure than the other. You will need to ensure that you identify and characterise them clearly so that newcomers will at least be able to gain a sense of who they are.

* ''[[JlaAvengers JLA/Avengers]]'' gets right everything that ''Marvel vs DC'' (see below) gets wrong. Both franchises are respected right down to established differences in each universe's physics and geography being acknowledged. The difference in power levels between the universes is incoporated into the story instead of being handwaved aside. The story even dares to admit that certain characters would easily defeat others while allowing some of them to be smart enough to ''not'' fight for no reason.

* Whilst ''TheLeagueOfExtraordinaryGentlemen'' in comic form is widely agreed to belong in the 'Greats' category, most would put the movie based on same squarely in the 'Epic Fails' column. Not only does it water down and dilute the original, it's also in many ways quite a poorly-told story.

* The novel ''Planet X'' is an officially published (though almost certainy out of [[{{Canon}} continuity]]) crossover between the XMen and ''StarTrekTheNextGeneration''. Not as bad as it sounds. (And, yes, it mentions the uncanny resemblence between Xavier and Picard ... despite being published ''before'' the movie was cast!).

* The novel ''Planet X'' is an officially published (though almost certainy out of [[{{Canon}} continuity]]) crossover between the XMen and ''StarTrekTheNextGeneration''. Not as bad as is sounds (and, yes, in mentions that Xavier and Picard look alike ... despite being published before the movie was cast!).

Whilst ''TheLeagueOfExtraordinaryGentlemen'' in comic form is widely agreed to belong in the 'Greats' category, most would put the movie based on same squarely in the 'Epic Fails' column. Not only does it water down and dilute the original, it's also in many ways quite a poorly-told story.

* ''TheLeagueOfExtraordinaryGentlemen'', both in comic and film format, is a rare example of an officially published MassiveMultipleCrossover (it helps that most of the central characters are from works that are at least OlderThanRadio, if not older, and thus exist in the PublicDomain; works which aren't tend to be alluded to in dialogue), wherein practically every detail is taken from another work in an attempt to put together a cohesive fictional universe for all (or at least as close to all as possible) of human storytelling. The comic is by AlanMoore and Kevin O'Neal and is well worth a look.

* '''Two Guys Walk Into A Bar''': A crossover which centres around two (or more) characters who just happen, for whatever reason, to cross paths over the course of their day-to-day lives. Often done on a smaller scale than the Overlapping Adventures, and usually the hallmark of shorter works of fanfiction. The typical example tends to involve a character from one franchise going into a bar at the end of their day and striking up a conversation with whoever they end up sitting next to, who turns out to be a character from another franchise. The focus is usually on CharacterDevelopment and Character Exploration, usually centred around VillainsOutShopping or HeroesOutFishing; how do these two characters spark off each other? Naturally, it doesn't ''have'' to be a bar, but it's generally just some similar small, every day activity which throws these two together rather than a crisis as above (although the crisis might form the background to the story).

!'''Costume Designer'''