|Tropes and genres|
|Related tropes/genres||pastiche, crossover, AU|
|See also||multiverse, fusion (trope)|
|Related articles on Fanlore.|
A fusion is a type of fanwork which incorporates elements of two or more fandoms in an integrated or composite work. These elements may include characters, settings, background material, and/or plot details.
This term was somewhat known around the year 2000, but not as common as it would be in other years of the 2000s decade until its further popularization by Liviapenn in 2005, when she created the sga_fusion community to support the Atlantis Amalgamated challenge. Since the challenge was centered in the Stargate Atlantis fandom, many of the stories identified as 'fusions' come from that fandom.
Fusion vs. Crossover vs. AU
Discussion is ongoing as to the relationship between fusions, crossovers and AUs. Some regard fusions as a subset or specialized form of crossover, whereas others consider fusions a parallel form, describing crossovers as works where multiple source canons temporarily intersect but remain essentially independent. Alternately, it’s possible to look at all fusions as essentially AU in nature, or to assert that some serve merely as extensions to one or all of their source canons.
I think fusions are generally considered a subcategory of crossovers. A crossover is any fic where two fandoms interact, but a fusion has to have major AU elements to make them fit together. The distinction can get a little fuzzy sometimes, but generally a fic is pretty clearly one or the other.
Themed AU's like daemon AU's, Sentinel AU's, Pern AU's, etc, are all going to be fusions. Fics where the cast of one fandom take on the roles of another fandom (everyone is now Hogwarts students and teachers, and one of the characters is the new boy-who-lived) are all fusions. Fics where one cast of characters is majorly modified to fit into the world-building of another fandom are also fusions, like if the cast of fandom A are now all Hogwarts students, but Harry Potter graduated five years ago and Flitwick still teaches Charms.On the other hand, most fics where a character from fandom A goes through a magical portal or something and ends up in fandom B are non-fusion crossovers. 
Where the source canons involved in a particular fanwork share common elements, the question of crossover vs. fusion may be a matter of degree. For example, since both Castle and the Law & Order franchise are set in New York City and involve law enforcement, simply introducing the two casts of characters to one another isn’t difficult. However, if a fan author chooses to have Rick Castle shadow L&O detective Nina Cassidy rather than Kate Beckett, or to insert Beckett into L&O:SVU in place of Detective Olivia Benson, the resulting work is clearly more fusion than crossover.
The premise and/or narrative structure of some source canons lend themselves well to adaptation as fusions. For example, Stargate:SG-1 – in which the tight secrecy surrounding the Gate program is a core component of the series premise – can be easily fused with fandoms such as NCIS or The Sentinel. Alternately, the “catch-all” nature of the supernatural elements in Buffy the Vampire Slayer and Supernatural makes either of these canons easy to fuse with each other, or with nearly any other magic-intensive canon (say, Teen Wolf or the Mercy Thompson books by Patricia Briggs).
Characters from one fandom are depicted as if they were native to an entirely different fandom. In general, the setting is depicted consistently with its source media. For example, a Pern Fusion would cast characters from a different source material as Dragonriders of Pern. There are also Harry Potter stories where non-HP characters attend Hogwarts, and Star Wars stories where non-SW characters are placed in the Star Wars galaxy
- Pokemon Crossing: Fly Me to the Moon: follows Animal Crossing characters in the Pokemon world
An object, artifact, or character from one fandom is transposed to another fandom, while retaining its (or their) original nature or personality.
- Calvin & Hobbes - Calvin gets a Green Lantern power ring
- Elsinore by Malkin Grey - Sam & Dean Winchester investigate ghostly manifestations in Hamlet
- Buffy the Pony Vampire Slayer - fusion art by Michelle Leal (Buffy/My Little Pony: Friendship is Magic)
- Untitled - fusion art by Vanessa Naylon (Star Trek: The Next Generation/Harry Potter)
- Young Wizards (Diane Duane) - an extra-canonical character is a wizard or gets a wizard's manual
Transposed Premise (including <Fandom> AU)
The central conceit of one fandom (i.e. Immortals, kaiju, soulbonds) is applied to the characters and setting of another fandom. If sufficiently popular, the set of works arising from a specific iteration of this subtype may be described as an AU of the original fandom (i.e. a Sentinel AU).
Popular Fusion/AU Fandoms
- Highlander - One or more characters are Immortals
- His Dark Materials - Humans have dæmons 
- Leverage - Characters form a Leverage-style team
- Pacific Rim - Characters are Jaegar pilots
- Sentinel - Characters have a fanon Sentinel-Guide soulbond; often set in a darkfic AU
- A Heartbeat At My Feet by Kellifer_fic (Supernatural/His Dark Materials)
- Inclination by jacquez - (Sentinel/Star Trek)
- The Old Testament Job by archea2. (Leverage/Pride and Prejudice).
- The Breakfast Club - Characters re-enact the plot of the movie.
- A Christmas Carol - A non-Dickens character is given the Scrooge treatment.
Merged Setting/Canon Characters
Two or more fandoms are portrayed as existing side-by-side in a more or less integrated setting, with all or most characters from each fandom retaining their original identities/roles. Where elements of the original settings may conflict, the work generally attempts to reconcile the differences rather than unilaterally adopting one source’s canon over the other.
- Night Watch by Brighid (Sentinel/Batman) 
- The Phantom Rangers by Random_Nerd3 (Julie & the Phantoms/Power Rangers)
- Scion of Musagetes by Jedi Buttercup (Castle/Percy Jackson)
- you can hardly blame him for wanting to send backup by Jedi Buttercup (BtVs/SG-1)
Elements of two or more fandoms are combined to produce a composite setting. The resulting work will often include characters and/or settings created by merging aspects of each source’s into composites. (Comics fandom labels this subtype as an amalgam. )
- Charlotte Holmes in the 22nd Century by Gray Cardinal (Charlotte Holmes/Sherlock Holmes in the 22nd Century)
- Detective al Ghul by Marcus_S_Lazarus (Batman(Nolanverse)/Castle)
- Serenity, Nevada by Christina K (Buffy/Firefly)
Same Actor Fusion
Similar to a Same Actor Crossover, but rather than the characters being doubles for one another, they're merged into a unified composite character. These fusions often incorporate elements of other subtypes as well. Footage of different characters played by the same actor is sometimes used in fanvids, gifs and other fanart to develop the illusion of the composite identity.
- Doctor Who and Life On Mars
- The Master and Sam Tyler.
- Sherlock (BBC) and The Hobbit
- Sherlock (BBC) and Different For Girls
- Rupert Graves characters Detective Inspector Lestrade and Paul Prentice have been fused by sadynax and others. Paul Prentice is perhaps the inspiration for the Inspector's fanon leather jacket, motorcycle and appreciation for punk music.
Heavens are Infinite
This is a type of fusion popular among wuxia and xianxia writing communities in China and Taiwan. Often, these have a connected setting merging the worlds of other preexisting series together with other original worlds and/or reality-warping cultivators who travel between them in a large multiverse.
Other Example Fanworks
- Blade Runner by newkidfan, a vid merging Merlin characters with the Blade Runner universe
- Merlin Fan Made Opening Credits Game of Thrones Style
Recs & Thematic Lists
- David Leroy Lindquist Jr. (1998-04-24) (FF) Final Victory, although this does not appear to be a fusion but merely mentions some
- RatCreature. How to construct Alternate Universes that work as fanfic. Originally posted to FCA-L on 28 January 2001. (accessed 6 November 2008)
- As seen with results on FanFiction.net.
- Atlantis Amalgamated: the fusion universe Accessed November 6, 2008
- Comment by u/pointysparkles on Reddit thread Can someone explain to me the difference between crossover and fusion?, July 2019
- "The thing is, AUs aren't copy/pastes of movie transcripts. Can an author lift dialogue? Sure. Lift scenes and circumstances? Absolutely. Does an author have to explain the characters and how they feel in that situation? Yes. [...] And that's the the thing about AUs: they're work. You have to know what you're saying about the characters and there has to be something deeper there. screamlet and leupagus and I have spent hours talking about it over the course of writing Legends and Spoctoria and even Dr. Princess -- these characters don’t exist in vacuums, and even when you put them in space operas, they're still them with defined character traits and baggage. You have to respect that and then tell the story from there. [...] An AU is not an excuse to write OOC. Otherwise you're just parroting back the film (and I can watch that)." from ON THE SUBJECT OF MOVIE AUs/FUSIONS (No, Really, Apparently This Needs To Be Said), Archived version, essay by waldorph, 11 January 2011. (Accessed 11 April 2011)
- Some fandoms are defined more by their fusion potential than by fannish activity in-universe alone; His Dark Materials is a good example, with whole livejournal comms being devoted to the genre.
- A Heartbeat At My Feet. Posted 22 January 2008, accessed 07 November 2008. Sam and Dean have dæmons.
- Inclination by Jacquez. Posted 27 May 2001. (Accessed 7 November 2008). Blair is a straight Vulcan Guide with his own secret reasons to want to bond with Sentinel Starfleet Captain Jim Ellison.
- Posted Sept. 5, 2022. The ladies of P&P join forces to provide BEVERAGE.
- Brighid. . Posted 4 September 2000. (Accessed 7 November 2008)
- "It's a little easier to talk about this type of thing in comics fandom, where there's a clear-cut difference between a crossover and an amalgam-- every so often DC and Marvel will get together and do an "Amalgam" comic, where two universes are squished together resulting in something like Sparrow, who is a squished-together version of Robin and Jubilee.) Anyway, that's what these stories should be-- not crossovers where Angel or Jim Ellison or Horatio Hornblower or Remus and Sirius suddenly discover the existence of Atlantis, but one where they've been there this whole time, as Marines, or scientists, or Athosians, or whatever. Where they've become part of a team, just as they are in their original fandoms. NEW CHALLENGE: ATLANTIS AMALGAMATED" Accessed November 6, 2008}}
- 2008 accessed 27th June 2015. A fusion set in a small Nevada town where the Serenity characters are Sheriff (Mal), Mayor (Inara), etc., someone is killing the residents, and wandering rock musician Oz arrives on the trail.
- ** This fusion began being drawn and written when it was announced the Benedict Cumberbatch had been cast along side his Sherlock co-star Martin Freeman as the dragon Smaug in The Hobbit. The portmanteau names "Smauglock" and "Johnbo" refer to the Smaug/Sherlock fusion and John/Bilbo fusion characters respectively.
- ääärrr by Sadynax