What Does Fusion Mean?
Fic TypeAn AU that pours one canon's characters into another canon's world — the crew reimagined inside the Hogwarts system, the detectives in the Pacific Rim universe. One cast, another world's rules.
Fusion in Practice
The fusion is the crossover's elegant sibling: instead of two casts meeting, one fandom's characters are translated into another fandom's setting, usually without the second canon's characters existing at all. The form's pleasure is structural rhyme — discovering which character is obviously the dragon rider, which house the team sorts into, who pilots the jaeger with whom — and the best fusions use the borrowed world's machinery to say something true about the imported characters. Certain settings proved so fusion-friendly they became standard templates: Hogwarts AUs, daemon AUs, soulmate-mechanics worlds, and sentinel-and-guide dynamics all function as shared infrastructure any fandom can borrow. Fandom distinguishes fusion from crossover with reasonable consistency, though the tags blur at the edges and many works announce themselves simply as '[Other Canon] AU.'
Example usage
"It is a fusion where the heist crew are Pacific Rim pilots, and the drift-compatibility reveal is exactly the metaphor you think."
Related Terms
Crossover
A fic that combines two or more separate canons, bringing their characters and worlds into contact — the detective meets the wizard, the starship picks up the time traveler. Distinct from a fusion, where one cast is placed inside another's world.
Definition →
AU (Alternate Universe)
Short for Alternate Universe: a story that deliberately changes fundamental facts of the canon setting — the time period, the world's rules, or the characters' circumstances. Coffee shop AUs, no-powers AUs, and modern AUs are classic examples.
Definition →
Daemon AU
An alternate universe borrowing the daemon concept from Philip Pullman's His Dark Materials: every person's soul lives outside their body as an animal companion. Any fandom's cast can be reimagined with daemons.
Definition →
Hogwarts AU
A fusion AU placing another fandom's characters in the Hogwarts setting — sorted into houses, attending classes, playing Quidditch. One of fandom's standard borrowed-world templates.
Definition →
Soulmate AU
An AU built on a universe where soulmates demonstrably exist, marked by some mechanism — a name on your skin, shared pain, color vision unlocking at first touch. The mechanic varies; the destiny is the genre.
Definition →
Read fanfiction on the go
Fanfict Reader is the best way to browse, search, and read AO3 fanfiction on your iPhone. Download for free and start reading your favorite stories today.