Headcanon is a term, used in fanfiction, when a person ads his or her personal beliefs and flairs into the story, presenting it as canon in his or her own head.
This is rather common in fanfictions, although “headcanons” sometimes grow in popularity and get adopted by several people, or groups, turning the idea into fanon which may go as far as getting adopted into the canon altogether.
Canon in fiction is something that refers to a set of places, plotlines, characters and relationships within the universe of a fictional world, that had been established by the original authors themselves, in the source work.
The word canon comes from a 1911 essay of Ronald Knox who distinguished the “canon” stories, written by Sir Arthur Conan Doyle, from those of his fans.
The first time “headcanon” appeared online was in an author’s notes on LiveJournal in 2007.
The term here is used to explain the conclusions and personal opinions of the author, as she tried to make sense of the canon with her own beliefs and ideas.
Still in 2007, a survey was spreading across LiveJournal, incentivizing users to share and discuss their own personal “headcanons” about any kind of fandom.
These discussions had gained great popularity and years later several sites and communities were eagerly discussing their own “headcanons”.
Tumblr became a popular place for sharing one’s own ideas about a fictional universe, since 2012.
- Fanlore – Headcanon