Fanon

Fanon and fan fiction are terms used to refer to "fan canon" and unofficial fiction written by fans. Harry Potter fan fiction is a way for fans of the series to explore themes and ideas that are not explored via the books by J.K. Rowling. However, in discussing the novels and films, care must be taken not to mistake fanon, and material within fan fiction, with official canon.

Individual fanon
Fanon can take the form of personal beliefs held by individuals, such as hypothesising on characters' eventual spouses and children. Examples of this are that Rubeus Hagrid married Olympe Maxime or that Argus Filch married Irma Pince. There is no basis for either of these statements in canon, and is most likely "wish-fulfillment" on the part of the fans who wish to see their favourite characters happy.

Another example of this form of canon is the identity of James Potter's parents. Some maintain that they are Charlus Potter and Dorea Black, who appear on the Black family tree, and had one son. While it seems to fit James' backstory as an only child, J. K. Rowling has never stated this to be the case.

Alternately, fanon can also be employed to explain discrepancies between the Harry Potter films, such as rationales for the change of Albus Dumbledore's appearance between the films of Harry Potter and the Chamber of Secrets and Harry Potter and the Prisoner of Azkaban, necessitated by the death of actor Richard Harris and his replacement by Michael Gambon. For example, that Dumbledore cast a rejuvenation spell upon himself. J.K. Rowling does not address the issue in her later novels, and the films make no reference, either.

Over time, elements of fanon can become ingrained into the popular milieu of an entertainment franchise. The Star Trek franchise is well-known for the development of fanon information, which has resulted in unfounded criticism being levelled against a Star Trek series or film accused of violating "facts" not actually in evidence on screen; at the opposite end of the spectrum, however, the character Nyota Uhura was officially given a first name after more than 40 years in the 2009 Star Trek film, and the name originated as fanon. Fanon is also a major aspect of the fan communities for franchises such as Doctor Who and Star Wars.

Fan fiction
Fan fiction is stories written by fans, either to continue the adventures of the main characters, or change the outcome of the canonical storyline to one they favour. Examples of this are the many stories that disregard the canonical pairing of Harry Potter and Ginny Weasley, in favour of Harry and Hermione Granger. A popular sub-genre is slash fiction, where two same sex characters are romantically paired - Severus/Harry, Harry/Draco, Ron/Draco, Remus/Sirius, Remus/Sirius/Harry, and Seamus/Ron are only some of the many 'couples'.

Other fan fiction includes the creation of a new character, and their adventures within the Harry Potter universe. These characters often take the form of what is known in fan fiction circles as a "Mary Sue", which denotes characters created based upon the authors themselves. Mary Sues (which, label notwithstanding, can be male or female) often interact with the main characters of the series and play a central role in key events. Romantic entanglements with a particularly beloved (to the author) character often occur.

Fan fiction, like all fiction, ranges in quality from the poor to the excellent. Many Harry Potter fan websites maintain their own fan fiction section for fans to post their stories. And while some elements of fandom look down upon fan fiction (particularly stories that fall within the tropes described above), many professional fiction writers began their careers writing fan fiction, and in the case of Star Trek and Doctor Who there are cases writers who began as composers of "fanfic" for these franchises going on to write official, canonical episodes later in their careers.

Fanon on the Harry Potter Wiki
Fan fiction is permitted on user pages, as long as it is not the main contribution of a user to this wiki. Fan fiction becomes fanon when the creators attempt to integrate their characters or versions of events into the official canon by adding it to existing articles or creating one relating to the character.

This type of fanon is considered vandalism on the Harry Potter Wiki, and may be grounds for permanent bans for persistent offenders.