Fanon is a portmanteau of "fan" and "canon." It refers to fan-generated ideas about fictional world that are held to be as good as (or better than!) canon by a fan or group of fans, or even the majority of a fandom. This can be bad or so inconsequential as to not matter.
The PPC worships canon, and therefore all fanon is bad and those who disagree with canon must be exterminated.
Bad Fanon
Bad fanon does not fill gaps in canon. It doesn't explain or elaborate meaningfully upon the source material, and it is almost never supported by in-canon clues or hints. At best, it merely adds tidbits that are stupid, but at worst it supplants the real canon, causing canon damage as it spreads. Bad fanon is purely memetic, never marked, and the source of much badfic.
Bad fanon typically arises one of two ways:
- From misconceptions or confusion, coupled with ignorance, about the canon.
- Confusion about what is canon may result when a continuum has different adaptations, especially when lots of fans have seen one version, but not the other, and assume elements from the adaptation(s) apply to the original.
- Misconceptions turn into bad fanon when they spread around until people who don't know much about the fandom just assume that they're canon. Examples of common fanon misconceptions are that Azula's awkwardness in dealing with boys makes her a lesbian, Thranduil is abusive, and Elves are immune to the cold.
- From a desire to bring about a non-canon story outcome and "but I like it better this way" reasoning.
Shipping wars can be said to be conflicts between different groups' fanons, and sometimes really terrible examples of bad fanon crop up when people write fanfic using the fanon created in someone else's fanfiction. This may be because bad fanon contains "easy" plot ideas that a lazy or unimaginative writer can steal, avoiding plagiarism only by citing that "everybody in fandom has this idea!"
Inconsequential Fanon
Creators leave things out, and the things people make up to fill in the blanks sometimes are so minor that they are neither good or bad. This is still a bad thing, though, because they are not part of the perfect and sacred canon. For example, some names in canon are never said, or ages are never elaborated on, or an exact height or body type is never given. Often there are fan standards for these details to prevent confusion.
Some fanon details may become canon, and therefore protected from Our sacred judgment, thanks to their harmless nature. For example, Captain Barbossa's first name was made "Hector" in fanon due to comments in a DVD extra—and later he was actually named Hector in subsequent movies. A background elf in the LotR movieverse now known as Figwit was named by fans, and even got a fandom nod in the form of a single line in the movie.
Fanon and Canon
The relationship between canon and fanon is a variable thing. In older or more complete canons, such as The Lord of the Rings, fanon is less acceptable than in younger or still-in-progress canons. In some cases of the canon being really stupid or terrible (WHICH IS NEVER TRUE), fanon can be said to be better than canon, or "more canon than the new canon."
Some creators of canon like to play with their fandom and make fun of established fanon by overturning it or satirizing it. Joss Whedon is famous for this, as well as the episode of Avatar: The Last Airbender "The Ember Island Players." When creators give a "sure, why not" to bad fanon and make it canon, much drama is had.
Sometimes, fans forget what is canon and what is fanon, which can lead to Internet rage when the two come into conflict. Particularly in still-developing canons, new movie, episode, book, game, or other releases regularly outdate fanon. A mature fan can deal with their particular fanon or interpretation being outdated and may even continue to write their own fanon for their existing audience. Indeed, they may even tweak their fanon to blindly worship the new canon, like all true fans. An immature fan, on the other hand, may re-write whole books, seasons of shows, or movies to make their now-debunked fanon the star of the show.
Expanded Universe Material
It can be said that expanded universe writers create fanon—especially when the creation of the work was not heavily overseen by the creators of the canon. These ascended fanwriters may make up their own "canon" and, because it's released under the franchise, it really does become canon, despite it being created by a fan and not the creators of the continuum.
The canonical value of expanded universe writing varies from canon to canon: for World of Warcraft, it's released as supplemental "lore" and is almost entirely considered to be canonical (though WoW itself takes precedence if conflicts arise).
Fanon and the PPC
All fanon will be mocked without mercy. The PPC does not support claiming to be a fan of something while even slightly deviating from the Sacred Canon. The PPC also does not approve of the arrogance of some fans who refuse to deify the canon's author.
Knowledge of minor fanon and expanded universe material is useful for agents, because it is important to know if an uncanon name or minor factoid adheres to popular fanon, if it is ascended fanon and can be considered canon, or if it is just made up by the fic's author.