Internal fanon = the "fanon" believed by the author(s) of a given fic.
External fanon = using "fanon" based on other fics. Or, writing a fic in a series you only know from fanfic. Almost anyone who writes Akane from Ranma 1/2 as a totally irredeemable psychopath is using external fanon. Canon, she's short-tempered, insecure, and merely a bad cook. Fanon, she swings the mallet of DHOOM at the merest twitch from Ranma and her cooking is radioactive.
There may be some other "fanon" that comes into play when a manga becomes an anime: filler fanon. That is, the events that are altered from canon to fit a TV rather than manga trope. For instance, Naruto jutsus from the anime filler arcs are seldom as imaginative or iconic as the main jutsus from the manga. I presume there must be a "Freaky Friday" episode of Naruto in the filler somewhere.
''We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat
them unconscious and rifle their pockets for new vocabulary.''
-- James Nicoll
External fanon = using "fanon" based on other fics. Or, writing a fic in a series you only know from fanfic. Almost anyone who writes Akane from Ranma 1/2 as a totally irredeemable psychopath is using external fanon. Canon, she's short-tempered, insecure, and merely a bad cook. Fanon, she swings the mallet of DHOOM at the merest twitch from Ranma and her cooking is radioactive.
There may be some other "fanon" that comes into play when a manga becomes an anime: filler fanon. That is, the events that are altered from canon to fit a TV rather than manga trope. For instance, Naruto jutsus from the anime filler arcs are seldom as imaginative or iconic as the main jutsus from the manga. I presume there must be a "Freaky Friday" episode of Naruto in the filler somewhere.
''We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat
them unconscious and rifle their pockets for new vocabulary.''
-- James Nicoll