Fan fiction is what literature might look like if it were reinvented from scratch after a nuclear apocalypse by a band of brilliant pop-culture junkies trapped in a sealed bunker. They don’t do it for money. That’s not what it’s about. The writers write it and put it up online just for the satisfaction. They’re fans, but they’re not silent, couchbound consumers of media. The culture talks to them, and they talk back to the culture in its own language.
This is probably the best, non-judgmental description of fan fiction I’ve ever heard of in main stream media.