Fanfics can take many forms. Most are usually short stories written about the characters of the IEE universe. This is a way for fans to feel that they are part of the world which they have followed for so long. Fan stories are usually shared with other fans via magazines and the internet.
Many sites now exist merely for fan fiction.
Of course, not all fan fiction is in the form of a written story. Similar to an RPG, each person takes the view of one or more of the characters, and writes the story from the point of view of that person. These stories involve much effort on the parts of all involved, but fans usually find it rewarding to read such works. Other fanfics leave the realm of the written entirely. Other films, or screenplays written by fans, also qualify.