I have to admit one of the most daunting things about fanfic for me, as an undertaking, is the reality that the readers would know more about the subject than I did. Some of the earliest fanfic I read was in print Star Trek novels and I was among those who knew classic Trek episodes line by line. (Oh where oh where has that part of my brain gone?) When I found errors in the books I was irate! How could anyone make such a glaring mistake when it was obvious in episode 23 that…blah blah blah.
If I ever attempted fanfic of my own I’d definitely head for stories “similar” to the established characters, but put them in my own world so I could be the puppetmaster. Perhaps one of the reasons I rarely deal in repeating characters is that I’d have to remember all the things that happened to them before. On that level, creating fresh is easier.