That's actually a very good question, especially in the context of this post, since I think what I probably like about fanfic comes out of community norms and prevalent writing styles. On the other hand, though I am not myself a writer, I always used to imagine myself into different universes (Star Trek, Star Wars, etc.) and I imagine that's the genesis of a lot of fanfic, especially for people who don't have ready access to a fandom community, so those stories must count as fanfic, I think.

Thanks for commenting! While you are here, I have to say that The Wounded Sky is still my favorite ST novel of all time, and I also really loved the Rihannsu stories; I'm a huge fan of the Young Wizards' series; and I'm pretty sure The Door into Shadow had a pretty profound impact on my religious worldview, back in college, in addition to giving me an addiction to fantasy novels with kickass heroines.