I can't tell you exactly what it is about reading/writing fanfiction that makes me love it. True, you probably have to read through 99-999 really bad ones to find the good ones, but once you find it....once you find that story/poem/piece of art that fits perfectly into that universe, or wonderfully challenges that universe, or just tells you about that exact things you've been wanting to hear....once you find it - you're hooked! Classics: Fran's "Resolution", Ivy Blossom's "Origins"
(And of course, there's the smut!)
In case anyone is wondering, I'm almost 28, so I'm old enough for whatever LJ has to offer! (RL on the other hand...)