it has never, ever occurred to me to go looking for fanfic on novels I've read
I usually don't either, but did look to see whether there was fanfic based on
Wicked: The Life and Times of the Wicked Witch of the West, my latest obsession. Thing is, though, that I
know nobody will be able to even get close to Gregory Maguire's style and ability to evoke atmosphere, or at least I'd have to wade through a whole lot of garbage in order to find something of good quality, so I gave up on that idea pretty quickly.
To me, when it comes to novels, it's not just about what the writer's saying, but
how he or she is saying it. Prose, dialogue, descriptions, attention to detail and plot: it all comes together to form a whole. And that's a lot tougher to emulate than a TV show or movie, I think.