I've just finished a fic that I started, believe it or not, in 2006. It was an absolute nightmare to write, for some reason - I literally worked on it continuously for all that time, though it's not even long (about 1500 words). It's from Maya's POV, which was a large part of the problem, really, because we're given so very little of her in canon. I also had to pack a whole lot of psychological complexity into it, and it somehow demanded to be done in a very "compressed" format, which meant constant weeding out/distilling down, which can be very hard in its own right.
(And yes, I know it's a little mad to work on a piece of fanfiction for that long. To be fair, I wrote other things in the meantime, too.)
Anyway, it's done now, and since I'm not a native speaker, I feel I should run it past a beta. Yet all my former contacts in this fandom aren't active anymore, and I'm not sure anyone still is, really...