Batman and DC Comics-verse.
The Misfits, by Matt the Batman Fan.
A Batman/DC comic AU/divergence that takes place just a bit before the recent crisis, and manages to change everything. As the author's own very brief summary says: "It's amazing how only two people can screw everything up."
This has got to be one of the very best fics in the entire fandom- and by this point I've read a lot of them. The plot-line is engaging, pretty unique in this fandom, and actually does a few shocking things without being over-dramatic or tasteless. Even though it is an AU, it does take note of and somewhat follow current cannon- though not all of it, and not always for the same reasons. The most interesting thing about this fic, and one of the things that makes it most unique compared to a lot of fic in this fandom, is that it both focuses on a group of characters that do not get a lot of 'air time' in fandom, especially together, and that it generally does not focus on the more 'popular' characters in fandom at all. This is not a 'fix-it' fic, even though some people are saved, don't die, are brought back, or at least are more sane and happy- some of the characters who have died in cannon recently are still dead- some of the living are still angsty and crazy- but it isn't their story anyway. I can't really say who the main characters are without spoiling some of the best initial plot-points, but I will say that this is the very first fic that actually made me like Batman as a character. Go: read.