I've read thousands of fanfics over the years in at least ten different fandoms, and Iolokus is my gold standard.

And it's funny, I can easily pick out half-a-dozen things I really don't like about it (wrt to some of the above comments, there are plenty of places where I myself can't "see" the characters as Mulder and Scully (I have had a bunch of arguments with my dearest Phileish friend about it--she thinks the characterization is perfectly "them". We both love the story but for different reasons).

I love so much that it's so balls-to-the-wall, so unafraid and that it pulls out all the stops. It borders strongly on parody, but I think it's so well written and such a tearing good story that it's hard to be offended.