Tissue of Silver isn't Underwater Light though its characterization of both Harry and Draco owe a lot to UL author Maya. However, it's easily the most entertaining Harry/Draco fic I've read in a while. The downside is its lack of explicit sex (c'mon, you know that's a huge reason we're reading this stuff); the upside is the care with which author Fearless Diva constructs her post-series world, and the characters within it who have been given a depth that, really, Rowling never managed (I'm serious).
Title: Tissue of Silver
Author: Fearless Diva
Pairing: Harry Potter/Draco Malfoy
Author Rating: R "for coarse language, brief drug use, some sexual content, and consideration of issues of sexual consent."
Author Summary: "A love story concerning possessed furniture, black silk pyjamas, courtroom drama, premonitions of doom, assassination attempts, Death Eater yoga, absinthe, bare feet and a sensible werewolf."
Length: 576K (one long chapter)
Available At: Fearless Diva's Harry Potter Fiction page (along with short pieces set in the same universe ... "Famous for Their Discord" and "Voluptas" come highly recommended) and also recorded by FayJay (for the win!) at AudioFic.
I'm not going to say a whole lot more about this, so as not to spoiler things. The basic set-up is this: in a post-series, post-war world Draco Malfoy (who served as a spy for the anti-Death Eater side) is testifying at a series of Death Eater trials. He is also flamingly gay and very Peter Wimsey in his affected non-chalance. When threats are made against his life, (ostensibly)straight tabloid sensation Harry Potter ("Super Auror") is assigned to keep him safe. Shenanigans ensue.
There are also letters to and from Draco to his godfather Severus Snape which are hilarious, and have I mentioned Remus and Sirius make cameo appearances as Harry's godfather and godfather-in-law?
And obviously the Chair of Evil. Go forth and read.