Can't really rec anything in particular, because I haven't read H/D so much. Only bits there and here, nothing spectacular yet :D But still, I'd like to mention this site (http://notquiteroyal.net/switchknife/hd.htm) where I've found most of the good fics I've read :)

I'm way too choosy for my own good; I demand perfect and nothing less ;) That's one of the reasons why I've read so few fics with this pairing even that I started more than a year ago. I hope you fins something good to read!