Intimacy of Man by samdonne, Sheppard and a history of sex in five sections. It's funny and powerful and interesting, and I have things I've vaguely wanted to say about how they hook together, but I mostly got hit slightly harder than sideways by the last section that was completely unexpected, and also, apparently, the people of the forest moon of Endor are fanfic writers.
You really, really, really need to read this right now. Sheppard/m, Sheppard/f, Sheppard/m/f, Sheppard/Atlantis and the last is unclassifiable and deeply, deeply hilarious.
No, really. This story, right now. I have no words for how deeply I feel we all connect with the wonderful people of Endor. And the Sheppard/Atlantis is startlingly raw and painful--I expected it, but it was still a surprise.