I think it would be DementorDelta's Devil Will Drag You Under, which showed me how you could write something so very, very wrong IRL that works so very, very well in fanfic.
You know, I think I've given more thought to that particular fic than any other in Snarry fanon, wondering at the appeal, given its subject, trying to figure out why it works. Funny you mentioned that, because from time to time I reread it, and still haven't figured it out.
I'm with the mods--more romantic non-con/dub-con! Please? Looking forward to reading your Games fic. Excellent interview!