Apogee by OpalApparition - where Commander Shane Hollander and Flight Engineer Ilya Rozanov are stranded on the International Space Station and have to survive a solar storm. It's an amazing mix of hard science, detailed knowledge of the ISS, space program history, intense action/adventure, gripping drama, an incredibly repressed Shane, pining, jealous Ilya, incendiary sex in microgravity, and romance. The writing is extremely good - gripping, fluent, with great descriptive detail. It's the best complete AU in the fandom I've read so far. (50,348 words)
I'm very into everything by OpalApparition, especially
Wolfbird - a regularly updating WIP featuring professional dom Ilya and extremely uptight hockey star Shane. Although the way they meet is a BDSM club, in fact the fic's largely not about that (although there are several extremely hot scenes). It's more about the two characters, as despite his in-control dom role at the club, Ilya's actually a complex mess, an illegal overstayer with a ruined knee after a disaster very early in his NHL career, and Shane is the profoundly repressed hockey-robot star he'd be if he'd never met Ilya as a teen. It's addictive, and, as above, beautifully written. (currently 170,925 words)