What Remains by
walkawayslowly, Sam/Dean.
The [author's] back-of-the-book-summary: In Jefferson, Texas a man ends a generations-old curse and saves all the town's children, but completely loses his memory in the process. When it's discovered that he's a wanted criminal, the town comes together to conceal him out of gratitude for what he's done for them, giving him an apartment, a job and a whole new life. It takes seven months for Sam to find Dean, and when he finally does, he has to adapt to being around a man who has no idea that he used to be Sam's brother.
Yeah, I haven't even finished reading this yet, but I already love it. It's told, at least so far, from the points of view of Sam and a deputy in Jefferson who is the one who finds Dean, and then becomes his friend.
excerpts:
But sitting here now, watching Dean move in this space, he finds he can't remember if Dean had ever arched his eyebrow like that before, if the questioning tilt to his head was the same angle it'd always been. Dean locks his fingers together, rests them against the pie plate. Sam feels like his memory is the one that's lost. So many things he'd taken for granted, hadn't even thought to memorize. He watches them now, memorizes them now, tries not to tell himself it's already too late.
--
Watching Sam watch Dean, track his movements, the shape of Dean's hands as he gestured, mimicking a particularly amazing tackle they'd seen Monday night. It made him uncomfortable in ways he can't really describe; it made him want to go home and hug his mother.
ETA - yeah, so, finished it, and still awesome. just in case anyone was going to lose sleep about that.