In the Rough (part 1 & part 2) by sangpassionne, a human AU Western.
Some people say that human AUs in the Jossverse invalidate the characterizations and can't be done, but I thumb my nose at them (and then do a little monkey dance so they won't hold a grudge). This was just neat, and hot, and though I'm never a great expert on historical fiction, this felt very solidly grounded in details to me. And it makes me happy, despite its angsty and often dark nature, because at the heart of it, it has some of the emotional dynamics that I like when I do like S/A.
Yay! So much great fiction this past week. Again, yay.