I wish I had time to think through and articulate exactly what I find so phenomenal about it, but succinctly put it's an experience. Since the Olympics just happened, let's go with a sports/performance metaphor: You know when you're watching a gymnast on floor, and you know, YOU JUST KNOW, even through the TV, that they are absolutely nailing their routine? That's this fic.
It takes place in mid-S6, just after Sam's soul has been returned and the Wall has been erected--and Sam and Dean decide (naturally) that the thing to do is hunt a wendigo in a cave. But it turns out any wendigo, if they can find it at all, is the least of their worries.
Sam has the most wonderful narrative insights here, about himself, about the soulless version of himself he never met, about Dean, about who they used to be, last time wendigo came calling, and the creeping, unsettling horror of this is just pitch-perfect. The images stick with you, runnel into your marrow, and the whole thing wraps so many different layers of estrangement and dread up in one another it's a veritable feast.
This fic goes beyond atmospheric--it makes place, surround, a live and awe-striking thing. ♥
(P.S. I also want to say that my Summergen recs have been EXTREMELY SPORADIC, with regard to my thinking "omg this is so amazing I wish everyone would read it" and then my actually writing--or more often, not writing--the post that says so. =___=;; But this round has been SO GOOD. And there are so many I need to go back and rec individually! But because this will take me a glacial age, please check out spn_summergen in its entirety! Hands down my favorite round, of all seven I've taken part in. <33333)