One of the best Cas/Sam fics I've ever read. It's terribly bleak, especially considering how it will end for all of them. I liked how Cas wasn't some innocent, clurless virgin in this, but someone who was hardened by the world and knew what he wanted. Castiel's fading grace added to the hopelessness of this, and the subtle way in which you protrayed Sam's loneliness here, through Dean's refusal to take him back and his memories of Ruby and Jess, and even through the way he does but doesn't really connect with Cas is heartbreaking. You can almost see Lucifer waiting right behind the corner.