Dancing with the Devil

AU. Castiel sells his soul, but instead of selling it to Hell, he sells it to a demon known as Dean. Castiel is allowed to live the rest of his life, but when he dies, he belongs to Dean. After (and even before) his death, Castiel finds himself falling in love with this Dean. But when he's offered salvation by an old friend, he is forced to make a choice that could ruin everything.