This was written for vail_kagami's awesome prompt at the Sam-week comment fic meme: Castiel has become addicted to the whole soul-touching thing, and Sam's soul? That's something special he can't get enough of. That doesn't make it any more pleasant for Sam.
Warnings: SPOILERS for season 6 up till 6.18: Frontierland. Gore, violence, much creepiness, mild swearing. Also, twisted!Cas.
( Every time Castiel comes back, there's something missing. )