It's rare that either of them ever has to use their safe word to end a scene, and this marks the first time punishment has failed. It's Castiel's fault, he knows that - he pushed too hard, pushed for too much, and failed to take what he himself forced Sam to do. He feels more rotten than before, and hangs his head in silent shame as Sam helps him to the ground to undo his shackles.

Castiel feels like a nerve flayed raw and open, unable to to fully disentangle himself from the scene, his sins, his guilt. He needs something, but can't voice what it is, can't ask for it, can't possible communicate it to Sam, because he doesn't know what it is that he needs. For now, he simply worries that he broke what they share.