Castiel follows immediately. While delaying the inevitable would have been tempting, he is really not that interested in choking himself. That would take all of this into a completely different direction, one they both want to avoid. So he just stands up with Sam, swallows heavily.

Castiel is tense in anticipation of things to come. It's not the good sort of the tense, the aroused sort. This isn#t about pleasure and pain - it's almost exclusively about just one of those.