Castiel actually laughs a little, dwindling down to chuckling as Dean fades out. He sits for a moment, happy to have had some time to chat up his best friend and more inclined to look for a way to get him back, now.

After a few minutes, Castiel gains some of his strength back and starts to clean up the little ritual. Selfish, to keep it all to himself, but with more people there would have been less time to talk and likely more stress on him.