Dean tenses at the mention of Sam, digging his teeth into his lip. He can't help it, but he can help saying anything about it. Anyway, Sam isn't the point right now. Cas is.

"You don't need to heal me, Cas. When I say having you back is the best thing I can think of, I mean it. Healing or no healing." He slides his fingers across Cas' scalp, coming through his hair.