Sam had Castiel pinned down under his weight. Both were shed of all clothing and Sam was riding Castiel slowly, sheathing Cas' cock deeper inside of his body with each rock of his hips. Nothing about this was rushed. They kissed slow, hands explored each others bodies in slow strokes and gentle squeezes. Only when Cas hit that sweet bundle of nerves inside Sam's body, did the pace speed up. Castiel had a love for knives as much as Sam did so it was no surprise for him when Sam had sliced Castiel's skin a little. The metal on his skin and the view of his lover coming undone above him was enough to send Cas into a blissful state. Sam's lips attached to the wound on Castiel's collarbone. He sucked and swallowed down every last drop of the precious blood he could get.
He would need several more nights like this before the transfer from Demon blood to Angel blood would take affect and if Castiel was willing to help him in this way, who was he to complain?