Okay that's kind of hot. He marks that on the list of things he didn't know about himself or about David for future reference (of course they'll be doing more of this in the future) and works his way down the length of him in slow, measured bobs. The angle's not ideal for getting more of him in his throat but it's more than enough to swallow around him and to keep adding the edge of his teeth here and there. Dangerous little surprises.