Draco might tell him that story, though he might then also need to be intoxicated or otherwise potioned in order to do so with complete honesty. But Billy could always just ask him some time.

"It certainly doesn't sound like you're complaining... " As Draco works his fingertips searchingly deeper his current impatience is only very briefly sated by the temptingly eager squirming of Billy's hips. But since he is so decidedly eager himself, he thrusts in a bit harder now in time with a tongue-laden kiss to Billy's other cheek. Which rather quickly just becomes another bite.

And possibly one more bite, a little harder.