Sirius didn't try to control Remus' hips. He wanted Remus to enjoy himself, totally and completely, and so he let him writhe beneath him, maintaining a steady easy pace, flicking his tongue over the tip of his cock every once in a while. Curling his fingers into Remus' hip at Remus' words, Sirius just groaned in response and sped up his movements, driving Remus to the brink and when he did cum he didn't pull back. He hollowed out his mouth and took all of it in, waiting until he was sure Remus was done before pulling back and swallowing greedily.