The yelp he gives is slightly undignified, but the truth is that it feels so absolutely deliriously incredible and the sounds he's making could be so much worse. He feels like he's swimming in pleasure, dizzy with it, and it drives him to go faster, mouth working past lack of sensation because he's feeding a circle of delight, making him feel so, so good.

He slides his fingers up and down Sirius' hips, moaning happily when he feels that shiver down his spine.