Remus' breath faltered, temporarily distracted with how good those nails felt on his skin. And when the breathing was back to normal, it was riddled with small moans, the corners of his mouth twitching into a grin every few seconds. At this point, he didn't even need to shag, but something had to happen, whatever it was.
Since his motor skills were barely functioning already, Remus didn't go down too gracefully; thankfully, there was an entire body to catch him, though he actually braced himself on an arm that fell next to Sirius' head. This was definitely much better. It was easy for Remus to position himself on top of Sirius, straddling his hips and pushing against the ground with his knees to cause such a stronger friction between them. He moaned, even louder than before, and let his head fall against Sirius' chest. It was hard to concentrate since he wanted to suck, kiss, bite, everything that he could at the same time.