Regulus was straddling that line between enjoyment and discomfort. His body was reacting despite everything, because he was still twenty and hormones went a long way at his age, while he tried to get his mind to shut down. Then Remus' mouth was gone and he was left staring at his lover, trying to come up with an answer to an impossible question.
"Nothing... you did nothing wrong," he said, because he needed Remus to believe it.
He propped himself up on one elbow and smoothed Remus' lip with a finger. "You were fine. Just getting impatient, that's all." So that wasn't technically a lie, although it was easier than explaining something he didn't even understand. "Just wanted you."