Capturing Regulus' hand, he pressed a kiss into the palm. "Predator's instincts," he said quietly. "I can tell when someone's uncomfortable, wary. The tension in your muscles is different, the way you move. It's not the same."
Something had happened, something to change the way the other man was responding, or not. Given the circumstances, it was difficult to see how it could have been anything other than something Remus had done, consciously or unconsciously. Supporting his weight on one hand, he leaned forward to press a soft kiss to Regulus' lips.
"Something's wrong," he murmured. "And if it isn't something I did, then it's something I didn't do because there's no one else here who could have done something."