That gesture of affection might have seemed small and inconsequential to some, but for Remus it meant all the world. He didn't let people in like this. He couldn't. But that didn't mean he wasn't longing for closeness. Depriving himself of it was because of his condition, not because of an empty heart. He cared deeply for his friends, and that feeling ran even deeper for Sirius.
He'd never really heard him say anything like that before. He knew Sirius had a heart of gold, and was the most loyal friend anyone could ask for (which was exactly why his betrayal concerning The Incident had hurt so much), but it was mostly due to his actions, not necessarily his words.
Slowly, he tilted his head toward the hand caressing his face and nudged the other boy's palm with his nose. Maybe it was the wolf in him, or maybe it was just Remus being affectionate. "That's what I want most for you," he murmured, and placed a hand on his friend's knee.