There's plenty he could say in response to her confession, but it's pure, simple instinct that finds Bucky ducking his head to press a lingering kiss to Natasha's mouth instead, one full of intent he won't act on despite wanting to, the fantasies of his younger self fresh in his mind from their closeness. When he breaks away a few seconds later, he doesn't go far at all, resting his forehead against hers, and drawing in a deep breath through his nose. He doesn't tell her what she already knows, that he was just as dangerous even with the easy smile and go get 'em attitude. Rather, he leans in again, mouth brushing against her skin as he murmurs, "Missed you, too."