Sephiroth sees where this is going, and he closes the rest of the distance himself, rather than be passive this time.

He doesn't know why (it's the cotton candy), but David's touch hasn't put him on edge as he's used to. There's no instant repulsion. Maybe it feels... good? He doesn't realize how touch-starved he is, he chalks it up to curiosity, but maybe it's worth exploring further.

He's kissed before, but not much, and not at all recently. Accordingly, he's not very good at it.