She's so worried that she's going to mess this up, that she'll be a disappointment to him. But she leans up at once, taking the invitation of his lips.

Her breath trembles a little between them, nervous little hitches against their lips as she tries to return the kiss, doing her best to follow his lead. With the kids her age she's been more confident, since they're all experimenting together. But with him, she knows that she's inexperienced, and some of the things he's just said about those fumbling, handsy teenagers make her afraid of earning his disdain in turn.