The situation is taking advantage of them. They're both just trying to hold on to anything that will let them survive this.

If their staggering size difference was apparent during the fight, it is absolutely glaringly obvious now. He completely engulfs her when he pulled her close. It's actually kind of nice. Not that she would admit to that, and she won't have to. She won't have to admit to anything as long as she keeps kissing him.

So when he bites her lip, she doesn't rethink the wisdom of this, or try and decide if he's reading more into it than she intends. She doesn't consider stopping so that they don't reach a point they can't come back from. She doesn't try desperately to brainstorm any other tactic that will keep them from talking. She just groans, a low and throaty sound, and bites him right back. Her fingernails sink a little deeper into the skin of his neck, her teeth into his lip, and it feels far better than she thought it would.