Jack is sick. This never happens, really, usually it's just little colds, a sore throat, something small. But this time he's really sick, weakened and fevered. It's probably all the traveling, Claire tells him, kissing his forehead and tucking him in. Jack would be secretly basking in the touch, the motherly concern, but he can't focus on her very well, and her voice is coming from far away. He can barely even feel the kiss.
When Jack wakes up hours later, he's given cold medicine that revives him a little. They can tell it helps because he begins to complain that his hair is dirty. Avery takes pity on him, frustrated at being seen like this. Jack is defenseless like this, unpolished and weak, and it's pushed him so close to tears that Avery runs a bath.
Jack curls up in the hot water like a child, letting the bubbles stick to him. Avery was going to leave, but he can't let Jack keep sitting there until the water goes cold--or worse--until Jack falls asleep again.
He stays.