He's being selfish when he offers to take the swab for her. Lying there, she's both Holly and Nick to him until the initial rush of panic subsides and she's just Catherine.

That's scarier, somehow, and he needs to get his hands on her.

He wants to reach for her when he catches up to her outside, after the morgue. But the way Nick had shied away from hands for weeks after that case is still burned into his mind and he's afraid.

But she doesn't flinch away, and the heat of her body pressed against his is a benediction.