Fortunately for her, Klaus isn't the sort to ever relinquish control, even when he looks as if he might have. He's very aware of exactly what would happen if he bit her, or what might, at least. There's no way to know how the nanites might have affected his bite, or his blood's ability to heal her from it, so he's not going to risk causing her the agony of a wolf bite for the sake of an admittedly fantastic shag. He growls when she bites into him, making the urge to return the favour greater, but he still holds himself in check, even with his face in the crook of her neck as she drinks from his, his hips still pounding into her, as fast as they can now make it, and it's all of it more than a little savage, wild and almost animal, but so much more than that at the same time. It's them, and what they are, and what they can be together, and it is glorious.