Etrigan doesn't bother to warn him of the vampire's approach, so Jason starts fractionally at being addressed. He turns, though he knows what he'll see-- and offers the bleach-blond fellow a nod as minute as his jerk had been, an acknowledgment of the presence of another intelligent creature and little more.

"I suppose that they are." What's the line-- mad dogs and Englishmen...

Claire had quoted that one at him, more than once. Never mind she'd been far likelier than him to go out in the noon-day sun of various tropical locales.

He crouches, a hand firmly on the rail, to find another rock.

"You don't need oxygen, do you," he says, absently, as he finds a suitable one and straightens back up.