There's enough uncertainty in Kieren's answer to make Sirius wonder. He's well aware that werewolves exist in this place just as they had back home, of course. He's even met one himself, a friend of Magnus's and owner of a bookshop. But this is the first time he's really considered that Kieren could be a victim to one. He'd not thought of it much before seeing as, for quite a long time, Kieren had been impervious to such things.

But now...

Now Kieren was just as human as anyone else. He could be turned, either into a werewolf or a vampire or harmed in any number of ways. Just rolled over by a bloody car.

"Do you want some tea?" he asks because if he doesn't do something right now, he's liable to break something his nerves. Kieren is undoubtedly weary and he'll likely not react well to Sirius's fretting, but it doesn't seem to be something he can control well at the moment. "I'll put a few more wards on the walls tonight," he vows then. "And I can make something for you to take with you when you're out. A protective object of some kind."