There's a pause as Sirius thinks about that for a moment. He hadn't considered charging for his services. Mostly he'd just thought that this would be an interesting situation and he'd get some fun out of it. Certainly not out of the goodness of his heart, no matter who might try to tell him otherwise.

"Not really," he says finally, "But now that you've given me the idea, I'll settle for a favour. House is just up ahead."