He didn't really know what it was, but he could sense the tension, the readiness for fight in the older man and responded to it in kind, remaining tensed and aware, a mouse around a mousetrap. "No Sir." he said, noticing that Mr Lupin hadn't locked up after all and seemed to be waiting for his decision - he wouldn't leave the man hanging around for him even if he had needed something urgently. "I was considering browsing but I realise I don't need to after all. I don't wish to waste your time."