"Right, right." Q nods. Then he takes a deep breath and tries to explain. "Sorry, it's just that, well, the Sirius Black I knew would have charmed my chair to collapse under me, or gotten me tea in a nose-biting cup." He looks away from Sirius, fingers dancing an arpeggio on the table. "So I feel a bit like I'm waiting for the other shoe to drop." He looks up, managing a more genuine smile. "It's all very well for Heinlein and Gerrold to write about the same person from different dimensions, but it's quite another thing all together when you encounter it in reality. I had, have," he shrugs, "quite a grudge against the other you. I was quite prepared to despise this you. I'm sorry about jumping to conclusions." Q looks away again, flushing a bit.
"Um, this." He takes the top book and pushes it over to Sirius. It's Animagus Transfiguration: Unleashing Your Inner Animal. "Er," Q clears his throat, "I wanted to try it and well, it seemed like a good idea to get some information from someone who can actually do the transfiguration."