[First time for everything, Kate. He does an ehhh one-shouldered shrug as he works, to indicate as much. The cloud seems quite content to grow on its own now, and Sirius drops his arm for a moment, surveying his handiwork with a slightly critical eye.]

I can do either, really. Transfiguration is easier than anything else, here. It's not really that it's got limits, it's just that there's loads of ways to get to do what you want to do, you've just got to work out how to get there. With some small exceptions.

[Satisfied with the cloud's progress, he gives it a little nod. Right.]

Now, it's easier if we get a seasonable cold going in here. Shall I conjure up some mittens for you, or will you manage without?