Sirius Black: Sorry about the bite. I reckon that twinges a bit.

Ron Weasley: A bit? A bit? You almost tore my leg off!

Sirius Black: I was going for the rat. Normally, I have a very sweet disposition as a dog. In fact, more than once, James suggested that I make the change permanent. The tail I could live with. But the fleas, they’re murder.

From Harry Potter and the Prisoner of Azkaban (2004) | Produced by Warner Bros.