“Sirius thinks of that fable of the scorpion and the frog. The one where, to cross the river, the scorpion rides on the frog’s back. Halfway over, the scorpion stings the frog, despite the fact that it’s going to drown as well, simply because that is its nature. Sirius thinks about it, and he can’t figure out, between him and Regulus, who’s the scorpion and who’s the frog.”
