How would you describe Bellatrix?
She's obviously as bonkers as they come. There's a bit of a child-like madness there. I did regress a bit as her. It sort of happened naturally. It's easy for me to go back to being a kid. You know how kids can be like savages before they get civilized? There's that sadist quality. Y'know, like boys who like to pick apart an insect for the sake of it.

In a lot of Phoenix promos, Warner has been playing up that image of Bellatrix threatening Neville Longbottom (played by Matthew Lewis) with her wand.
I did something terrible. By mistake, I poked him in his ear. I thought I could brandish the wand like a sort of Q-tip, and clean out his ear. Sort of torture it. But unfortunately he moved toward the wand as I was prodding it. And it actually perforated his eardrum. Isn't that horrific? I damaged him! He's such a nice young man, he didn't admit to me that he actually had some internal bleeding about three days later.

So you didn't even know you'd injured him at the time?
No. And it wasn't permanent. But there was pain, and blood. Well, torture happens. Sorry! Oops! I think I took my sadism a bit too literally.

Wow — that's an interesting bit of improv.
Stupid, though! Dangerous! I did feel awful when they told me.

Did you get a chance to apologize to Matthew later, once you found out what had happened?
Oh yeah. But he was deaf, so he couldn't hear me. [Laughs wildly]

You're kidding, of course.
And then ever after I was always shouting, ''ARE YOU ALL RIGHT, LUV?''