Dunno, really. Maybe Bellatrix was so evil that she wasn't a normal human being any more? Maybe she was taking after her master and doing some nasty experiments?

Well, anyway.

One small thing I liked was when Neville woke up and there were two wizards doing the spell link thing with two Avada Kedavras. I found that better than everyone else who was like, "Oh, who gives a crap that I might die, let's cast magical blue spells that turn red when they meet AK."

Also, well, the canon sort of flew out the window when everyone started blocking Avada like they hadn't a care in the world.