Back to the subplot with the catboy:

Schrödinger: Doc, we’re about to test your final plan. Wait until Alucard starts drawing in blood, then add mine to the mix. As part of his collective of souls, I won’t recognize myself, so I’ll cease to exist.

Which leaves him trying to divide by zero. Here goes nothing–!

Penwood: That can’t possibly work, can it?

Bertie: Do I look like the sort of chap who understands great scientific principles?