Maybe Batman can open his goddamn mouth and warn her something is up? If she's already a vampire, deal with it. If she isn't, at the very least, she could stay on guard.
EDIT:
I'm going to be honest...since this series is setting itself up as yet another "powerless billionaires vs. corrupted gods" story, I'm just going to be extra & needlessly critical of everything Batman does.
As far as I'm concerned, every hero that turns into a vampire and/or dies--everything that goes wrong in this comic--is Bruce's fault. The ass-hat.