Hmmm, still wouldn't do it for the majority of the male population. You'll need to make the fighting occur because neither of them wants to be saddled with the pathetic excuse for a craven coward that the 'prophetic hero' turned out to be, and they're being told they have to make the prophecy happen so the world could be saved. Then, over the course of the story, it turns out the werewolf girl has magical properties in her blood that allow the vampire chick to power up and defeat the BBEG. The twist? The powers in the blood only activate when she experiences the bond of human love from the pathetic hero they're now dragging towards destiny, so the two women folk monsters must team up to win the heart of said pathetic hero despite his raging craven fear of them. Obviously there will be a sensual scene of the vampire sucking blood from the werewolf.

Boom. I just wrote the next hollywood flick. Good thing the strike is over.