When we begin the game, If the player drink the good juice then quickly equip the holy hammer afterwards:

The holy hammer will make batty leave us alone so the player won't become a vampire.

If the player wants to be a vampire then he shouldn't equip the holy hammer so batty can turn him into a vampire.

Bonus:  Only if you don't become a vampire, batty becomes a boss at some point in the game.

The "not a vampire" run would be like some sort of a hard mod since it is much harder to acquire juice when you can't drink the juice of the corpses.

I like the idea of avoiding becoming a vampire. I approve of this.

you are able to skip batty i'm trying to speedrun the game. you skip him by leaving the cematary VERY quik