Since 5th HGW Gilgameshu swam in the black grail poop, and thus got a flesh and blood body, then doesn't that mean a Hellsing type vampire who drinks his blood as he dies would then be able to enslave his soul since they're actually just blood drinking shadow demons with a kinda shadowy soul space that houses the souls they ate? I can't think of any other way to get her a pocket treasury that shoots out