Talk:Vampire/@comment-84.46.255.30-20130106111753/@comment-5159779-20130119134832

If you had read the book properly, Nahuel states that it is dues to random chance. It is also possible for a vampire to turn a hybrid into a pure vampire, as human blood runs in their veins, so if the bloodstream was interfered with venom, the venom would go to the heart and make the hybrid into a pure vampire.