The Forbidden Fruit is an item that can be found scattered around Hell of every chapter.
The Forbidden Fruit is an apple that contains power within it, though it is dangerous to the Damned Souls to eat, it is useful to Nimrod, since he is a half breed and can use the apples to further improve his skills.
The Forbidden Fruit is an apple with human like skin and has a vagina like opening on it. No one knows where it came from or how it came into existence. But is assumed as an edible source of food for something inhuman.