Thousands of years ago, in the time before the Great Flood, the Earth was inhabited by the Nephilim – giant beings born from the union of fallen angels and humans. These mighty creatures ruled over the world with terrible power, their half angelic spirits giving them incredible abilities and near-immortality and shape-shifting abilities giving them the ability to deceive the masses.
But the Creator looked upon the corruption of the Earth with dismay. The Nephilim had led humanity astray, teaching them forbidden knowledge and filling the world with violence. And so, the Creator decided to cleanse the Earth with a great deluge.
As the floodwaters rose, the bodies of the Nephilim were destroyed. But their half angelic spirits – the entities which we now know as demons – could not truly die. Instead, these malevolent entities were trapped on the earth forever as prisoners, and so were they’re parents, the fallen angels themselves trapped.
The waters receded and human civilization rose again, unaware of the evil wondering the lands unseen. But the demons remained, waiting for a chance to attach themselves to new hosts and once again exert their influence over the world of mortals.