Long ago Pandora’s box was created to bind the Lords of the Underworld. The lords were the most powerful demons. They had millions of minions each and were causing chaos and destruction wherever they went. It took many supernatural forces to trap the Lords. Unfortunately the box was lost in time. It eventually fell into the hands of a human who released the Lords. Unfortunately the Lords no longer had physical forms making them weak. Not wanting to be recaptured they sought out bodies. They seek out human strong enough to host them. 

Now those demons have found homes in some special humans. These humans will wake up one day to discover that they are not alone inside their head. One of the Lords of the taken up residence within their mind. Some will accept their demon. Others will struggle their demon. Most of them are decent people struggling to maintain who they  before are despite the demon that now shares their body and mind. Can they find a balance so that they aren't destroyed when faced with enemies who are trying to destroy them? Can stranger who affect one another find ways to work together so that they survive the next battle?