Sane-Person
Two long rivals have been at each other's throats for many years, only to be sealed away in containers with people, whom of which they used as hosts. The false goddess of light was contained in an Egyptian sarcophagus and was buried deep within the dessert, hidden in an undiscovered tomb. The beast of darkness had their host killed and their dark heart torn out and wrapped in blessed chains, the heart being put in a dark marble container, that was transported to the ocean and thrown where the Earth's deepest trench was.
Before their capture and imprisonment, the highest of priests had lad a powerful curse on each of them. Both deities had a curse of mortality, leaving them vulnerable to die. If their current host were to die, they would so as well. Even if they changes hosts, this holy curse would never disappear, unless they found what the priests call, "The Unfortunate One".
This specific individual would appear long after the priests have died and this person could remove their curse, if they made him their host, either willingly, or by force. However, the priests have given this person immense protection, holy barriers, higher immunity to infections, and they are hidden from the deities visions. They can't sense his presence, nor his essence from afar, only if they themselves were close.
As time goes by, humanity would make a tragic mistake by exploring the areas that had these two trapped. Their long old war will begin once again, but this time, one to remove their curse.