So I have this idea for an NPC Prince that was cursed as a child that he shares his soul with a Balor Demon. Think the loosely based on enchantress from Suicide squad. So when in child prince form he is a good character but he can switch roles with the balor by granting permission, swiift actions transform/role swap. When this happens the Balor is loose but has the child in his head. This isn’t a possession as each half has control over there actions and must grant permission to change.
The balor uses the child as a safety blanket as he cannot be excorised so what goof character would murder a child, where as the child uses the balor in situations where he believes he is doing good but of course the wiser demon easily manipulates.
It would be two stat blocks. One for a young human aristocrat amd the other the standard Balor.
My worry is with the party dealing with this as the CR can fluctuate from a CR 5 to a CR 20 in a swift action. What is the best way to manage this?
I definitely plan a corruption angle only I do want the balor to be a full balor vs. a weaker essence version.
My idea is this demon is planning on converting a full mini kingdom on a political/religious view wise. Only not sure if I want the Balor to be an agent of an already Demon Lord ascended to godhood or he uses this opportunity to ascend himself into a new Demon Lord.
Maybe he disguises himself as a Protector of the child and is able to justify through bluff why his actions are ”for the greater good”