The story
He raised the boy king. Now the boy king won't let him go.
The regent used to be a tutor in the modern world, and he's the one who raised a young tyrant into a king. On his wedding night, the tyrant pins his regent down. The teacher meant to tame him, but instead he's become the one weakness of a mad king, and all that taming ends with the teacher locked in a cage. Then rebels strike, and the regent steps in front of the king and takes a poisoned arrow himself. The king howls the truth. He never wanted the throne. He wanted him.