I have a suggestion for you. Write an isekai about the Hollow Knight, where the main character inhabits the body of the knight. Since a full soul enters the hollow body, he gains emotions, a voice, and a gender. And the Pale King, for show, takes him as the prince of his kingdom and uses him for his political purposes, such as an arranged marriage.
The protagonist is clearly dissatisfied with his father's attitude and some of his dishonest actions to achieve his goals. Therefore, he begins to rebel and question the Pale King's plan, and the king decides to cunningly throw him into the abyss of void.
