Why is it controlled?
A person chooses to believe what the controller says. For example, if the controller says to a person "you are fat, I am the only one who does not mind you", the person believes it, becomes suspicious of himself or herself, and depends on the controlled person, believing what the controller says.
Reminds me of a clip from Black Mirror called Bandersnatch: a programmer. As a child, he was given a novel in a similar vein to the Choose Your Own Adventure genre. in 1984, he was inspired to develop Bandersnatch into a video game that allows people to make choices.
The film is related to this project: the controlled person chooses to believe what the controller says and becomes dependent on him, and in the end the controller hurts the controlled person as much as he can, and the controlled person cannot leave him. It is all about the controller's own choice.
