For as long as she can remember, your character has wanted to be a superhero. She has heard rumors of a "power broker" a powerful man with the ability to give others powers. She trades in her life savings to pay to visit the man, hoping against hope that the stories are true. The man places a mark, two lengths of a chain, on her wrist, and when she leaves, she has power! She can fly, is invulnerable, and can lift a truck over her head.
My character, the power broker, lets her make a name for herself for a few weeks before making his move. His mark on her wrist gives her power, but it also makes his wish her command. He can make her do things, but also make her crave them. He can force her to speak only the truth, or make her feel fear, desire, or sexual pleasure with a word. His goal is to make her his enforcer and sexual plaything. He could use his power over her to make her do this, but he wants her to be willing. Terms can be discussed, but I want her to have some unpleasant experiences. For example, he might arrange for her powers to fail while she is fighting one of the supervillians he created, so she could be used by the criminal and his men.