Adam Hasting's father runs one of the biggest genetics facilities on the planet. The work the lab does is extremely controversial, and there are plenty of people who desire to see them shut down. The threats don't stop at the lab either. A number of groups have made plausable threats against everyone associated with the company, including Adam, who wants no part in the family business. Adam is a senior in college and aspiring to be an artist.
No matter how much Adam distances himself from the family business, the threats are getting closer. Campus security arrests several people intent on harming Adam, and that is when Adam's father decides Adam needs a bodyguard. The genetics company has been working on artificial people, people literally born to complete a certain task. They had no superhuman abilities, but they are encoded with knowledge and skills to make them excel at their work. Eventually, some will be sold as bodyguards who are utterly loyal, while others will be used for things like physical pleasure.
Despite his protests, Adam is given the first of these companions, a young woman conditioned with exceptional threat assessment and combat abilities. As a companion mean for Adam, her likes and interests are based off a brain scan of Adam that was done years ago. All companions are designed for pleasure to at least some extent, so she is conditioned to find Adam extremely desirable, and to have the same tastes that he does. That conditioning explains why she secretly craves to be tied up, especially when she is in Adam's presence.
I would like to see this develop from a relationship where Adam might initially resent her presence and try to ditch her during the evening, and eventually become something where they come to care for one another. The idea that Adam might get hurt is unacceptable to her conditioning, but becomes terrifying to her personally. I would also like to see her develop feelings that make her want to be more than just a companion to Adam. She loves him, and wants him to feel the same.