Ok, the lead character is a female who is a strong magician/sorceress/mage and power wise, she is the strongest of all the magic wielders in her country. Her country has a bias against female magic users. She is hired on to protect a rich female. In this story, magic wielders can summon demons and bind them to do their bidding. One particular demon becomes fascinated by the lead character and assumes human form in order to seduce her. His aim is to bind her to him so that he may use her power as well as his own. Throughout the book, the lead character resists him and every night performs spells to put protections around the rich woman. The rich woman hired the lead character because she has an admirer who became infatuated and began stalking her. In the story, a sickness starts spreading across the area where the lead character lives and no one knows the cause. Later in the book it's revealed that the demon who took human form is causing the sickness. The lead character has to fight the demon in order to protect herself and her rich boss.