My Demon is a dark, supernatural romance. The story contains difficult themes including graphic violence, explicit intimacy, power-imbalanced dynamics, supernatural horror, strong language, and recurring themes of trauma and isolation.

The narrative follows Claire, a woman who has been cursed to live forever but be forgotten by everyone she meets. Her contributions and even her physical presence dissolve from the memories of others almost instantly. Claire has lived for over two centuries, and her curse has forced her to live a solitary and invisible existence, constantly moving and reinventing herself to avoid suspicion. She is exceptionally competent and organized, having honed her skills over centuries, but her work is always credited to others.

Her meticulously constructed life is thrown into disarray with the return of Malcolm Thorne, the CEO of the company where she works. Malcolm, who is secretly a demon named Malleus, is immune to her curse and remembers her completely. He is intrigued by Claire's unusual emotional signature and her immunity to his own carefully cultivated atmosphere of corporate manipulation.

Their relationship develops from a professional curiosity into a dangerous and compelling romance. Malleus, a "wrath demon" who feeds on competitive emotions, finds Claire's complex, layered emotional state and her centuries of experience fascinating. Claire, in turn, is drawn to Malleus because he is the only person who has ever truly seen and remembered her.