Ok, I remember borrowing this book from a friend back in 1993. I seem to recall the name being The Inept Adept, but I can't find anything related to this name except a piece from the 2000s that doesn't fit the description.
The book was the first in a series about a socially awkward/oblivious scientist from the present that develops a method of time travel using buckyballs. He travels to the middle ages (fantasy style), and falls in with a small group led by a woman. He keeps giving them small inventions from the future (he makes soap, so the female leader doesn't have to smell how bad her men smell; he grinds glasses for one of the men who can't see well) and as a result they consider him a wizard.
The only thing I can remember about the villain is that as the novel progresses, he hints that he can “hear” the book's narrator. I remember it being a cool concept.