Some time ago, I happened upon a story that kind of intrigued me. However, some of the details are a bit fuzzy as I might have been high when I read it. But I think it may have been part of a series. And definitely of an erotic horror genre. I specifically recall it being told by the woman’s POV. She was a professor of, I think, archeology. Maybe a grad student. She was seduced by either a male colleague or a student. Much of the sex scene was on a table. The dialogue was mostly in her thoughts as she describes the scene. He goes into a trance like state and begins fucking her harder and harder as his cock begins growing more and more inside her. And he has this superhuman strength. She begins to believe he will fuck her to death. After he finishes inside her and withdraws, a symbol appears glowing on his chest. Something cultic or satanic.
I’m under the impression there is more to this story. I get the feeling she’s impregnated with his demon spawn. But I never could find the story again.