Lady Jean Grey, Black Queen of the Hellfire Club

In order to gain favor with Sebastian Shaw and the villainous Hellfire Club, the mutant Mastermind used his mind control powers and a device from Emma Frost to slowly corrupt X-Man Jean Grey, aka Phoenix, and convince her she was his wife. She turned on the X-Men and (briefly) became Black Queen of the Hellfire Club. Cyclops almost getting killed broke Mastermind's control and the X-Men escaped the Hellfire Club, but then...Jean lost control of the Phoenix Force and became the Dark Phoenix.

She only appears like this for maybe a dozen panels (making for a tough training), but it made an impression on a young reader. Chris Claremont, partly responsible for a generation of mind control and corruption fetishists.

Backup location: https://huggingface.co/ottopilot/LadyJeanGrey