I could imagine an all-female Jekyll and Hyde situation without any mind control. It could even be a kind of realistic setting with her having some mental illness.
Innocent girl at day, slut at night.
It could start with J waking up in another man's bed, asking him what happened. He laughs and replies that she didn't drink enough alcohol to have a blackout but offers her to renew her memory while removing the duvet and pulling her head down to his naked crotch. J screams, accuses him of being a rapist, takes her clothes and runs away. (Maybe even report it to the police)
After a few days of similar incidents, she could ask a good (female) friend of watching her as she goes to sleep. The next morning she wakes up, finding her friend butt naked and tied spread-eagled to her bed. Her embarrassed friend tells her what happened, that she tied her to bed, forcing her to have sex all night long while being completely different. She also tells her that she didn't call herself J but H.
J feels pretty bad (and her jaw hurts), so the next evening, she tries to communicate with H. She ties herself with a combo lock and leaves H a note with the request to answer. The next morning she awakes in a stall of a men's public restroom, wearing a slutty skirt and feeling sore between her legs. There is some lipstick writing on the closed door, telling her to never lock herself up again, noting some souvenir pictures on her phone. With tears in her eyes, she opens her phone and looks at the selfies, showing her in front of a sink with cum oozing from her pussy and an ogling guy in the mirror in the background.
Horrified, J takes the pill after and H isn't amused as she feels horrible that night. H could film herself while getting fucked by two guys, using condoms. At the end of the clip, she tells J to make a similar vid, blackmailing her into having anal with a man of J's choice without using a condom and taking his cum in her ass or sucking him off. If she doesn't do it, H promises to repeat the threesome without condoms (every day till the end of their life).
(probably such a thing already exists ^^)