Title: Overshadow Overwriting
Protagonist: Danny Fenton/Phantom
Harem Type: Somewhere between Hypnotism and Magic
Protagonist involvement: Deliberate
AU: Accident Happens when Danny's 18
Summary: While playing around with his overshadowing ability Danny discovers a new twist: while possessing someone he can access their brains and make a lasting changes to... all of it, their memories, their personality, their interests etc
Now this awakens a dark part of Danny, a part fuming over the way he was risking his neck to protect the city, when everyone hated him. With his new power he decided he would take his reward, and does so by possessing a girl he's crushing on, rewriting her mind so that she is he permanently loyal girlfriend/sex slave. Soon however another though occurs to him... why stop at just one?
Title: Dani's Obsession
Protagonist: Danny Phantom
Harem Type: Magic
Protagonist involvement: Incidental
AU: Danny is 18 during D-stabilized, Danielle either was always his age, or was transformed into his age after being stabilized
Summary: Most ghosts have obsessions, a single driving force that influences everything about them. Usually the obsession forms at the point of death, either continuing an obsession they already had or unifying all thoughts in the ghost's head as they die into a single idea to drive them forever. In the event that they are formed without an obsession, focusing on a though for long enough can cause their brain to develop an obsession with a similar snapshot method.
Dani Phantom never had an obsession, perhaps because of her clone nature, but after her second encounter with her original, Danny Phantom, she began to fixate on something: a desire to thank him for saving her, spending weeks racking her brain for ways to make Danny happy, gradually building up the mental pressure to create an obsession.
Unfortunately when the time finally came, she happened to phase into a strip club, and when her brain took a snapshot to form her Obsession her mind was split between ways to please Danny, and sex, which of course resolved into a simple concept.
Danielle's Obsession: Sexually pleasure Danny.
This instantly transformed Dani into Danny's sex slave (not that Dannny knew or wanted that) but the newly oversexualized girl developed several... damaging perspectives from the strip club unknowingly responsible for her new mentality:
1. Men liked woman with Large Breasts and a big butt; which resulted in her body reshaping itself into an exaggerated hourglass figure that'd make Maddie Fenton and Desiree look prepubescent by comparison
2. Women's clothing should be as revealing as it possibly could, which led to her outfit transforming into stripper clothing
3. Women should be caked in cosmetics
4. At all times women should emphasize their sexuality
There were others, like being totally obedient and so on that helped shape the new Dani but one thing resonated above everything else; the men who had the attention of multiple girls were happier than the ones that only had one.
This let to her developing a new power, she could create blank duplicates, which she would launch at people, with whom they would fuse, permanently transforming women into halfas that share Dani's obsession (this would include ghost women, they'd develop a human half and their obsessions were rewritten) while rewriting their body and mind to fit Dani's idea of sexy, although they wouldn't have the power to make duplicates like hers.
Immediately she set out to create more 'sister' sex slaves for Danny, before finally joining his side. Who was she targeting? Well as part of her obsession she developed a one way psychic link with Danny, allowing her to tell who he wanted. The problem? Her criteria stretched from girls he had vaguely lustful feelings about (for example celebrities, either from the real world, or crossover characters) all they way to any women he loved in any way, which yes, includes Jazz and Maddie.
As oversexed women suddenly begin showing up on Danny's doorstep can he figure out what Dani's up to and stop her before every woman that's ever garnered more than ambivalence from Danny ends up his slave?