His family members might also be important characters. His parents, if they are alive in the fanfic, could be the opposite of Harry when it comes to snow. They might be the ones who want to take family pictures in the snow every year, and Harry dreads those moments. Or a younger sibling who is always excited about snow and can't understand Harry's dislike.
One of the main characters could be a Protoss high templar. This character could be the one who first discovers Harry and decides to take him under his wing. Another could be a Protoss zealot, who is initially skeptical of Harry but later becomes his ally in battles.
Ron could also be a major character. He might have a hard time accepting Harry as a girl at first. But as the story progresses, he could become more understanding and protective of Harry in this new form. And there could be some really funny and awkward moments between them.
Hermione could be one of the main characters. She might be suspicious of Orochimaru's teachings and try to convince Harry that it's wrong. She would be constantly researching about Orochimaru and the type of magic he's teaching Harry to prove her point.
Dumbledore could also be an important character. He might be the one who tries to figure out what's wrong with Harry and tries to reverse this hatred. Another character could be Snape. He might see this as an opportunity to make Harry's life even more difficult or, on the other hand, might be secretly trying to help him get over this hatred.
Hermione could be one of the main characters. She might be the one who tries to find Harry and bring him back. She would use her intelligence and knowledge of magic to track him down, all while worrying about his safety.
Rainbow Dash might also be a main character. She's brave and loves adventure. She could take Fem Harry on some wild rides around Equestria and introduce her to the exciting parts of the world. They might even get into some friendly competitions.
An older, wiser mentor figure could be included. This person has seen the world and can offer Harry advice on how to grow out of his playboy phase. They could have a backstory of their own, like they were once a playboy or knew someone who was and learned from their mistakes. For example, he could be an old actor who has retired from the limelight and now wants to help the younger generation.
Hermione would most likely be one of the main characters. She's always observant and caring towards Harry. So when she notices something is off with Harry, she would do everything in her power to figure out what's wrong and help him. She might use her extensive knowledge of magic to find a solution to his emotional distress.
Hermione would surely be involved. She could be Harry's research partner, helping him find relevant medical information in books and scrolls. Her intelligence and thirst for knowledge would be very useful in exploring new areas of medical magic. Another character could be Madam Pomfrey. She could be Harry's mentor, teaching him the basics of wizarding medicine and guiding him in his new role as a medic.
Hermione would surely be there. She might be a fellow professor, teaching a subject like Transfiguration or Ancient Runes. She could be Harry's confidante and help him with academic matters at Hogwarts. Also, Ron could make an appearance, perhaps as a visiting lecturer from time to time, sharing his knowledge of wizarding chess and other aspects of wizard culture.