Another possibility is that it's an accidental result of a powerful magic clash between Voldemort and Harry. When their magic collides in a certain way, it causes an unexpected transformation on Harry, turning him into a girl. This would add a whole new layer of complexity to their relationship and the overall story.
One way it could be plausible is through the use of dark magic manipulation. Voldemort is a master of dark magic. He could perhaps use some form of mind - altering spell on Harry. If he managed to get Harry in a vulnerable state, like when he was feeling isolated or betrayed, the dark magic could seep in and start to change his nature. For example, if Voldemort made Harry believe that his friends at Hogwarts had turned against him, Harry's sense of justice and goodness might be warped, leading him to the dark side.
In some fanfiction, it might be related to a hidden magic within Hogwarts itself. There could be a mysterious force in the school that reacts to Harry's unique connection to the place. For example, if he uncovers a long - forgotten chamber or artifact that has some sort of transformative power. Since basilisks are associated with the Chamber of Secrets, it's possible that something in that area could be the cause.
Well, she might struggle with her new identity at first. Her relationships with Lois Lane and other friends could change completely. For instance, Lois might be initially confused about her feelings for this new female Superman. And her friends in the Justice League may have to adjust to her new appearance and the different way she now approaches problems.
Well, Finn could start to notice how differently people treat her as a girl. Some might be more protective, while others might underestimate her strength. This contrast in treatment could fuel her determination to prove herself.
Well, she might face discrimination at first. People in the hero world could have different expectations of a female hero. Midoriya, now as a girl, would have to break through these stereotypes and prove herself just as capable as she was before.
Well, when Kuroko turns into a girl, it could lead to a whole new set of adventures. For starters, she would have to deal with the physical changes. Her voice might be different, and she would have to get used to the different body mechanics. In the story, this could be a source of humor as she tries to run or jump as she did before. Also, her relationship with the coach might change. The coach could be more protective or have different expectations of her. And the story could also explore how she copes with the reactions of fans, who might be very surprised to see this new version of Kuroko.
Well, if Harry is captured by Voldemort in fanfiction, it could lead to some really dark and intense scenarios. Voldemort might torture Harry to get information about the resistance. Harry, on the other hand, could be secretly planning an escape while pretending to be broken. There could also be a rescue mission by his friends, which would be full of danger and drama.
She might find herself in a very dangerous and dark world. Maybe she'll have to use her modern knowledge to outwit Voldemort's followers. For example, if she knows some self - defense techniques from the modern world, she could use them against the Death Eaters.
In some fanfiction, this could happen through a powerful spell gone wrong. Maybe Snape was attempting a complex transfiguration spell for some secret reason, like protecting Harry from a dark magic threat in a very unorthodox way. And the result was Harry being turned into a shifter.
Perhaps there could be a love interest that is unique to his female form. Maybe someone who didn't notice Danny before as a boy, but now is attracted to him as a girl. This could add a whole new layer of drama and romance to the fanfiction, as Danny has to figure out how to handle this new relationship while still dealing with his ghost - hunting duties.