Well, Hermione is obviously a main character since it's about her getting even. Harry and Ron might also be involved as her friends, either helping her or being caught in the middle of her revenge plot.
There could be antagonists as well, like Draco Malfoy or other Slytherins who have often been at odds with Hermione. They might be the targets of her getting even, so they play an important role in the story too.
There could also be some new characters. Maybe a wizard or witch who works in a wizarding fashion store where Hermione gets her new clothes. This character could give her advice on what styles would suit her best and become a sort of friend during her makeover process.
Harry and Ron would most likely be main characters. They are Hermione's closest friends, so they would be involved in her life change. They might be the ones to give her advice or react to her new appearance.
Draco Malfoy would be a likely character. Since they are in the same house now, they would have more opportunities to interact. Their relationship could start off as hostile as always, but then gradually change as Hermione shows different aspects of herself in Slytherin.
Ron could be a main character. He might be the first one to notice Hermione's new haircut. He could have a really strong reaction, like blushing because he suddenly finds her even more attractive with the new look. And their relationship could develop further because of this change in her appearance.
Obviously, Harry and Ron would be highly involved. They are Hermione's closest friends. Harry would likely be the one leading the effort to find a solution, given his heroic nature. Ron, on the other hand, would probably be more involved in the day - to - day care of baby Hermione, with his big, caring heart.
Harry Potter could be involved. He might be caught in the middle of Hermione's revenge plan on Ron. He could try to be the peacemaker, but his attempts might backfire, leading to more chaos between the two. For example, he might accidentally reveal Hermione's plans to Ron, making Hermione even more determined to succeed with her revenge.
Depending on the plot of the 'harry gets even fanfic', some other characters from the Harry Potter universe might make an appearance. For instance, Professor Dumbledore, even though he's passed away in the original series. His wisdom might be a guiding force for Harry, either through memories or some kind of magical connection. Or characters like Luna Lovegood could also be involved, perhaps providing some unique perspective on Harry's need for revenge.
Perhaps in the fanfiction, Hermione gets even with those who underestimated her. She could expose their wrongdoings or secrets, using her skills in research and deduction. For example, if someone tried to take credit for her work, she'd find a way to prove it was hers and make them look foolish in the process.
Well, Harry and Ron would most likely be main characters. They are Hermione's closest friends in the Harry Potter universe, and in this fanfiction, they would probably play important roles in supporting Hermione through her maledictus situation. Maybe Harry would use his courage and Gryffindor spirit to stand by her side no matter what, and Ron would provide some comic relief while also being a loyal friend.
Another character could be a new teacher or a visiting wizard. This person might recognize Hermione's potential even more than the others and offer to mentor her. They could introduce her to new areas of magic and help her develop her skills further.