Ron could also be a main character. He might be a bit scared or jealous of Harry's new - found ability. But in the end, he stands by Harry. Maybe there's a scene where Ron has to overcome his fear of snakes when they are in a dangerous situation that requires Harry to talk to a snake for help.
Harry Potter himself is often a main character. Since he is a Parselmouth, his connection with snakes makes it logical for him to be involved. He might be trying to understand the true nature of a mysterious pet snake he has found or been given.
Well, obviously Harry Potter himself is a main character as the title implies his role as the master of snakes. Hermione Granger is often involved too. She might be curious about Harry's new ability and help him research it, or she could be a bit wary at first given the negative connotations snakes have in the wizarding world.
Hermione is often involved. Since she's Harry's best friend, she might be the one trying to prevent his death in some fanfictions. Or she could be the one who has to carry on his legacy after he dies.
Hermione is often involved. She might help Harry understand the complex magic associated with the Elder Wand. For example, she could research in the library to find out any hidden lore about the wand.
Ron could also be there. He might be in charge of something like the Gryffindor Quidditch team or be a part - time teacher teaching the younger students about the magical history of the Weasley family's inventions. His humor and loyalty would be a great addition to the story.
Hermione Granger is often involved. She's Harry's best friend and is extremely intelligent. Her knowledge of spells and magic history can be crucial in helping Harry prove his innocence. She might research old laws or spells that can be used as evidence.
Dumbledore can also be a significant character. He might be the one who arranges for Snape to teach Harry, having some grand plan in mind. He could be observing from the sidelines, guiding Snape's actions and Harry's progress subtly.
Hermione is often involved. She would be curious about Harry's new ability and might try to research more about it in the library. She could also help Harry figure out how to use this ability to their advantage in different situations.
Another important character that is often involved is Hagrid. He might be the one who stumbles upon the forgotten twin sister in her hiding place or he could be the one to introduce her to the wizarding world properly. Then there are the Weasley family members. They could play different roles, like Ginny might become the twin sister's best friend or Fred and George could include her in their pranks and adventures, adding some light - heartedness to the story.
Another character could be Draco Malfoy. There could be fanfiction where Draco, having been on the wrong side for a long time, now has a change of heart and wants vengeance against his own family or the Death Eaters who used him. He might use his knowledge of the Dark Arts that he learned from his family, but now turn it against them in a bid for redemption through vengeance.