The two main characters are Hermione and Snape. Hermione, with her quick mind and determination, is set to take on Snape. But we can't forget about the potential influence of other Hogwarts characters. Dumbledore, for instance, might play a role in the background. Maybe Hermione goes to him after her outburst at Snape, seeking his guidance or approval. Or perhaps the other Hogwarts professors are witnesses to the whole event, adding to the drama and the consequences that Hermione might face for standing up to Snape.
Hermione is the central figure here as she is the one driving the action. She is likely to be portrayed as a bit more feisty and assertive than in the original books. Snape is also a main character as he is the target of Hermione's outburst. However, other characters like Harry and Ron might also make appearances. They could be the ones who witness Hermione's confrontation with Snape or even be involved in the events that lead up to it. For example, Harry might tell Hermione about something unfair Snape did, which then prompts her to act.
One possible plotline could be that Hermione stands up to Snape for constantly being unfair to Gryffindor students. Maybe she discovers some misinformation he has spread about her friends and confronts him publicly in the Great Hall, causing a stir among the students and teachers alike.
In these fanfictions, the main characters are the ones that drive the story forward. The son is likely to be a complex character, having traits from both Snape and Hermione. Snape, with his brooding and mysterious nature, and Hermione with her logical and tenacious personality. Their relationship as parents to this son forms the core of the story. And then there are other characters from the original Harry Potter universe who might be involved, such as Dumbledore (even if only in memories) who could have an influence on the son's understanding of his father's past.
Madame Maxime, the headmistress of Beauxbatons, would surely play an important role. She might be initially skeptical of Hermione but later come to respect her. Also, there could be a young male wizard at Beauxbatons who is intrigued by Hermione's intelligence and Hogwarts - style magic. He could try to learn from her and in the process, they become friends and face challenges together in the school.
Obviously, Severus Snape is the central character. He is the one who travels back in time, so all the actions and changes are centered around him. But other important characters often include Lily Evans. Since Snape had a deep connection with her, he might try to interact with her in different ways to change the past.
The main characters are obviously Snape and Hermione. Snape is a complex and often misunderstood character in the Harry Potter universe. Hermione is the brilliant, book - smart witch. In this fanfiction concept, they are brought together by the marriage law.
Snape, on the other hand, would be his usual brooding self, but perhaps more on edge because of Hermione's newfound boldness. He is still the strict and somewhat mysterious professor, but now he has to deal with a student who doesn't cower at his glares or biting remarks. His pride might be a bit bruised as Hermione challenges his authority.
One common pairing is with Severus Snape. In some fanfictions, when Hermione goes back in time, she may interact with a younger Snape and they could form an unexpected bond. Another is with Tom Riddle. Their interactions can be really interesting as Hermione tries to prevent him from turning into Voldemort.
Obviously Hermione herself. There could also be the military school instructors, who might be strict and tough. And some of her classmates, perhaps some are friendly and others are rivals.
Ron could be one of the main characters. Since he is Hermione's boyfriend and Ginny's brother, he might be caught in the middle of their conflict. He could try to play the peacemaker or end up taking sides, which would further complicate the situation.
Bellatrix Lestrange could also be a character who interacts with Snape. If Snape goes back far enough, he might try to influence Bellatrix's path and keep her from becoming such a devoted Death Eater. This could have a major impact on Voldemort's power and the overall balance of the wizarding world.