The main character is usually the heir themselves. They could be an original character created for the fanfiction or a well - known character from the original series given a new twist. There are also often mentors from each of the houses the heir is related to. For example, a wise old Ravenclaw professor or a brave Gryffindor knight - like figure.
Typically, you'll see the heir, who is often a young wizard or witch. Then there are the friends and allies they gather along the way. Some might be from the houses they are heir to, like a Slytherin who helps them understand the more secretive side of their inheritance. There could also be antagonists, perhaps jealous students or even dark wizards who want to use the heir's power for their own evil purposes. The characters are often complex, with different motives based on their house loyalties or lack thereof.
The main character, the heir, is central. They might be a bit of an outcast at first, not fully fitting into any one house. Then there are the house heads or representatives who play important roles. For example, a Hufflepuff representative might teach the heir about the values of hard work and loyalty in relation to their inheritance. And of course, there are classmates, some of whom might be suspicious or curious about the heir's multiple - house status. These characters interact in various ways, creating drama and plot development within the fanfiction.