Helga Hufflepuff is often underrated. In fanfiction, she could be explored more deeply. She was known for her kindness and inclusivity, but there could be more to her story. Maybe she had some secret adventures that haven't been told yet.
One underrated character is Luna Lovegood. In fanfiction, she can be developed even more. Her unique perspective and oddball ways can be explored in different scenarios. For example, she could be the key to solving a mystery that even Hermione can't figure out. Another is Neville Longbottom. He has so much potential in fanfiction to be more than just the shy boy who grew into a hero. Fanfics could show his adventures during the summer holidays or his own secret magical experiments. And then there's Kreacher. He's often overlooked, but in fanfiction, his loyalty and knowledge of the Black family secrets could be used in really interesting ways.
Neville Longbottom is another possible heir. He has a strong connection to Gryffindor through his family's long - standing association with the house. His growth from a shy and clumsy boy to a brave and powerful wizard could be part of a story where he is the heir of the founders. His ability to stand up to the Death Eaters in the final battle shows his hidden strength, which could be related to the founders' magic.
Often, the main characters would be the heirs themselves. There could be a character who is the heir of Gryffindor, perhaps a young student who has always shown great courage and a sense of justice. Another main character might be the heir of Slytherin, who at first seems a bit of an outcast because of the negative reputation of Slytherin but turns out to have a complex and important role.
Helga Hufflepuff is often quite popular. She represents kindness and loyalty, and in fanfiction, she might be portrayed as the one who keeps the founders together during their disagreements. Her character can be explored more deeply, like her backstory and how she came to value hard work and fairness so much.
Sometimes, the magical creatures that were around during the Founders' time can be popular characters in these fanfictions. For example, a phoenix that was a companion to one of the Founders and played a significant role in a particular event. They bring a touch of magic and mystery to the story and can be really engaging for readers.
Obviously, the four founders - Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw and Salazar Slytherin are main characters as they are being reborn. They bring their unique personalities and magical abilities back to the story.
I think in addition to the founders, characters like the first students they admitted can be quite popular. For example, if there was a particularly talented or mysterious first - year student in the fanfiction. Also, any descendants of the founders that might be introduced in the story could draw a lot of attention. They often carry on the legacies and sometimes the secrets of their ancestor founders.
The apprentice is obviously one of the main characters. They are likely to be a young wizard or witch with great potential. Then there might be characters representing the different houses of Hogwarts, like a descendant of Gryffindor who is a mentor to the apprentice. There could also be a rival apprentice who has different ideas about the founders' magic.
One idea could be exploring the relationships between the four founders before Hogwarts was fully established. For example, how did they meet and decide to build a school together? Another could be delving into the creation of the sorting hat and the initial sorting criteria. Maybe there was a big debate among the founders about it.
Helga Hufflepuff is also quite popular. She is often portrayed as the warm - hearted and nurturing founder. In time travel fanfics, she can be a source of comfort and wisdom for the time - traveling characters, and her unique brand of magic might be explored more deeply.