Padma Patil. She was one of the students chosen for the Yule Ball, but not much was explored about her. Fanfiction could give her a more complex personality, like she could be secretly researching ancient spells related to the Triwizard Tournament that might be useful to Harry or the other champions.
Winky the house - elf. She was briefly in the fourth year story but there's so much more that could be done with her. Maybe she has some secrets about the Dark Arts that she's been hiding because she's afraid of getting in trouble.
Pettigrew. He's often just seen as the traitor, but in fanfiction, you could explore his motives more. Maybe he was forced into his actions by some dark magic or a threat from Voldemort that no one knew about.
The house staff could be underrated characters. They've been around the Hawthorne family for a long time and surely know a lot of secrets. Focusing on them could add a whole new layer of intrigue to the story.
Rhonda Kazembe is quite an underrated character. She has a lot of potential for more development. Her skills in various areas could be explored further, like how she might use her knowledge in a different way to help the society in a new situation. Maybe she could be the key to solving a mystery that the others overlook.
Tye Longshadow is often underrated. In fanfiction, he could be given a more central role. His powers are really interesting and his backstory has a lot of potential for exploration. For instance, a fanfiction could focus on his journey to fully master his shadow powers and how he overcomes his insecurities related to being different from the more well - known heroes in the team.
Antoine could be a great character to focus on more. In Sonic SatAM crossover fanfiction, he could have a character arc where he overcomes his cowardice in a new and unique way. Maybe in a crossover with the Archie Sonic comics universe, he could learn some new combat skills from the more battle - hardened characters there.
Dende. He has great potential. In fanfiction, he could be given a more active role in the Parallel Saga. Maybe he discovers a new type of power related to the Namekian Dragon Balls that could turn the tides in battles. He's often overlooked but has a deep connection to the Dragon Ball lore.
Seamus Finnigan could be a great focus. He's often seen as just a side character, but in fanfiction, he could have his own moment. Maybe he discovers a new spell related to the Triwizard Tournament tasks that no one else knows about. He could use this spell to either help Harry or get himself into trouble while trying to prove himself.
One underrated character is Prentiss. He's often just in the background in the original, but in fanfiction, he could be the hero. Maybe he discovers a hidden power within himself that helps Peter and the gang. Another is Ted. He could be given more spotlight by having his own backstory explored, like how he ended up on the ship in the first place.
One underrated character who could have a bigger role is Seamus Finnigan. He's always been on the sidelines a bit, but in a 7th year au, he could be a key figure in the Gryffindor resistance against the Death Eaters at Hogwarts. His skills in charms and his Gryffindor courage could be put to great use. Also, Professor Trelawney could be more important. She might have a real, accurate prophecy in this au that she shares with Harry. Her knowledge of divination could be the key to understanding some crucial aspect of Voldemort's downfall, rather than just being seen as a bit of a joke like in the original story.
Cho Chang. In a parallel universe, Cho could be a more central character. Maybe she discovers a new type of magic that is related to her Asian heritage. This could make her a target for both the good and bad sides. She could also have a more complex relationship with Harry or other characters, not just as a love interest, but as a powerful witch with her own motives and goals.