Well, Sirius Black could be a character in this fanfiction. Since he was Harry's godfather, he would be extremely concerned about Harry's abandonment and would do everything in his power to rescue him. Luna Lovegood might also show up. Her unique perspective on magic could offer Harry new ways to cope with his situation. Neville Longbottom could be another character. He and Harry have a bond, and Neville might offer his support. Additionally, some fanfictions might introduce new original characters, like a mysterious old wizard who lives in the Forbidden Forest and takes Harry in after his abandonment.
Hermione would likely be one of the characters. She's Harry's best friend and would probably try to find him and help him out. Ron might also be there, as he's always been by Harry's side. Dumbledore could be another character. He might be trying to keep an eye on Harry from afar, or perhaps he has a plan for Harry's new situation. Hagrid would also be a likely character. He has a soft spot for Harry and would want to make sure he's okay. And of course, the Dursleys themselves might make appearances, either to continue their mean - spirited ways or to have a change of heart.
Obviously, Harry Potter is one of the main characters. He is the one who is being accepted by the Dursleys. Then there are the Dursleys themselves - Vernon, Petunia, and Dudley. Vernon is the strict and often grumpy uncle, Petunia is the aunt who has always been envious of Lily (Harry's mother), and Dudley is the spoiled cousin. Their interactions with Harry will be central to the story as they shift from their previous negative attitude towards acceptance.
Obviously, Harry Potter himself is the main character. He is the one with the motivation to fight against the Dursleys due to their years of mistreatment.
His friends from Hogwarts like Ron and Hermione. They are always by his side and would probably be more than happy to help Harry get revenge on the Dursleys. They might use their magic skills together to create some really interesting revenge scenarios.
Obviously, Harry Potter himself is the main character as he is the one getting back at the Dursleys. The Dursleys - Uncle Vernon, Aunt Petunia, and Dudley - are also main characters as they are the targets of Harry's revenge.
The main characters would be Harry Potter without a doubt. Since he is the focal point of the story as he is chained up. The Dursleys are key characters too. Vernon Dursley, with his mean - spirited nature, Petunia, who has always been cold towards Harry, and Dudley, who might have a change of heart during the story. And of course, we can't forget about Hedwig. She could be a crucial character, perhaps trying to bring help to Harry or at least provide some comfort while he is in such a dire situation.
Dumbledore could be a savior in this fanfiction. He has the power and the wisdom to step in and help Harry. He might have been waiting for the right moment to remove Harry from the Dursleys' influence. Also, there could be a new character, like an old and powerful wizard who has been in hiding but senses Harry's distress and comes to his aid. This wizard could have some unique magical abilities that can protect Harry and help him grow into a powerful wizard himself.
Other characters could include his professional Quidditch teammates. There might be a tough but fair captain, a cocky star player who initially doesn't get along with Harry, and a kind - hearted newbie who looks up to Harry. Then, of course, there could be rival players from other teams. These could be the typical antagonists on the pitch, always trying to outwit Harry during the games.
Harry is the central figure for sure. Neville Longbottom could play a role. He might be one of the few who know where Harry is hiding and is trying to protect the trunk from being discovered. Hagrid could also be involved. He might bring Harry some food and supplies while he's in the trunk. And there could be some mysterious old wizard or witch who has some connection to the trunk and its magic.
Obviously, Harry Potter himself is the main character. His friends like Hermione and Ron are likely to be there. Hermione might offer her intellectual support and advice on raising the child. Ron could be there for some comical relief and also to provide a male friend's perspective. Harry's godson Teddy Lupin could also be an important character, as he might be someone Harry looks to for inspiration on raising a child without a traditional family setup.
Obviously, Harry himself. And his best friends Ron and Hermione would surely be there. After all, they have been through so much together with Harry.