Some of the students who have been through tough times at Hogwarts due to Voldemort's influence might also side with Harry. Neville, for example, has shown great courage and has his own ideas about how to deal with the dark forces. He might see Harry's defiance as a necessary step in the fight against the common enemy, and join him in his stand against Dumbledore if he believes it is for the greater good.
The Weasley family as a whole might also support Harry. They have always treated Harry like one of their own. Arthur Weasley, being an open - minded wizard, might understand Harry's perspective. Ginny, who is very close to Harry, would surely be on his side as well. They would see Harry as more than just a student defying a headmaster, but as someone fighting for what he believes is right.
Hermione Granger would surely be one of the first to support him. She's always been by his side, helping him with research and providing intelligent advice. Ron Weasley would also be there, being Harry's loyal friend through thick and thin. Neville Longbottom could be another supporter. He's grown into a brave and capable wizard, and he would stand with Harry in his new role. Dumbledore, if he were still alive in the fanfiction, would likely offer his wisdom and guidance to Harry as he takes on this new and important role.
Ron and Hermione are the most likely. They've always been by Harry's side in the original series. In the fanfiction, when Harry stands up for himself, they would surely be there. Ron might use his sense of humor to diffuse the situation if it gets too tense, while Hermione would back Harry up with her vast knowledge of wizarding laws and rights.
His friends, like Ron and Hermione, are very likely to support him. They've always been there for him in the original story, and in this fanfiction scenario, they would be even more important in his life. Hagrid could also be a great source of support. He has a big heart and has always cared about Harry.
Ron would also be there. He might start out a bit reluctant, but then get into it. He could be Harry's partner in physical challenges, like having races on broomsticks or wrestling magical creatures in a controlled environment for fitness.
For Harry, his friends like Ron and Hermione are likely to be his allies. They've always been by his side through thick and thin in the original series, so it's natural for them to support Harry in a confrontation with Dumbledore. Neville could also be an ally, given his growth and courage shown in the books.
Hermione might support Harry if she also sees some flaws in Dumbledore's leadership. She is very logical and if Harry presents her with solid evidence, she could side with him. For instance, if Dumbledore's actions are putting students in danger in some way, Hermione would want to protect her fellow students.
Hermione would be a likely candidate. She is Harry's best friend and is very intelligent. She could use her knowledge of spells and magic to come up with a plan to help Harry escape. For instance, she might create a diversion or find a way to disable the security around Dumbledore's area.
The main characters would be Harry and Dumbledore. However, the antagonists could also be important. If there is a new dark force in the fanfiction, they would be the ones Harry and Dumbledore are up against. Voldemort's remaining followers could also be part of the equation. Their actions could be what drives Harry to submit to Dumbledore's leadership, as they pose a significant threat to the wizarding world and Harry realizes he needs Dumbledore's guidance to face them.
Some of the younger students who looked up to Harry, like Neville, could support him. Neville has grown to be a strong and brave character. He might see Harry's actions as a way to make the wizarding world a better place. Also, those students who have felt wronged by Dumbledore's decisions in the past, perhaps in terms of school policies or safety, could come forward to support Harry in the court case.
Hermione would be a likely supporter. She is always loyal to Harry and if he presented her with evidence of Dumbledore's wrongdoings, she would probably side with him. She has the intelligence to help Harry strategize and find ways to expose Dumbledore. For example, she could use her research skills to dig deeper into Dumbledore's past.