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.
One possible plot could be that Harry discovers some long - hidden secrets about Dumbledore's actions during the war. Maybe he finds out that Dumbledore knew more about Voldemort's plans but didn't act in a way Harry thought was right. So, Harry decides to take him to court to expose the truth and seek justice for those who suffered because of what he believes were Dumbledore's missteps.
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.
I'm not sure specifically as I haven't read that exact fanfiction. But it could potentially be about Harry Potter having some sort of conflict with Dumbledore and taking actions against him. Maybe Harry discovers some dark secrets about Dumbledore that make him question his leadership and take steps to oppose him in the fan - created storyline.
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.
His friends like Ron and Hermione would surely support him. They have been through a lot together, and they believe in Harry's leadership. Also, the Weasley family in general would be behind him. They have always been on Harry's side in his battles against the dark forces.
Hermione is often one of the main supporters. Her intelligence and knowledge of magic are always at Harry's disposal. She can help him research spells and strategies when he takes charge of a situation.
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.
Maybe in the fanfiction, there is a misinformation or a spell that has corrupted Dumbledore's mind. Harry, being the hero he is, notices the change in Dumbledore's behavior. He decides to take down Dumbledore because he thinks it's the only way to save the wizarding world from the new, dangerous path Dumbledore seems to be leading them on. For example, Dumbledore might be making alliances with dark forces unknowingly due to the spell, and Harry has to stop him.
Dumbledore himself could be seen as the main antagonist in this scenario. Since Harry is set on taking him down, Dumbledore's actions, whether they are truly malicious or just misinterpreted, would be the main obstacle for Harry to overcome.
Well, he could use it to uncover secrets that Dumbledore might have left behind. Since Dumbledore was a very knowledgeable and powerful wizard, his wand could hold the key to certain mysteries. Harry might be able to access hidden chambers or knowledge that was previously inaccessible. However, taking the wand could also bring a great deal of trouble. There could be those who would want to take the wand from Harry, thinking he doesn't deserve it or that it should be in their possession for their own dark purposes.