Hermione is a must. Her intelligence and extensive knowledge of magic and Hogwarts rules would be invaluable. Ron would be involved too. He's Harry's close friend and has a bit of a mischievous streak himself. Fred and George Weasley are very likely to be part of it. They are known for their love of pranks and their dislike of authority figures like Umbridge. Luna Lovegood could also be included. She has a unique perspective and might come up with some really out - of - the - box ideas for Harry's revenge on Umbridge. Plus, her presence would add an interesting and somewhat dreamy element to the whole revenge plot.
In some fanfictions, Harry might use his magic skills in a creative way to embarrass Umbridge. For example, he could make her signature pink outfits turn into ridiculous colors every time she tries to be authoritative. Another scenario could be that Harry reveals some of Umbridge's darkest secrets in front of the whole school, which would surely be a form of revenge as she values her reputation so much.
In some fanfictions, Harry discovers a long - forgotten magic charm that has the power to make a person's worst nightmares come true. He uses it on Umbridge, and she is so terrified by the nightmares that she runs away from Hogwarts. The charm could be something that is based on the person's deep - seated fears, and for Umbridge, it might be related to losing her power and being publicly shamed.
Fred and George Weasley are also favorites. Their mischievous nature can be amplified in fanfictions. They could create new and even more spectacular magical pranks specifically aimed at Umbridge, like turning her office into a never - ending maze of trick stairs and hidden rooms filled with various magical creatures that drive her crazy.
Another idea is a time - travel fanfiction. Harry goes back in time and has to deal with Umbridge when she was a student. He tries to change her path so that she doesn't become the horrible person she is in his time. This could involve him befriending her and showing her the value of kindness and freedom.
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.
Obviously, Harry Potter himself is the central figure. His friends like Ron and Hermione would also be involved. They would support Harry in his revenge plans, with Ron providing his loyalty and Hermione using her intelligence to strategize. Ginny Weasley might also be part of it, as she is Harry's love interest and a strong - willed witch in her own right.
Some fanfictions might have Harry getting revenge on the Ministry of Magic for their incompetence and corruption. He could expose their wrongdoings to the wizarding public and bring about a new era of transparency and fairness in the magical government.
In a 'Harry Potter gets revenge on Dumbledore' fanfiction, Harry could find out that Dumbledore knew about certain threats to his life but didn't do enough to protect him. So, Harry decides to get revenge by undermining Dumbledore's influence at Hogwarts. He might start by convincing the other students that Dumbledore isn't as infallible as they thought. He could do this by revealing some of Dumbledore's past mistakes. Then, he could work on getting the school governors to question Dumbledore's leadership, gradually chipping away at his power and status within the wizarding community.
Perhaps Harry uncovers a conspiracy where all his friends, the teachers at Hogwarts, and even the Ministry of Magic were in on a plot to control him. He then decides to take revenge in a very calculated way. He starts by sabotaging the Ministry's operations secretly. He might use his invisibility cloak to move around undetected and cast spells that disrupt their meetings or plans. For his friends, he could play mind games, making them feel guilty about their actions without revealing his true intentions at first.