Perhaps Harry discovers some deep, dark secret about Umbridge that is related to the Dark Arts. He could use this knowledge to blackmail her into leaving Hogwarts. For example, if he found out that she had some connection to Voldemort's followers in the past, he could threaten to reveal it to the Ministry of Magic, which would surely be the end of her tenure at the school.
In another scenario, Harry could expose all of Umbridge's wrongdoings in a very public and embarrassing way. He might use the Marauder's Map to find evidence of her sneaky activities and then present it to the whole school, causing everyone to turn against her and forcing her to leave in disgrace. Harry has a lot of friends who would support him in this, like Hermione and Ron.
Well, perhaps in the fanfiction Harry finds out that Umbridge has been secretly working for Voldemort all along. He gathers evidence and presents it to Dumbledore and the other teachers. They are shocked and immediately decide that Umbridge can no longer stay at Hogwarts. Harry takes the lead in escorting her out of the school. Or maybe Harry uses his connection with the Order of the Phoenix to get support in getting rid of Umbridge. The Order members come to Hogwarts and together with Harry, they force Umbridge to leave because of her unjust and cruel treatment of the students.
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.
One possible storyline could be that Harry endures the torture but uses it as fuel to secretly plan a rebellion within Hogwarts. He might start to gather like - minded students who have also been victims of Umbridge's tyranny. Another could be that his friends, like Hermione and Ron, find out about the torture in a more indirect way and then they try to expose Umbridge's actions to the wizarding world. Or perhaps, Dumbledore finally steps in to put an end to the torture in a very dramatic and magical way.
One possible scenario could be when Lupin has to leave Hogwarts due to his werewolf secret being revealed more widely. He might cry because he has found a sense of belonging there, with his friends and students. He loves teaching and seeing the young wizards grow, and leaving all that behind is heart - breaking for him.
Perhaps in the fanfiction, Harry Potter's death occurs because he tries to rewrite a powerful magic spell that goes horribly wrong. He was always known for his bravery and willingness to take risks in the original series, so this could be an extension of that. His death would then be a tragic consequence of his own curiosity and desire to push the boundaries of magic.
One possible scenario could be that Harry is exiled due to false accusations of dark magic. Maybe the Ministry of Magic, fearing his power after the defeat of Voldemort, spreads lies about him being a threat. Another could be that he chooses exile to protect his friends from a new, unknown danger that is targeting him specifically.
Perhaps there was a dark wizard who was on the loose in the area where Harry lived. This wizard was attacking muggles randomly. Harry, being the Boy Who Lived with an inherent magical power, was able to disrupt the wizard's spell and it backfired, killing the dark wizard. This event could be a huge shock for Harry and his aunt and uncle, who have been trying to suppress his magic all along. It would also make his entry into Hogwarts even more complex as he has already had a major encounter with the dark side of the wizarding world.
In a more complex scenario, Bellatrix could be trying to use a dark magic ritual that would cause great harm to the wizarding world. Harry discovers her plan and has to engage her in a magical struggle. In the process, he manages to turn her own dark magic against her, which results in her death. This would show Harry's ingenuity and his ability to use the enemy's own weapons against them.
One possible scenario is that Harry discovers the Force during his time at Hogwarts. Maybe there's a hidden chamber or an old artifact that unlocks this power within him. Another scenario could be that he meets a character from a different universe who teaches him about the Force. For example, a rogue Jedi who has somehow ended up in the wizarding world.
One possible scenario could be that Harry discovers a hidden magical passageway in his tiny bedroom at the Dursleys'. It could be a secret portal created by a well - meaning wizard long ago to help any oppressed magical being in the Muggle world. Harry stumbles upon it while looking for a lost sock or something mundane. Another scenario might be that a group of friendly magical creatures, like house - elves, conspire to help him escape. They create distractions around the Dursley house, like making the pots and pans fly around and creating chaos, which allows Harry to slip away unnoticed.