It could be that Hogwarts is trying to keep track of the cultural impact of the Harry Potter series. Fanfiction is a big part of the fandom culture, and Harry's death is a very significant event in the original story. By observing how fans handle this event in their own fictional works, Hogwarts (again, conceptually) can better understand the evolving relationship between the official story and the fan - created content.
One possible reason could be a dark turn in the story. Maybe Harry is under the influence of a dark magic or a powerful and evil entity that makes him lose control and start to destroy Hogwarts. For example, if he was possessed by a powerful dark spirit that wanted to eradicate the symbol of the wizarding world's good, which is Hogwarts.
It could be that there are unforeseen circumstances in the Triwizard tasks. For example, the magical creatures or the challenges are far more dangerous than expected. The Triwizard maze might be filled with deadly traps that are not properly controlled, and Harry could be caught in one of them, leading to his death.
Maybe he leaves because of a conflict with the Hogwarts staff. If the new headmaster or some teachers start implementing rules that Harry believes are wrong or unfair, like restrictions on defensive magic classes, he might decide to leave in protest.
One possible plot could be that the students and teachers at Hogwarts watch Harry's memories of facing Voldemort in the graveyard in 'Goblet of Fire'. They might be shocked and sympathetic, and it could lead to a greater understanding of Harry's burden. Another plot could involve Harry's memories of the Dementors affecting him, and as they watch, they figure out ways to help him better combat the Dementors' effects in the future.
In the world of Harry Potter, Hogwarts is a school, not a sentient being that can 'watch' fanfiction. However, students at Hogwarts might be interested in reading or writing Harry fanfiction as a form of creative expression related to their magical world.
No, Hogwarts is a building, not a sentient being with the ability to read in the traditional sense. It has magic and a kind of awareness, but not in a way that it can pick up a fanfiction and read it.
One possible reason could be that he was under the influence of a powerful dark magic or a curse that made him lose control. Another reason might be that he was tricked into believing Hogwarts was a threat to the wizarding world in some extreme way. Maybe a powerful enemy manipulated him to think that destroying Hogwarts was the only way to save everyone.
One reason could be to give him a stronger connection to Hogwarts. As the heir, he might have special privileges or knowledge about the school. Another reason is to add a new dimension to his character. It makes him more than just a student who defeated Voldemort.
One reason could be a surprise attack by Voldemort or his Death Eaters. Maybe they found a way to bypass all the protection spells around Harry and launched a sudden, fatal assault.
It could also be that the fanfic might interfere with the way he wants his story to be remembered. His adventures at Hogwarts were real and important to him, and when fanfic changes the narrative, it's like his story is being disrespected. For example, if a fanfic portrays him as cowardly when he was actually brave, that would surely make him dislike it.