It could be because of a deep-seated grudge or misunderstanding. Maybe Harry felt betrayed by Dumbledore's actions or decisions.
Well, it might be that some external force influenced Harry or there was a magical curse at play that made him do it against his will. Another possibility is that Dumbledore was seen as a threat to Harry's goals.
In some fanfictions, Dumbledore might bow out of respect for a powerful magical entity or a person with extraordinary abilities. It could also be a sign of his humility in the face of a situation where he realizes he is not the most knowledgeable or powerful.
Perhaps Harry was feeling betrayed or misunderstood and wanted to express his strong emotions directly to Dumbledore through a howler. This could be a way to make his point and demand a response.
In some fanfictions, female Harry Potter might hate Dumbledore because the author wants to create a different dynamic. Maybe Dumbledore's actions in the original story, like keeping secrets from Harry, are exaggerated in the fanfic. For example, if he withheld information that could have saved someone she cared about, it could lead to her hatred.
He might give Harry detention. Harry could be made to clean the trophies in the trophy room or help Hagrid with some difficult tasks in the Forbidden Forest under strict supervision.
In my opinion, Dumbledore would underestimate Harry Potter fanfiction. Fanfiction is a realm where fans take the original story and run with it in all kinds of directions. There are fanfictions that change the personalities of characters, create new storylines that deviate greatly from the original. Dumbledore, who is bound by the original narrative and his role in it, may not understand the significance of this new wave of creativity that fanfiction represents. He may see it as a distortion of the world he knows rather than a celebration and expansion of it.
It could be that Dumbledore has some strategic or protective reasons. Maybe the electives Harry chose initially could expose him to greater risks or prevent him from developing crucial skills needed later on.
Dumbledore might underestimate it because he's used to the 'official' version of the wizarding world. Fanfiction can be full of wild ideas that don't fit his traditional view.
It might make Harry more confident. With Dumbledore's training, Harry gains more knowledge and skills, which gives him the confidence to face challenges.
One reason is that fans like to explore different perspectives. In the original books, Dumbledore is presented as a wise and mostly benevolent figure. But some fans want to see what would happen if he had a darker side. It adds a new layer of complexity to the story.
Well, in certain Harry Potter fanfiction, Dumbledore can come across as insane. It really depends on the writer's interpretation and the direction they want to take the story. Some might do it for shock value, to create a more edgy or different take on the well - known character. However, the canonical Dumbledore was a highly intelligent and calculating figure, not insane.