In certain fanfictions, Dumbledore's secrets are the root of the perceived betrayal. For instance, his secrets about the Deathly Hallows. If Harry discovers that Dumbledore had known more about the Hallows all along and didn't share this knowledge, which could have changed Harry's journey and decisions, it could be written as a betrayal. Harry may feel that he was used and misled by Dumbledore, and thus the idea of betrayal emerges in these fan - created stories.
In some fanfictions, Dumbledore might be portrayed as betraying Harry by withholding crucial information. For example, if he knew more about Harry's fate or the true nature of the threats he faced but didn't share it all. This could make Harry feel betrayed as he was left in the dark and had to face greater danger without full knowledge.
A common plot is that Dumbledore has been manipulating Harry from the start. He might have arranged events in Harry's life to lead him to a specific fate against Harry's will. For example, making sure Harry attended Hogwarts to be part of the fight against Voldemort.
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.
A common scenario is when Dumbledore lies about Harry's family history. If he hid important details about Harry's parents or their relationship with certain dark forces, Harry would feel betrayed. Another could be Dumbledore giving Harry tasks that were actually much more dangerous than he let on, like sending him into a trap unknowingly.
Well, Harry might outsmart Dumbledore by using his unique understanding of the magical world in ways Dumbledore doesn't expect. For example, Harry has a more direct experience with some dark magic items due to his encounters with Voldemort. He could use this knowledge to make decisions that seem counter - intuitive to Dumbledore but are actually more effective in a particular situation.
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.
One possible reason could be that Harry breaks school rules in the fanfiction. For example, if he ventures into the Forbidden Forest without permission. Dumbledore is strict about the safety of students and such disobedience might lead to punishment.
In a fanfiction, Dumbledore might steal out of desperation. Suppose there was a situation where a curse was about to be unleashed on Hogwarts, and the only way to stop it was by stealing a particular ingredient for an antidote from a place where it was not supposed to be taken. Dumbledore, seeing no other option, decides to steal it. His motive here is to save the school and its students, even if it means breaking the rules.
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.