One possible reason could be a misunderstanding. Maybe Harry is led to believe that Dumbledore has been hiding something crucial about his parents' death or Voldemort's return. For example, if Harry discovers some encrypted files in Dumbledore's office that seem to suggest Dumbledore had a prior deal with Voldemort, it could lead to a fight. Another aspect could be related to power. If Harry feels that Dumbledore is being too controlling over his actions and the use of his powers, he might lash out. In the wizarding world, power struggles are not uncommon, and Harry, as a powerful wizard in his own right, might want to assert his independence.
Harry's magic is more instinctive and raw, often fueled by his emotions. So when he fights Dumbledore, his spells would likely be powerful but less refined. For example, he might cast a powerful Patronus in a fit of rage, which could be used as an offensive weapon rather than just for defense against Dementors. Dumbledore, on the other hand, has years of experience and knowledge. His magic would be more precise and strategic. He could use spells like 'Sectumsempra' but with better control, perhaps using it to disarm Harry rather than seriously harm him.
It could be that Harry finds out about Dumbledore's secrets regarding the Deathly Hallows. If Harry thinks Dumbledore was more interested in the Hallows for his own purposes rather than for the greater good, it might make him hate Dumbledore.
In the 'Harry Potter' fandom, this would be a very controversial concept. Dumbledore is often seen as a mentor and a powerful, positive figure. Having Harry Potter destroy him goes against the general perception of their relationship in the original series. However, in the realm of fanfic, some might explore such a dark and alternative take as a way to examine different character arcs and what - if scenarios, but it would likely be met with a lot of resistance from purist fans.
In some fanfics, Dumbledore having 'babies' is a very strange and often out - of - character concept. Usually, if this idea is explored, it might be in an alternate universe kind of setting. Some fanfics may use it as a shock factor or to create a really different kind of family dynamic within the wizarding world. But it's not a common or canon - like concept at all.
Hermione might support Harry if she also sees some flaws in Dumbledore's leadership. She is very logical and if Harry presents her with solid evidence, she could side with him. For instance, if Dumbledore's actions are putting students in danger in some way, Hermione would want to protect her fellow students.
No. The official 'Harry Potter' story by J.K. Rowling doesn't have any such plot where Dumbledore sells Harry fanfic. It's likely a fan - created or very non - canonical idea.
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.