In the fanfiction world, their fight could stem from a misunderstanding. Albus might misinterpret Harry's actions as over - controlling when in fact Harry is just trying to keep him safe. Or perhaps there's a prophecy or a magical artifact that causes a rift between them. Albus may think that Harry is being selfish in handling the situation regarding the artifact or prophecy, while Harry believes he's doing what's best for everyone, especially Albus.
One possible reason could be differences in their views on magic. Maybe Albus wants to explore a more radical or different approach to magic compared to Harry's traditional views. Another reason might be the pressure Albus feels living in his father's shadow. He could be lashing out in an attempt to assert his own identity.
Well, it could be that Albus has gotten involved with some bad influences at Hogwarts. These new friends or ideas might put him at odds with Harry. Harry, on the other hand, being a protective father, would naturally oppose Albus's new direction. It could also be that there are secrets from Harry's past that Albus discovers and he feels betrayed, leading to a fight between them.
Some fanfiction writers may have a different vision for Harry Potter's character. They might see him as more of a diplomat or a healer within the wizarding world, rather than a fighter. So, they write stories that reflect this different view of the character, where he uses his wits and other skills rather than engaging in physical or magical combat.
One reason could be secrecy. If Harry finds out that Dumbledore has been keeping major secrets from him all along, like about his family or his true role in the wizarding world, he might start to hate him. Another reason could be manipulation. If it seems that Dumbledore has been manipulating Harry's actions for his own gain, that would be a valid cause for hatred in fanfiction.
Maybe Albus has done something dangerous or disobeyed Harry's instructions. For example, if Albus got involved with some dark magic related stuff without Harry's knowledge, that would surely make Harry yell at him.
There could be a fanfiction where Albus Severus Potter gets transported back in time to the era of his father's youth. He could witness the events that Harry went through first - hand, but also accidentally change some small things that have big consequences for the present time. He then has to find a way to fix the timeline without completely erasing his own existence.
He could also cry because of problems with his friendships. Maybe he has a falling out with his best friend over something silly but it really affects him deeply. In fanfiction, this is a common scenario that shows his emotional side.
One reason could be jealousy. Maybe Albus has some special ability or is getting more attention from their parents. Another could be that James is just following in the footsteps of the old school bullies he might have known, thinking it's normal behavior. Or perhaps he sees Albus as too different from what he expects a Potter to be.
One reason could be a powerful dark magic spell cast upon him by a new villain in the fanfiction world. This spell might be designed to make him disappear from the wizarding world entirely.
One possible reason could be that a powerful dark magic spell has been cast on him. Maybe a new dark wizard or witch, created specifically for the fanfiction, has found a way to make him vanish to cause chaos in the wizarding world. Another reason might be that Harry has chosen to disappear himself. Tired of the constant attention and danger, he decides to go into hiding, perhaps using some long - forgotten magic or a powerful magical object to conceal his presence.
It could also affect their relationship with other family members. For example, Ginny might step in to mediate between them, or it could cause tension within the family as a whole. If Albus feels unjustly yelled at, he might turn to other family members for support, which could create some family drama.
Maybe he's curious about different interpretations of his own story. In fanfictions, his character might be in new and exciting adventures that the original books didn't cover.