One possible reason could be a misunderstanding. Maybe Percy was wrongly accused of something, like stealing an important item in the fanfiction world, and Sall, being impulsive, kicked him out without proper investigation.
It might also lead to character development. For Sall, this action could show his or her flaws and lead to a journey of self - discovery where he or she realizes that kicking Percy out was a mistake. And for Percy, being kicked out could make him stronger and more determined, and he may come back with new skills or knowledge to change the situation in the fanfiction.
It could be related to his past traumas. All the battles he's been through, the losses he's suffered, might be weighing on him and he doesn't know how else to deal with the emotional pain.
It could be that the writer wants to explore the consequences of extreme distress in the context of the story world. Maybe they want to show how Percy's friends would react to such a situation, or perhaps they are using it as a plot device to create a very emotional and impactful story arc. Also, it might be a way to raise awareness about mental health issues in a fictional context, although this is a rather extreme way to do it.
Perhaps Annabeth made a decision without consulting Percy that put him in danger. In the fanfiction world, this could lead to her feeling guilty and apologizing. For example, if she led their group into a trap because of her over - confidence, she'd realize her mistake and say sorry to Percy.
Well, in fanfiction, one reason could be the loss of his friends. Percy has been through so many battles, and if he loses someone close like Annabeth or Grover, it could send him into a deep depression. Another reason might be the burden of his prophecies. He's constantly expected to save the world, and that kind of pressure can wear a person down over time.
Maybe he was hit by some magic or a spell that affected his memory. It could also be due to some sort of trauma he experienced that made his mind block out his memories of Annabeth.
It could also be due to extreme exhaustion. Harry often gets involved in intense battles or has to endure long periods of stress. For example, if he's been fighting multiple foes continuously without a break, his body and magic might give out, leading to him passing out.
Perhaps Percy was kicked out because of a prophecy that the camp elders misinterpreted. They thought that Percy's presence would bring great danger to the camp, so they made the hasty decision to expel him. It could also be that there was some sort of political intrigue within the camp. Some powerful figures at the camp might have seen Percy as a threat to their power and influence, and so they fabricated reasons to get him kicked out.
Well, one possible reason could be that Percy made a really stupid decision without consulting Annabeth first. Like, if he went off on a dangerous mission on his own when they were supposed to be a team. Annabeth is a very strategic person and she might feel betrayed or extremely frustrated by such actions.
Maybe he feels betrayed by the Olympians. They often have their own agendas and don't always consider the well - being of demigods like Percy. For example, they might send him on dangerous quests without proper support.