It could be that Percy has some sort of curse on him that makes his life a living hell. This curse could be slowly draining his life force or making him do things he doesn't want to do. So, he wants to die to break free from it. In the fanfiction, his friends might be trying to find a way to break the curse while Percy is constantly fighting his own internal battle of whether to just end it all or keep fighting.
One possible plotline could be Percy struggling with some form of depression or hopelessness that makes him want to die. Maybe he's lost someone dear to him, like a friend or family member, and he can't see a way out of his grief. Another could be that he's been through so many traumatic events that he feels like death is the only escape. For example, if he's constantly in battles and has seen too much death and destruction around him.
Perhaps Percy discovers that his very existence is putting others in danger. So, in an act of self - sacrifice, he wants to die. He might think that if he's out of the picture, his enemies will stop targeting his loved ones. In the fanfiction, this could lead to a journey where he tries to figure out a way to end his life in a way that won't cause more harm, or he could be on a search for someone who can take his powers away so that he becomes a non - target.
One reason could be the overwhelming burden of his demigod duties. Constantly facing dangerous monsters and quests can take a toll on his mental state. He might feel like he can't escape this never - ending cycle of danger and responsibility.
One possible plotline could be that Percy has been betrayed by his closest friend. Maybe this friend revealed a big secret of Percy's, and now Percy feels isolated and heartbroken. He might start to question his relationships and his place in the world.
One possible plotline could be Percy's friends trying to break him out. They might have to overcome various obstacles like guards, traps, and security systems within the prison.
Well, perhaps in the fanfiction, Annabeth betrays Percy's trust in a relationship way. She could start seeing someone else and use Percy's secrets against him to make herself look better in front of the new person. Or she might side with a group that Percy is against, believing their lies and false promises over Percy's warnings. This could lead to Percy feeling completely alone and having to find new allies.
Another plotline could involve Percy making new friends in the navy. These friendships could be tested during dangerous missions or when faced with internal conflicts within the naval unit.
Another plotline could be that Percy's reincarnation is part of a grand plan. There could be a powerful being or a prophecy that dictates his reincarnation. When he is reborn, he is fated to either save or destroy this new world he is in. Along the way, he meets friends from his past life who have also been reincarnated, but they don't recognize each other at first, and they have to go through a series of adventures together to remember who they really are.
One possible plotline could be that Percy sacrifices himself to save Artemis from a powerful and ancient enemy. Maybe there's a prophecy that foretells his death in order to protect her. Another could be that Percy is tricked into a situation where he has to give his life for Artemis to prevent a great disaster from befalling the world of the gods. And perhaps in his death, he becomes a symbol of heroism that changes the way the gods view demigods.
Perhaps Bianca has been poisoned, and Percy has to find a rare antidote within a time limit. He might have to journey to a far - off land, facing many challenges along the way. Or, it could be that Bianca has been lured into a trap by a false friend, and Percy has to expose the traitor and rescue her from the ensuing danger.
One possible plotline could be that Percy and Nico are betrayed by a close friend within the demigod community. Maybe they are framed for a crime they didn't commit, like stealing a powerful artifact from the gods. This could lead to them being hunted by other demigods while they try to clear their names.
Perhaps a plotline where Percy, as the daughter of Artemis, is chosen for a special mission. The gods, seeing her unique heritage, task her with something that no other demigod can do. It could be related to restoring balance in the world of the gods. Along the way, she has to deal with her own insecurities about not being a 'normal' demigod and prove herself worthy of the mission.