Well, the fanfiction might show Percy being betrayed in a very personal way. For example, a god he trusted deeply, like Poseidon, could turn against him for some political reason among the gods. Percy would then be heartbroken and angry. He might embark on a journey to find a new purpose, away from the world of the gods. Along the way, he could meet new characters who help him see the true nature of the gods and himself.
Well, it could start with Percy being framed for a crime he didn't commit by the gods. This false accusation makes him feel extremely betrayed. He then has to go on the run while trying to prove his innocence. Along the way, he meets other outcasts and together they form a resistance against the gods. They might try to find a way to hold the gods accountable for their actions and create a new order where demigods are treated more fairly.
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.
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.
One possible plotline could be that Percy discovers his so - called friends have been secretly working against him all along. Maybe they spread false rumors about him, which makes everyone in his world turn against him. He then has to go on a journey alone to clear his name.
Perhaps in the fanfiction, Percy is influenced by some dark magic or a curse that makes him betray the son of chaos. The son of chaos then has to decide whether to forgive Percy or seek revenge. The story could also explore how their friends and allies are affected by this betrayal and whether they side with Percy or the son of chaos.
Perhaps in the fanfiction, Percy's death is a sacrifice that was misinterpreted. The gods thought it was necessary for some greater good, but it actually throws the world into chaos. His friends then have to find a way to bring him back and restore order.
He could lose his powers. Since his powers often come from the gods in some way, if they betray him, they might take them away. This would leave him vulnerable and feeling lost.
In some fanfictions, a love triangle could be involved. For instance, there could be another character who also has feelings for either Percy or Thalia. This creates tension and conflict, which in turn makes their journey to falling in love more complex. They have to overcome jealousy, misunderstandings caused by the third party, and also figure out their own feelings while dealing with external pressures.
One possible plotline could be that Poseidon, under some sort of dark influence, publicly disowns Percy. This would leave Percy feeling completely alone and betrayed, as his father's support had been a major part of his identity. He might then have to struggle not only with the regular threats he faces but also with the emotional turmoil of his father's betrayal. Another plotline could involve Poseidon stealing Percy's powers for some self - serving reason, perhaps to gain more power in the pantheon, forcing Percy to find new ways to survive and fight.
Well, it could be that Hestia betrays Percy for power. In the fanfiction world, she might see Percy as a threat to her own influence among the demigods or the gods. So she makes a deal with another powerful entity to get rid of Percy. For example, she could give false information about Percy's next move to a group of monsters, causing them to ambush him.