Well, it could start with Percy and Nico being framed for stealing a powerful artifact. Their so - called friends, without really investigating, immediately assume they are guilty. This betrayal makes them feel isolated and angry. They then decide to go on their own to find the real culprit and in the process, discover a deeper conspiracy that goes beyond just their personal betrayal, involving the very fabric of the demigod world.
In a 'Percy and Nico are betrayed' fanfiction, perhaps they are betrayed by the gods. The gods, fearing their growing power, might spread lies about them among the demigods. Percy and Nico then have to fight not only against the false accusations but also the demigods who turn on them. They would have to find a way to clear their names and prove their loyalty.
The camp leaders might betray them. If there is a power struggle within the camp, and Percy and Nico are seen as threats to the current leadership's power, the leaders could set them up. They could make it look like Percy and Nico are breaking camp rules or endangering the other campers, which would lead to the rest of the camp turning against them.
It could be a jealous demigod. Maybe someone who is envious of Percy's popularity and Nico's unique powers. This person might see an opportunity to get rid of them and take their place in the demigod hierarchy.
Well, they could be betrayed by someone they trusted deeply, like a fellow demigod. Maybe this person spreads false rumors about them, leading to their isolation within the demigod community. The three of them would then have to struggle to clear their names and find out who really set them up.
Well, they might lose trust in their friends. For example, if they were betrayed by someone they considered a close ally in the demigod world, like a fellow camper at Camp Half - Blood. Percy could become more withdrawn, as he has always been a bit of a loner at heart. Thalia might turn bitter and angry, using her skills as a hunter more aggressively. Nico, being the son of Hades, could potentially be pushed towards using his darker powers in retaliation, perhaps even seeking vengeance in the Underworld's way.
One possible reason could be jealousy among other characters. Maybe there are those who envy Percy's powers and leadership, Jason's status as a hero, or Nico's unique abilities. Another reason might be a misunderstanding. For example, they could be wrongly accused of a crime they didn't commit, which leads to others turning against them.
One possible plotline could be that Percy, Thalia and Nico are betrayed by their closest friends within the demigod community. Maybe they are framed for a crime they didn't commit, like stealing a powerful artifact. This could lead to them being hunted by their own kind. They would then have to go on the run, trying to clear their names while also facing various monsters that are after them because of the false accusations.
Well, it could be that Percy yells at Nico because he feels Nico is being too reckless in a dangerous mission. Maybe Nico is about to do something that could endanger the whole group, and Percy, being the protective type, loses his temper.
In this fanfiction, perhaps Percy adopts Nico after Nico has been ostracized by the other demigods. Percy realizes that Nico needs a safe space. So he offers his home. As time passes, they start to understand each other better. Nico might open up about his past traumas to Percy, and Percy would use his own experiences to help Nico heal and feel like he belongs.
In a fanfiction about their betrayal, it could be that they are betrayed by a new character who infiltrates their group. This new character might seem friendly at first but then turns on them to further their own secret agenda, perhaps related to an ancient prophecy. Percy, Nico and Thalia would then have to figure out how to stop this new threat while also clearing their names.
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.