In a fanfiction where they go to high school, Percy would likely be popular for his heroic deeds and good looks. He might join the swim team and break all the records. Thalia could be the cool girl who rides a motorcycle to school and gets into trouble for parking it in the wrong place. Nico would be the mysterious new kid. There could be a plot where they have to team up to stop a monster that is lurking in the school basement.
Well, one possible plot could be Percy and Nico having to deal with typical high school problems like bullies. Percy might use his water powers in a discreet way to stop them. Nico could be the mysterious loner at first but then make some real friends as he shows his cool powers. And they might also have to hide their demigod identities from the normal students.
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 Percy could become more withdrawn, as he has always been a bit of a loner at heart.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.
In the fanfiction, they could be given important missions. Maybe they are tasked with restoring balance in a part of the Chaos realm that has been thrown into disorder. Percy's leadership skills, Thalia's combat experience, and Nico's knowledge of the underworld could all be put to good use. They would have to work together, which might not be easy at first given their different personalities. But as they face challenges, they would grow closer and become a more effective team.
They could be sent on epic quests by Chaos. Maybe they have to retrieve some powerful artifacts that were lost in the chaos of creation. Along the way, they would face numerous challenges and meet all kinds of strange creatures. Percy would use his strategic thinking, Nico his knowledge of the underworld, and Thalia her leadership skills to overcome obstacles and make their way towards their goal.
In fanfiction, they might have an epic adventure. Percy could use his water powers to protect them if they encounter any danger. Thalia with her lightning might strike down foes. Nico could summon the dead to get information. Rhea might offer them some ancient wisdom or a special quest to save the world.
A powerful monster from the demigod world that has a vendetta against Percy and Nico could be the main antagonist. It disguises itself as a teacher or a student and slowly starts to manipulate things in the school. It tries to isolate Percy and Nico from their friends and then attack them when they are at their weakest.
The main plot could revolve around fixing a mistake in the past that has led to a distortion in the present. For instance, something might have happened in the past that changed the balance between the different camps of demigods. Percy, Thalia and Nico go back to set things right. They'd encounter different cultural and technological aspects of the past time period. And they would likely face opposition from those in the past who don't understand their motives or are being influenced by the very thing they are trying to correct.
Well, it would be quite chaotic. Percy could teach a water - based magic class, perhaps something related to controlling water elements. Thalia, with her electric powers, might teach a class on lightning - like spells. Nico, being the son of Hades, could teach about the darker aspects of magic, like dealing with the undead. But they would also have to adapt to Hogwarts' rules and traditions which would be a hilarious and challenging process.
They could be like siblings. Percy and Thalia might act as the older siblings, protecting and guiding Nico. Percy, with his leadership skills, and Thalia, with her combat abilities, would be great at looking out for the younger Nico. They could also be like cousins, with a close - knit bond but still having their own individual family heritages that sometimes create interesting dynamics.
Perhaps it's a fanfiction focused on their relationships. They might form an unexpected bond in the story. Nico, who has often been a bit of an outcast, could find real friendship and acceptance from Percy and Thalia. They could start out on a simple quest, like finding a lost artifact, and during this journey, they learn more about each other and grow closer as friends.