The story could start with Percy being in a desperate situation. He is then approached by a mysterious figure who offers him a way out - become the assassin of chaos. Percy, having no other choice, accepts. As he embarks on this new path, he has to face his own moral dilemmas. He may find that some of the chaos he is supposed to fight is actually a part of a greater order that he doesn't understand. He also has to deal with the fact that his old friends might not trust him anymore now that he is associated with chaos.
Well, perhaps Percy starts off as an ordinary character but gets drawn into the chaos realm. He could be forced to become an assassin due to some threat to his friends or family. Maybe he discovers new powers that make him suitable for this role.
In this fanfiction, Percy could be an assassin who is on a quest to find a powerful artifact. This artifact was stolen by a rival group and is being used for evil purposes. He travels across different lands, using his assassin skills to gather information, fight off enemies, and finally retrieve the artifact to save the world.
Maybe the gods or powerful beings who are trying to maintain the current balance and see Percy's new role as a disruption. They would try to stop him from carrying out his assassinations in the chaos world.
Well, perhaps the story could start with Percy feeling disillusioned with the traditional order. He might be drawn to the chaos because he sees the flaws in the existing system. Then, as a general of chaos, he could start to gather a group of misfits who also believe in change. They'd likely face opposition from the forces of order, leading to some epic battles and tense stand - offs.
Well, he might gain incredible cosmic powers. He could have the ability to manipulate space, time, and matter at will. His appearance might change to something more otherworldly, with a glowing aura perhaps. And he could have a new level of wisdom, seeing the grand design of the universe.
One plot idea could be Percy being sent on a secret mission by the Chaos forces to infiltrate an enemy stronghold. He uses his skills and wits to gather intelligence without being detected.
Maybe in the fanfiction, Percy is on the verge of death in a battle. Chaos, who has been observing Percy for a while, decides to save him and adopts him. Percy then embarks on a journey in Chaos's realm. He could be trained by powerful beings there and form new alliances. His relationships with his old friends from his previous life might be strained as they don't understand his new situation, but he also gains new friends who are loyal to him because of his connection to Chaos.
Well, perhaps Percy could be learning some new and powerful combat skills from Chaos. Maybe Chaos teaches him to manipulate chaos energy in unique ways for battle.
Well, in a 'Percy meets Chaos' fanfiction, it might start with Percy being pulled into a strange dimension where Chaos exists. Chaos could be a formless entity that communicates with Percy telepathically. Percy has to learn to understand Chaos' motives, which could be to reshape the world Percy knows in a more chaotic way. Percy then has to decide if he wants to fight against Chaos or join it in some way.
Well, perhaps Percy would grow up with a very different set of values and skills. He might be more wild and unpredictable, having been raised by Chaos. Maybe he'd have powers that are more primal and less bound by the normal rules of the demigod world.
One interesting plot twist could be Percy being secretly trained by an ancient and forgotten god. This god might have a hidden agenda that Percy gradually uncovers throughout the fanfiction.