Perhaps the plot could start with Percy feeling lost after all his demigod adventures. He decides to join the army to find a new purpose. Once in the army, he discovers that there are dark forces at work within the military itself. These forces are trying to use the power of the gods for their own evil gains. Percy then has to fight against this internal threat while also proving his worth to his fellow soldiers who are initially skeptical of him.
A great plot could be Percy being sent on a top - secret mission by the army. This mission could be related to some ancient artifact that has military applications but also ties to his demigod world. Along the way, he meets other demigods who are also in the military for various reasons. Together, they have to overcome not only military enemies but also mythical creatures that are after the same artifact.
One possible plot could be that Percy, with his battle experience from the Greek world, quickly rises in the ranks of the Chaos Army. He might bring new strategies inspired by his demigod training, like using the element of water in unexpected ways during battles. His loyalty and sense of justice could also lead him to take on difficult missions for the Chaos Army, such as infiltrating enemy camps that are otherwise impenetrable.
In this kind of fanfiction, Percy might use his demigod powers in the military. For example, his ability to control water could be useful in various military operations like amphibious assaults. He could also use his combat skills learned from Camp Half - Blood to outperform regular soldiers.
One possible plot could be Percy facing a difficult mission in a war - torn area. He has to use his unique skills, perhaps some magical or extraordinary abilities he has, to outwit the enemy and complete the mission. For example, he might use his strategic thinking to lead his unit through a dangerous territory filled with traps set by the opposing side.
If Percy Jackson is leading the Chaos Army in fanfiction, one thing that could occur is that he forms alliances with other powerful forces. Given his reputation and the fact that he has friends in many different places, he could convince other groups to join his cause. He might also face challenges from within the army, as some members may not be used to his leadership style. However, Percy would likely overcome these challenges by proving himself through his actions and by showing that his way of leading is the best for the overall success of the Chaos Army.
Well, perhaps Percy could be disillusioned with his current situation in his normal world. He might see the chaos army as a way to break free from the constraints he's felt. He could start off as an outsider in the chaos army, having to prove himself.
Well, the plot might start with Percy being sent on a special mission by the gods. They need someone with his quick reflexes and sharp eyesight to be a sniper. Along the way, he has to deal with the moral implications of taking lives from a distance. He might also face challenges in terms of getting the right equipment and training. His friends could be initially skeptical of this new role for him, but as they see him succeed in various battles, they come to accept and rely on his sniper skills.
One possible plot could be Percy using his bike to travel across the country to find and protect other demigods. He could encounter various monsters along the way and use his biker skills, like sharp turns and high - speed maneuvers, to evade them.
One possible plot could be that a powerful enemy, let's say a dark sorcerer, has found a way to use the powers of the Greek gods against the supernatural beings in the Mikaelson universe. Percy Jackson is sent to investigate and ends up getting caught in the middle of the Mikaelson family drama. He has to use his skills as a demigod and his knowledge of Greek mythology to help the Mikaelsons defeat this new threat while also trying to keep his own identity and mission a secret from some of the more untrustworthy members of the family.
Maybe Percy Jackson somehow gets transported to the world of Stranger Things and has to fight the Demogorgon. He could use his water - controlling powers to try and defeat it, like dousing it with a powerful stream of water.
Well, in a 'Percy Jackson Endgame' fanfiction, the plot might involve Percy finally having to make a huge sacrifice to save not just the demigod world, but the entire mortal world as well. The other characters like Annabeth, Grover, and the rest of the gang would be trying to find an alternative solution while Percy is ready to give it all up. It could also include a race against time as some sort of dark prophecy looms over them.