A possible plot could be a competition among the demigods where Percy, as a 'Son of Ares' in this fanfiction, has to prove himself against other powerful demigods. The competition could include tasks like combat, strategy, and survival challenges. Along the way, Percy could learn more about the Ares - like qualities within himself and also form new alliances or rivalries.
A really cool plot could be Percy getting caught in an alternate dimension where Ares is the main god in charge. He has to find a way to survive in this new world, where the rules are different and he's seen as an outcast. Percy would need to use his wits and skills to navigate this strange place and find a way back home.
One plot idea could be Percy having to team up with the children of Ares for a special quest. Maybe there's a powerful ancient weapon that only the combined strength of Poseidon's and Ares' descendants can wield. Another idea is Percy getting caught in the middle of a feud between the Ares cabin and another cabin, and he has to find a way to make peace. Or perhaps Percy discovers he has some unexpected connection to Ares' lineage that changes his perception of himself and his powers.
A plot could involve Ares testing Percy in a series of challenges that are not just about physical strength but also about his mental and moral fortitude. For example, Ares creates illusions of Percy's friends in danger, and Percy has to make difficult decisions. This would explore Percy's character deeper and also show a different side of Ares as a sort of cruel mentor. Or perhaps a story where Percy is accidentally transported to Ares' domain during a battle, and he has to find a way to escape while also dealing with the war - crazed creatures there.
One idea could be Percy struggling to fit into Ares' violent and war - loving family. He might constantly have to prove himself in battles or challenges set by Ares. Another could be Percy having to deal with the other children of Ares being jealous of the attention he gets from their father. He could also be on a mission to redeem Ares' bad reputation among the demigods using his own unique skills and the powers he inherits from Ares.
One idea could be Percy struggling with the duality of his parents' natures. Ares' aggression and Aphrodite's love and beauty aspects could be at odds within him. For example, he might be in a situation where his natural inclination towards love and peace from Aphrodite clashes with the need for battle and aggression from Ares during a war between the camps. Another plot could involve Percy having unique powers due to his dual heritage. Maybe he can use love as a weapon in a way, like making enemies fall in love with each other and thus incapacitating them, which is a strange power coming from the combination of his parents.
Perhaps there's a mystery at Ares High School where strange things keep happening, like students getting sudden bursts of uncontrollable strength. Percy, suspecting it has something to do with Ares, investigates and discovers an ancient artifact hidden on campus that's causing the chaos. He then has to find a way to stop it without getting caught by the school authorities or Ares' minions.
One idea could be Percy having to hide his true parentage from the other demigods at Camp Half - Blood. He's constantly worried about being shunned or attacked if they find out. Another could be Percy using some of Medusa's powers in a unique way, like being able to turn enemies to stone briefly but with some unforeseen consequences. Maybe he has to go on a quest to find a way to control these new powers.
One idea could be Percy having to navigate the Underworld politics due to his relation to Hades. He might face challenges from other underworld creatures who don't trust him. Another could be Percy using his newfound powers as the son of Hades to fight against an ancient evil that threatens both the mortal and underworld realms. Or perhaps he has to deal with the stigma of being Hades' son in the demigod community and prove himself worthy.
A possible plot for a Percy Son of Pluto fanfiction could be that Percy is haunted by strange visions that seem to be related to Pluto's past. He decides to embark on a journey to find out the truth behind these visions. As he delves deeper into the mystery, he finds out that there is a forgotten prophecy about him that could change the balance between the gods and the demigods. He then has to gather allies, both from the surface world and the Underworld, to face whatever is coming.
The son could be cursed by a powerful being. Percy then has to find a way to break the curse. This could involve seeking help from old friends and new allies. Or perhaps the son has a premonition about a great danger coming to the world of demigods, and he and Percy have to convince the other demigods to take action before it's too late.