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 idea could be Percy struggling to fit into Ares' violent and war - like family culture. He's used to Poseidon's more fluid and adaptable ways. Another could be Percy having to face off against his new - found siblings in a sparring match to prove his worth to Ares.
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 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.
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 struggle with the dark reputation that comes with being Lucifer's son while trying to prove he's not all bad. Maybe he forms an unlikely alliance with some angels who initially distrust him but later see his good side.
One idea could be Percy having to prove himself in the Underworld. Since he's the son of Tartarus, he might face unique challenges from the other denizens who fear or distrust him. Maybe he has to compete in some sort of underworldly tournament to gain respect.
A great plot idea would be Percy getting trapped in one of Daedalus' old mazes. He has to use his wits and the skills he's learned as a demigod to find his way out. Along the way, he encounters old traps and puzzles set by Daedalus himself. This could also be a chance for Percy to meet the spirit of Daedalus within the maze and learn some valuable lessons from him. Or perhaps Percy has to team up with other descendants of Daedalus to solve a mystery that has been plaguing their family for generations.