One plot idea could be Percy going on a quest to find a lost artifact that was once in the possession of his father Poseidon. This could lead him to encounter new mythical creatures and face challenges that test his powers in new ways. Another idea is Percy having to deal with the politics among the Big Three's children, where he has to make alliances and navigate through rivalries. Also, a plot where Percy discovers a hidden power within himself that is related to his heritage as the son of a Big Three god and has to learn to control it while also using it to save the world from a new threat.
A great plot could be Percy getting transported to a different realm where the rules of the gods are different. In this realm, he has to find a way back home while also being hunted by a powerful enemy. Since he's the son of the Big Three, he might attract both allies and foes. Or perhaps a story where Percy has to mentor a new demigod who is also a child of one of the Big Three, and they have to learn from each other. Maybe Percy's relationship with his father Poseidon is put to the test when Poseidon asks him to do something that goes against Percy's moral code.
Well, a really cool plot for 'Percy Jackson Son of the Big Three Fanfiction' might be that Percy is sent on a quest where the rules of the demigod world are all messed up. For example, the Oracle gives him a riddle that seems impossible to solve at first. He also could find himself in a situation where he has to choose between saving his friends or fulfilling a prophecy that could save the entire demigod community. He might also have to deal with some internal conflict, like whether or not he should embrace more of his godly side which could potentially make him more powerful but also more distant from his human friends.
A great plot idea could be Percy having to deal with the jealousy of other demigods because of his special status as the 'brother' of the Big Three. This could lead to some tense relationships and even battles within Camp Half - Blood. Or perhaps Percy is forced to make a difficult choice between loyalty to his mortal friends and family and the demands that come with his connection to the Big Three. Maybe there's a story where Percy uncovers a secret power that only he, as related to the Big Three, can access, but it comes with a great cost.
One idea could be Percy going on a quest that was pre - ordained by the Fates. He discovers that his every move is part of a larger plan they have for the demigod world. For example, he might be sent to retrieve an ancient artifact that holds the key to maintaining the balance between the gods and the Titans, and along the way, he has to face challenges that test his loyalty to the Fates' plan.
Well, a great plot for Percy son of Neptune fanfiction could involve Percy getting lost in a time - warp within the ocean. He could end up in an era where Neptune was just starting to gain his powers. This would force Percy to interact with a younger version of his father and also deal with the different rules and threats that existed back then. Additionally, Percy could find a way to bring some knowledge from that time to his present to help in a current conflict. Also, Percy might have to team up with some primitive sea creatures who have their own unique abilities and motives.
One idea could be Percy having to prove himself to Zeus. Since he's his son in this fanfiction, Zeus might be overly critical. Percy could go on a quest to retrieve a powerful artifact that was once Zeus's but was lost. Another plot could involve Percy's relationships with other demigods changing. They might be jealous or in awe of his new status as Zeus's son.
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.
One idea could be Percy going on a quest to find a lost artifact of Athena that has the power to restore balance in the world of the gods. Another could be Percy having to face off against a powerful enemy who is specifically targeting him because of his relation to Athena. Maybe he discovers some long - lost siblings also sired by Athena during his adventures.