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.
A plot idea might involve Percy meeting other children of monsters. They form an unlikely alliance to fight against a common enemy that threatens both the demigods and the monsters. Since he is the son of Medusa, Percy could have a special connection to the world of monsters that other demigods don't. He could use this to broker peace between the two sides in the end.
Perhaps Percy discovers that there is a prophecy about him being the son of Medusa. The prophecy says that he will either bring great destruction or be the key to saving both the mortal and the mythological worlds. As he tries to figure out his role, he faces many challenges and has to make difficult choices along the way.
One idea could be a time - travel plot where Percy goes back in time and meets a younger, different Medusa before she was turned into a monster. Another could be a story where Medusa somehow gets a chance at redemption and Percy has to decide whether to trust her or not. Maybe a plot where they have to team up to defeat a greater evil that threatens both of them.
One idea could be that Percy has to face a new threat from Medusa's long - lost sister who has even more powerful petrifying abilities. He has to use his skills and some newfound knowledge about the Gorgon lineage to defeat her.
In a fanfic, perhaps Percy and his friends accidentally stumble upon Medusa's lair while on a quest. But instead of immediately attacking, Medusa offers them a deal. She says she will give them a valuable clue to complete their quest if they help her get revenge on one of the minor gods who wronged her in the past. Percy and his friends then have to decide whether to trust Medusa or not.
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.
One idea could be Percy's struggle to fit in among the other demigods while having Fenrir as his father. He might have unique powers that make others suspicious. For example, he could have enhanced strength and a connection to wolves that the other demigods don't understand.
Another plot could involve Percy's relationship with his father, Hades. Maybe Hades has some grand plan for Percy that he doesn't fully understand at first. Hades could be trying to use Percy to gain more power in the world of the gods, but Percy resists and has to fight against his father's wishes while also dealing with the internal conflict of not wanting to completely turn his back on his family.
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.