One idea could be that Percy, raised by animals, has a unique understanding of nature and can communicate with them in a special way. This could lead to him using animals to gather information or as allies in battles against monsters. For example, birds could be his scouts, and larger animals like bears could be his bodyguards.
One plot idea could be Percy learning advanced combat skills from Chiron at a very young age. Since Chiron is a great teacher, Percy could become an even more formidable hero earlier. Another could be Percy having a closer bond with the centaur community because of Chiron. He might be involved in their internal affairs and help resolve conflicts among them.
Well, perhaps Percy is raised by a group of monsters who are actually being controlled by an even more powerful and malevolent force. Percy then has to figure out how to break the control over the monsters that raised him and turn them into allies. He could start having strange dreams or visions that give him clues about his true heritage and his purpose in this situation. And as he grows up, he starts to notice differences between himself and the monsters, which makes him question everything he's been taught.
One idea could be that Percy is paralyzed during a battle with a new and powerful monster. His friends then have to find a way to heal him while also protecting him from further attacks. Maybe they seek the help of a god who is known for healing but has a difficult task for them in return.
A plot might involve Percy being experimented on by a rogue group of demigods or even a minor god. As a result, he becomes emotionless. His lack of emotions could lead to some really strange situations. For instance, he doesn't show any joy when reuniting with his mother or any sadness when his friends are in danger. His friends initially think he's been replaced by an impostor. But as they figure out what happened, they have to find a way to reverse the experiment. This could involve going on a quest to find a rare ingredient or artifact that can restore his emotions.
A really interesting plot idea could be that the blessing by the Styx actually attracts unwanted attention from the gods. Some gods might be jealous of Percy's new - found power and try to undermine him. He then has to navigate the tricky politics among the gods while also dealing with his own new abilities. Maybe there's a prophecy that's related to his Styx - blessed state and he has to fulfill it, but there are many obstacles in his way, both from the mortal and divine realms.
One idea could be Percy exploring his new powers related to Oceanus. Since Oceanus is a primordial god of the ocean, Percy might have an even deeper connection to the sea and be able to control more extreme oceanic phenomena like underwater volcanoes. Another plot could involve Percy facing conflict within the demigod community as his new heritage changes the power dynamics. Some might fear his increased power, while others might want to use him for their own gains.
One idea could be Percy being forced into this role and having to secretly undermine Kronos' plans from within. Maybe he uses his water powers in unexpected ways to disrupt Kronos' dark magic. Another plot could involve Percy trying to convert some of Kronos' followers to his side, using his charm and heroic nature.
One idea could be Percy discovers a long - lost Hephaestus - made weapon that has special powers. It could be a sword that can cut through any material, but it has a mind of its own and Percy has to figure out how to control it while also dealing with other monsters that are after the weapon.
A possible plot could involve Percy being adopted by Hera and suddenly having access to new powers or abilities that come with being associated with her. But these powers come with a price. He has to perform certain tasks for Hera. Along the way, he meets other characters from Greek mythology that he wouldn't have interacted with otherwise, like some of Hera's more loyal servants or creatures. This could lead to all sorts of adventures and challenges as Percy tries to balance his old life and his new one under Hera's wing.
A possible plot could involve Percy being raised by Poseidon in a hidden underwater realm. He would be trained in the ways of the sea gods from a young age. This could include learning to communicate with all sea creatures, not just the ones in Greek mythology. He might have to face challenges like underwater mazes or taming a powerful sea monster to prove his worth as Poseidon's son. As he grows, he could start to feel a longing for the surface world and the mortals there, leading to a conflict between his loyalty to his father and his curiosity about the world above.