Well, in some fanfiction, a great plotline is Percy's struggle with his identity as the 'Son of Gaia'. He might be conflicted between his loyalty to his friends and his new - found connection to Gaia. There could be a story where he tries to find a way to redeem Gaia instead of just fighting her. This could involve him seeking ancient knowledge or artifacts. Also, there could be a plot where Percy has to deal with the jealousy and mistrust of other demigods who see him as a potential threat because of his relation to Gaia.
One interesting plotline could be Percy having to face off against new and powerful monsters sent by Gaia. Maybe he discovers some hidden powers within himself to combat them. Another could be Percy forming an unexpected alliance with a group of demigods who were once his enemies but are now united against a greater threat from Gaia. And he might also have to journey to some long - forgotten places related to Gaia to stop her evil plans.
One idea could be Percy having to deal with the conflicting powers within him from being the son of Gaia and Ouranos. Maybe he discovers a hidden realm that only he can access due to his unique parentage.
One interesting plot idea could be Percy having to deal with the conflicting natures of his 'parents'. Since Gaia represents the earth and Poseidon the sea, he might struggle with controlling both earth - related and sea - related powers. For example, when he's near a beach, he could accidentally cause small earthquakes or make strange things happen to the sea life. Another plot could involve Percy facing a threat that only his unique dual - heritage can defeat. Maybe an ancient evil that is both of the land and the sea, and Percy has to figure out how to combine his powers in a new way to stop it.
Another plotline might be Percy struggling with the expectations that come with being the 'son of fate'. He could be constantly under pressure from the gods or other powerful beings, and he has to find a way to balance his own desires and the greater good. For example, he might be forced to make difficult choices between saving his friends and fulfilling his fated duties, which would add a great deal of internal conflict to the story.
A possible plotline is Percy teaming up with the descendants of Daedalus. Together, they could work on a project to create a powerful defense for Camp Half - Blood. They might face opposition from other characters who are suspicious of Daedalus' legacy, thinking that his creations could be too dangerous. Percy would then have to convince them that the benefits outweigh the risks.
A possible plotline is Percy's struggle to control his chaotic powers. Since Chaos is such a powerful and unpredictable force, Percy may have to learn how to harness his abilities without losing himself. He could go on a quest to find a way to balance his powers, and during this journey, he discovers more about the true nature of Chaos and his place in this new world.
One interesting plotline could be Percy's struggle to balance his new identity as the son of Thetis with his existing loyalties in the Camp Half - Blood world. He might face challenges from his friends who are suspicious of Thetis' motives.
Well, in some fanfictions, Percy as the son of Hermes might get involved in a race against time. For example, he has to stop a group of rogue demigods who are misusing Hermes' speed powers. This could involve him using his wits and new - found abilities as the son of Hermes, like being able to move through shadows or having enhanced communication skills with other beings. He could also form an unlikely alliance with some monsters who are also against the rogues.
One interesting plotline could be Percy's struggle with the chaotic nature of being the 'Son of Eris'. He might constantly find himself in the middle of conflicts that are not his own making, like battles between different groups in the demigod world. His powers could be a mix of his normal Percy abilities and some new chaotic powers from Eris, which would make for some cool action scenes as he tries to control them.
One interesting plotline could be Percy's struggle with his new identity as the 'Son of the Devil'. He might have to face internal conflicts about his nature. For example, he could be torn between his heroic instincts and the dark powers he may inherit.
One interesting plotline could be Percy having to team up with Cerberus in some way. Maybe there's a threat to the Underworld that only they can stop together. Another could be Percy exploring his new 'son of Cerberus' identity and how it affects his relationships with his friends at Camp Half - Blood. For example, some might be scared or distrustful of him at first.