A plot could involve Percy discovering a hidden power within him that is related to Pontus. Maybe he has the ability to control a special type of sea creature that was thought to be extinct. As he tries to master this power, he could face opposition from those who fear his new - found strength. He might also meet other demigods who are either helpful or hindering his journey of self - discovery.
One idea could be Percy discovering new powers related to being the son of Pontus. For example, he might be able to control underwater currents in ways he couldn't before. Another plot could involve him having to face a new type of sea monster that is specifically drawn to his Pontus heritage. He could also go on a quest to find an ancient artifact related to Pontus that has the power to either save or destroy the underwater world.
The plot could involve Percy's journey to discover the true meaning of being the son of Gaea and Pontus. He could be on a quest to find out more about his parents' realms and how they interact with the world of the demigods. Along the way, he may encounter mythical creatures that are related to Gaea and Pontus, and he has to either fight them or make peace with them. There could also be a sub - plot about Percy's relationships with his friends at Camp Half - Blood, as they struggle to accept this new side of him.
Well, it could be about Percy having to deal with the powers and heritage that come with being the adopted son of Pontus. Maybe he discovers new underwater abilities that are different from his Poseidon - given powers. He might also have to face enemies who are after the secrets Pontus has.
Perhaps Percy discovers a prophecy related to his birth. It could state that he is the key to either saving or destroying the world. This would create a lot of internal conflict for him. On one hand, he has his friends and the people he cares about in the mortal world. On the other hand, his powers and his role according to the prophecy could force him to make some very difficult choices.
One common theme is identity. Since Percy has a different parentage than in the original stories, he often has to figure out who he really is. Another theme is power. Discovering his powers as the son of Pontus and Thalassa and learning to control them is often explored.
His fellow demigods could be potential allies. They might understand his struggles and be willing to fight alongside him. For example, a demigod with water - based powers could complement Percy's abilities. Also, some sea nymphs who have a connection to Pontus might offer their help. They could provide valuable information about the underwater world and its secrets.
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 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.
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.