One idea could be that Percy and Leo team up to build a super - cool underwater vehicle using Leo's mechanical skills and Percy's knowledge of the sea. Another could be them going on a quest to find a lost artifact that has powers related to both fire and water. They could face challenges like sea monsters and mechanical traps along the way.
One plot idea could be Percy and Thalia going on a quest together to find a lost artifact that has the power to save their camp from a new threat. Another could be them getting into an argument over how to handle a new demigod at camp, which tests their friendship but ultimately makes it stronger. Maybe they could also travel to a different realm together where they have to rely on each other completely to survive and get back home.
One idea could be that Percy and Jason have to team up to save a group of demigods who are trapped in an ancient, cursed maze. They use their combined powers of water and lightning to break through the various obstacles. Another could be a story where they swap powers for a day and have to deal with the consequences. For example, Percy tries to control lightning but accidentally zaps some of their friends' hair into crazy styles, while Jason struggles to keep the water from going wild when he tries to use Percy's power.
They could get lost in an old, abandoned part of the railway. Thomas might be a bit scared at first, but Percy stays calm. Together, they explore the area, find old railway artifacts, and then figure out a way to get back to their normal tracks. It would be a story of discovery and courage.
One plot idea could be Percy and Annabeth going on a quest that has nothing to do with the main prophecies. They could be exploring an ancient, forgotten land just for the fun of it and to learn more about the world. Along the way, they face challenges that test their friendship like when Percy accidentally angers a local spirit and Annabeth has to use her wits to calm the situation.
Another plot could involve Percy's friends getting accidentally transported to a different realm in the Percy Jackson universe. They have to rely on their friendship and the skills they've learned from Percy to survive and find their way back. For example, they might end up in the Underworld and have to navigate past various challenges without Percy at first.
One idea could be that as a girl, Leo has to face different challenges in leading the team. Maybe she has to deal with more doubts from others at first because she's female. But she overcomes them with her skills and determination.
Perhaps a plot where Leo discovers some new powers or abilities that are related to his pregnancy. It could be something that he has to learn to control quickly. And then there could be a story arc about the team finding a way to ensure a safe delivery for Leo, which might involve seeking out some very rare or magical items.
Maybe in the fanfiction, there is a prophecy that involves Tigerclaw and Leo. They are initially skeptical but as strange events start to unfold around them, they are forced to work together. Along the way, they face many challenges like distrust from their own sides, but their growing friendship helps them overcome all that.
One idea could be Taylor and Leo teaming up to solve a mystery within the lab. Maybe they discover a hidden project that could change the future of the lab rats. Another plot could be a love triangle situation where Taylor has feelings for Leo, but Leo is focused on his friendship with the lab rats and their missions.
One idea could be that Percy is framed for stealing a powerful magical artifact. His friends initially doubt him, but as he tries to prove his innocence, he uncovers a conspiracy within the magical community. For example, a secret group wants to use the situation to gain more power and is setting him up as a scapegoat.