Maybe there's a place in the fanfiction world that has been dried up, like an old, forgotten lake that was once a powerful place for the gods. Percy finds it and decides to 'just add water' to it. As he does, it resurrects an entire civilization of water - based creatures that were thought to be extinct. These creatures have their own culture and rules, and Percy has to navigate between their world and the world of the demigods, trying to keep the peace and also find a way to use their ancient knowledge to stop a new threat to Camp Half - Blood.
Water can be unique as it could have different properties in the fanfiction. For example, it might be able to heal any wound if it's from a certain magical source. Percy could discover this water and use it to save his friends. It would be a game - changer in battles and conflicts.
Well, it could be about Percy discovering new powers over water. Maybe he can control not just regular water but also things like water in plants or even in the clouds. He could use these new powers to defeat some really powerful ancient monsters that are immune to normal demigod attacks.
A plot could involve Percy being sent to Forks on a quest. He discovers that there's a powerful artifact hidden in the area that could cause chaos if it falls into the wrong hands. The vampires and werewolves in Forks are also after this artifact for their own reasons. Percy has to navigate the complex relationships between these two groups while also trying to keep his true identity as a demigod a secret. Along the way, he forms an unlikely friendship with Jacob, who helps him understand the ways of the werewolves.
One possible plot could be Percy arriving in the DxD world and being mistaken for a new, extremely powerful devil. He then has to navigate the complex politics of the devils while also trying to find a way back home. Along the way, he uses his demigod powers in unique ways against the various threats in the DxD universe.
Maybe in the fanfiction, the zoo is a place where the gods have hidden some of their lost magical artifacts. Percy, being the son of Poseidon, senses a strange water - based magic near the aquarium section. He starts to investigate with Annabeth. Along the way, they face challenges from zoo security (who are unknowingly being influenced by a minor god who doesn't want the artifacts found) and various magical traps set around the exhibits.
A plot could involve a new character who is jealous of the mermaids' abilities in 'H2O: Just Add Water'. This character kidnaps one of them to try and take their powers for themselves. The kidnapped mermaid has to figure out how to escape while her friends search for her. They could face many obstacles like false leads and traps set by the kidnapper. In the end, they would likely use their friendship and unique skills to overcome the situation.
One possible plot could be that the Greek gods, noticing the powerful threats the Avengers face, send Percy Jackson and his friends to help. Percy could use his water powers to assist in putting out fires during a battle like the one in New York. Meanwhile, Thor could be intrigued by Percy's connection to Poseidon and they could exchange stories about their godly fathers.
A great plot could involve a prophecy in both the Naruto and Percy Jackson worlds. The prophecy states that only by combining the powers of the ninja and the demigod can a great evil be defeated. Naruto and Percy are chosen to fulfill this prophecy. Along the way, they face challenges like trying to understand each other's cultures. Naruto has to get used to the Greek pantheon, and Percy has to learn about chakra. They also have to deal with their own insecurities. For Naruto, it could be his fear of not being strong enough without the Nine - Tails' power, and for Percy, it could be his fear of losing his friends in the battle.
Here's a more complex plot. There could be a new threat in the demigod world that can only be defeated if the demigods master a new skill, which is figure skating. Percy, along with some of his friends like Annabeth, are chosen to learn figure skating. They have to overcome their initial reluctance and learn the art of figure skating, all while dealing with the normal demigod problems like monster attacks and the politics at Camp Half - Blood. As they progress in their skating skills, they also discover new powers related to the ice and eventually use their figure skating skills to defeat the new threat.
Well, maybe the popularmmos characters accidentally stumble into Camp Half - Blood. Percy and his friends are initially suspicious but then realize they can use the unique skills of the popularmmos crew. Together, they embark on a quest to retrieve a magical item that has been stolen and is now hidden in a strange digital - mythological hybrid realm.