What could be an interesting plot for a Percy Jackson and H2O crossover fanfiction?

One possible plot could be that the characters from H2O, who have the power to transform into mermaids in water, end up in the wizarding world of Harry Potter. They could be mistaken for some kind of new magical creature. The Hogwarts students might be both intrigued and a bit wary of them. Maybe they could help the students in a Triwizard Tournament task that involves water in some way.

Maybe a magical item gets lost that is crucial to both the H2O and Mako Mermaids' worlds. It could be a pearl that has the power to keep the balance of the ocean's magic. A young mermaid from H2O and a young mermaid from Mako accidentally cross paths while looking for it. At first, they are suspicious of each other. But as they search together, they start to understand each other's powers better. The H2O mermaid can freeze water to access hidden caves, while the Mako Mermaid can use her singing to call upon sea creatures to help. Eventually, they find the pearl and in the process, they create a friendship that bridges the gap between their two worlds.

Annabeth from Percy Jackson could be really interesting. She's smart and strategic. In a crossover, she could be the one to figure out how the H2O girls' powers work and how they can be used to everyone's advantage. Also, Cleo from H2O has her own charm. She comes from a different background and her insecurities combined with Annabeth's confidence would make for great character development.

One possible plot could be that the Volturi from Twilight discover the existence of demigods from the Percy Jackson world. They see the demigods as a threat to their vampire supremacy. Percy and his friends have to team up with some of the more friendly vampires, like the Cullens, to fend off the Volturi. This would bring together the magic and powers of both universes in an epic battle.

Well, perhaps there's a villain in the Percy Jackson universe who discovers that the iCarly web show has a huge following and decides to use it as a way to spread chaos. The demigods have to team up with the iCarly crew to stop this. The iCarly gang has to learn about the world of Greek mythology really fast and help the demigods navigate the modern world of technology and media to defeat the villain.

Well, it could start with a magical accident. In the Percy Jackson universe, a spell gone wrong sends Percy, Annabeth, and Grover into the land of Alagaësia from Eragon. There, they discover that the demigod powers Percy has are seen as a strange and new form of magic. Eragon is initially suspicious of them but realizes they can help in his fight against Galbatorix. They combine their skills, Percy's water - controlling powers and sword - fighting skills, along with Annabeth's strategic mind and Grover's nature - sensing abilities, with Eragon's dragon - riding and magic - wielding skills to take on the dark forces.

The plot could involve a powerful magical artifact that has military applications. The NCIS comes across this artifact during an investigation but doesn't understand its true nature. Percy Jackson and his friends, who are on a quest to retrieve the artifact for the demigod world, cross paths with the NCIS. There is a lot of miscommunication at first as the two groups have different goals and ways of operating. But as they realize that they are both facing a common threat from a group of rogue demigods and power - hungry military personnel, they join forces. Percy uses his knowledge of the demigod world and his powers to help the NCIS agents navigate the magical aspects while the agents use their resources and combat training to take on the human threats.

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.

One idea could be that the demigods from Percy Jackson end up in Riverdale due to some sort of magical mishap. Percy could be confused by the strange mortal world of Riverdale, with its own set of secrets and drama. Meanwhile, the Riverdale gang could be in awe of the demigods' powers. For example, Archie might be inspired by Percy's heroism and try to be more like him in facing the town's problems.