One great idea could be a story where Percy Jackson's world is in danger and Captain Marvel is somehow drawn into it. Maybe a powerful ancient Greek monster has powers that start to affect other dimensions, and Captain Marvel comes to help. She could use her super strength and energy blasts to fight alongside Percy and his friends against the monster. Percy, with his control over water, could also be useful in a fight, like creating a giant wave to distract the enemy while Captain Marvel attacks.
Another crossover idea is that Captain Marvel is on a mission in space and stumbles upon a lost Greek island that is filled with Percy Jackson - like characters. She has to figure out how to work with them to solve a mystery on the island. The demigods are initially wary of her, but they soon realize her powers can be of great help. For example, Captain Marvel could fly up to get a better view of the island's layout while the demigods search the ground for clues.
A really interesting crossover could be where the gods in Percy Jackson's world notice Captain Marvel's power and try to either recruit her or stop her because they see her as a threat to their power. This could lead to a conflict where Percy has to choose sides. He might see the value in Captain Marvel's more modern sense of justice and decide to side with her against the sometimes - tyrannical gods.
A crossover with Doctor Strange could be really cool. Maybe they have to deal with a magical threat that is spreading across different dimensions. Captain Marvel's strength and Doctor Strange's magic would create an interesting dynamic as they try to figure out how to stop it.
A fun crossover could involve the Justice League somehow getting trapped in the Camp Half - Blood world. They have to adapt to the rules and challenges of the demigod world, like the monster attacks and the training regimens. Meanwhile, Percy and his friends have to deal with the presence of these super - powered heroes and figure out how to get them back to their own universe. It could lead to some interesting interactions, like Wonder Woman teaching the demigods some combat techniques from her own world, and Flash trying to outrun some of the mythical creatures.
One idea could be that Nick Fury discovers Percy Jackson's abilities and tries to recruit him for SHIELD. He sees Percy as a valuable asset with his demigod powers. Another could be Percy getting caught in a situation where he has to team up with Fury to stop a common enemy that is a threat to both the demigod world and the world of superheroes. Maybe an ancient monster that has been awakened by some sort of scientific experiment gone wrong and Fury needs Percy's knowledge of mythology to defeat it.
Another interesting concept is a story where Percy Jackson is somehow transported to the Marvel universe. He could use his water - controlling powers in unique ways there. Maybe he'd join forces with Namor, the Sub - Mariner, and they'd have an underwater adventure together, facing off against some underwater threat that only their combined powers could handle.
One idea could be a quest where Magnus and Percy have to team up to retrieve a powerful artifact that is causing chaos in both their worlds. Maybe it's an ancient Norse and Greek combined relic that only their combined skills can handle.
In the fanfiction, Percy might face off against other mythological creatures while at sea. Maybe he has to deal with sea serpents that are causing trouble for his ship. His sword - fighting skills, along with his powers, would come in handy. He could also form alliances with other demigods or mythical beings who have an interest in the high seas.
A very creative idea is the use of prophecies. In the Percy Jackson series, prophecies play a big role. Some fanfictions incorporate this into the Marvel crossover. There could be a prophecy that predicts the coming together of the demigods and the superheroes to save both universes from a great threat. This forces the characters from both worlds to work together, even if they don't initially trust each other. It adds an element of mystery and fate to the story, making it more engaging.
One idea could be a crossover with the Harry Potter universe. Percy could visit Hogwarts and have to deal with both magical and mythological threats. Maybe he'd team up with Harry to defeat a common enemy that combines dark magic and ancient Greek monsters.
I really like 'Percy in the Marvel Universe'. In this fanfiction, Percy gets transported to the Marvel universe. He has to figure out how to get back home while also dealing with all the superheroes and villains there. It shows his character development as he tries to adapt to this new and very different world. The story also has some interesting pair - ups, like Percy and Spider - Man becoming friends and having adventures together.
Another idea is that Sophie Foster from KotLC travels to the Percy Jackson universe. She could be mistaken for a demigod at first. She would have to learn about the Greek gods and monsters. Her telepathic abilities would be really useful in the Percy Jackson world. For example, she could communicate with some of the monsters to find out their plans. And Percy and his friends would help her understand this new and dangerous world.