Perhaps a fanfiction where Naruto has a descendant in the future who ends up in Percy Jackson's world. This descendant has some of Kaguya's powers that were passed down through the generations. The story could revolve around how this new character tries to hide their powers at first but then has to use them to fight against the Titans or other threats in Percy Jackson's world, all while trying to find a way back to their own world.
Maybe in the fanfiction, the Gods decide to test Naruto and Percy Jackson by pitting them against each other in a series of trials. This could explore how their different backgrounds and abilities influence their performance in the trials.
Another possibility is a story where Percy Jackson finds himself in the Naruto universe and is taken in by Hestia, who has somehow also made her way there. Hestia could act as a guide or protector for Percy while he tries to figure out how to get back to his own world. Along the way, he meets Naruto and they learn from each other's skills and cultures.
One idea could be a crossover where Naruto's world is somehow connected to Percy Jackson's, and Gaea's influence seeps into both. For example, Gaea could manipulate the natural elements in Naruto's world, like the forests and mountains, similar to how she does in Percy Jackson's world. And Naruto, with his ninja skills, teams up with Percy to fight against Gaea's chaos.
In this fanfiction, imagine if Percy Jackson was transported to the Naruto universe during a battle with the Titans. He could use his demigod abilities to help Naruto and his friends against a new threat that has some connection to the Titans. Maybe the Titans' power is being used to create a super - villain in the Naruto world.
One idea could be a crossover where a character with the Rinnegan from the Naruto universe somehow ends up in the Percy Jackson world. Maybe they use their powers in unique ways, like using the Rinnegan's ability to see chakra as a way to detect the demigods' special powers which could be seen as a form of energy similar to chakra.
One idea could be that Percy finds himself magically transported to Skyrim. He could use his water - based powers in the frozen landscapes, like creating ice bridges over rivers or using water currents to his advantage in battles against the various creatures in Skyrim.
A possible fanfiction could involve a crossover where some of the Avengers are sent to Camp Half - Blood. Imagine Tony Stark trying to figure out how the magic at the camp works while also being highly amused by the whole concept of demigods. Steve Rogers could bond with some of the more heroic demigods over their shared sense of duty. Meanwhile, Percy and his friends have to keep an eye on the Avengers to make sure they don't accidentally disrupt the delicate balance of the camp. And then, they all have to face a threat that targets both the Avengers and the demigods, like a group of villains who want to steal the powers of both.
Perhaps there's a plot where the dinosaurs are being used by an evil force. The evil force has found a way to control the dinosaurs and is using them to attack the demigod camps. Percy and his friends then have to figure out how to break the control and save the day. They might find out that the dinosaurs have a connection to an old Greek god or goddess that they didn't know about before.
One idea could be that Percy Jackson discovers a hidden Cybertronian relic. This relic has the power to control water in a way that even Poseidon's trident can't. The Autobots and Decepticons are both after it. Percy has to team up with the Autobots to keep it out of the Decepticons' hands and also figure out how it relates to his world of Greek gods.
In a fanfiction, perhaps the gods in the Percy Jackson universe are aware of Cthulhu as an ancient and powerful being from another realm. They send Percy on a quest to learn more about Cthulhu's weaknesses in case he ever wakes up fully. Percy teams up with some of his demigod friends and they encounter all sorts of Lovecraftian horrors along the way. They soon realize that Cthulhu's power is far greater than anything they've ever faced and they have to rely on their wits and some newfound magic to survive.