A great Percy Jackson fanfic idea is crossovers. Combining the Percy Jackson universe with other popular franchises like Harry Potter. Imagine Percy going to Hogwarts and interacting with wizards. It would be really interesting to see how his powers compare to magic. Also, fanfics could be about Percy having a different parentage. Maybe instead of Poseidon, he was the son of a different god, which would completely change his story and character.
Some fanfic ideas involve time - travel. For instance, Percy going back in time to meet his parents when they were younger or to prevent some of the disasters that happened in the past. There are also fanfics that center around new prophecies. The author creates a new prophecy that the demigods have to deal with, which can lead to all kinds of new storylines and character developments. Fanfics might also explore the idea of the demigods going to different mythologies' realms, not just the Greek ones.
One popular idea is exploring different relationships between the characters. For example, a fanfic could focus on the friendship between Percy and Grover in more depth, showing their adventures outside of the main story. Another idea is alternate universes. This could be where the Greek gods have different roles or the demigods have different powers. Some fanfics also like to expand on the backstories of minor characters, like giving more details about Nico's time before he joined the main group.
In a fanfic, perhaps Percy and his friends accidentally stumble upon Medusa's lair while on a quest. But instead of immediately attacking, Medusa offers them a deal. She says she will give them a valuable clue to complete their quest if they help her get revenge on one of the minor gods who wronged her in the past. Percy and his friends then have to decide whether to trust Medusa or not.
A positive fanfic idea could be Percy mentoring new demigods at Camp Half - Blood. This would show his growth as a character and his ability to pass on his knowledge and skills. Also, a fanfic about Percy and his friends exploring a lost city full of ancient magic and mystery would be really exciting. It would stay true to the adventurous spirit of the original series without any inappropriate content.
A 'Percy Jackson crossovers fanfiction' could involve a crossover with the Star Wars universe. Demigods in a galaxy far, far away would be a wild concept. They might have to face the Sith or team up with the Jedi. Also, a crossover with the Lord of the Rings. Demigods in Middle - earth could bring a whole new dynamic to the fight against Sauron. Maybe they could use their powers to help Frodo on his journey.
One popular theme is alternate universes. Fans like to imagine what would happen if certain events in the original story were different. Another is the expansion of character backstories. For example, exploring more about a minor character's past. Friendship among the demigods is also a big theme, showing how they support each other through various challenges.
One popular type is the 'What if' fanfics. For example, 'What if Percy had joined the Titans?' It explores different paths the characters could have taken. Another is the 'Next Generation' fanfic, which focuses on the children of the original characters, like Percy and Annabeth's kids having their own adventures in the demigod world.
There are fanfics that center around new quests for Percy and his friends. These might involve going to unexplored regions in the Percy Jackson world, facing new monsters or gods that were not in the original series. Some fanfic authors also like to bring in elements from other mythologies and blend them with the existing Percy Jackson lore, creating really interesting and unique stories.
One idea could be a fanfic where Sally tells Percy stories about his father from her own perspective before he knew the truth. It would give a deeper look into their relationship and how Sally coped with the knowledge of Poseidon.
Another interesting concept is a crossover of the storylines. The prophecy in Percy Jackson could somehow be related to the events in Undertale. For instance, the hero's journey in both worlds might be intertwined, with Percy and Frisk having to work together to save both their universes from a common threat.
Well, you could have a fanfic where Percy is given a science homework about marine biology, and he uses his knowledge from being the son of Poseidon to write an amazing paper. He might even bring in some sea creatures from the ocean to show as examples, which of course causes chaos in the classroom. Another idea is that the whole demigod gang has to do a group project on mythology, and they each contribute their own unique experiences with the gods and monsters.
In a 'Percy Jackson tattoo fanfic', you could explore the idea of a tattoo artist who is actually a minor god or goddess. The story could follow Percy or another character as they go to get a tattoo from this divine artist. The tattoo could have powers that are both a blessing and a curse, like it gives the wearer enhanced strength but also attracts more monsters. And the process of getting the tattoo could be filled with mythological elements, like the ink being made from the essence of a magical creature.