Some popular sites for 'Heroes of Olympus' fanfiction are Fanfiction.net and Archive of Our Own (AO3). Fanfiction.net has a large collection with various interpretations of the 'Heroes of Olympus' world. AO3, on the other hand, is known for its wide range of fan - created works and a great tagging system that makes it easy to find specific types of 'Heroes of Olympus' fanfiction.
Well, Tumblr is also a good source. There are many blogs dedicated to 'The Heroes of Olympus' where fans share their fanfiction or link to other great works. Additionally, some official Percy Jackson and related series forums might have fanfiction sections. You can interact with other fans there and discover some really unique takes on the story.
First, you need to be very familiar with the 'Heroes of Olympus' series. Know the characters, their personalities, and the world they live in. Then, come up with an interesting concept. It could be a new adventure for the heroes, or a different take on an existing event in the series.
One idea could be exploring the backstories of minor characters in more depth. For example, you could write about the early life of a demigod who was only briefly mentioned in the original series. Another idea is to create alternate endings to the main story arcs, like what if the heroes had made different choices during a crucial battle? You could also focus on the relationships between the characters in a different light, perhaps showing a friendship that was hinted at but not fully developed.
A lesser - known but really interesting fanfiction is 'Annabeth's Quest for Wisdom'. This story follows Annabeth as she goes on a solo quest to gain more knowledge and wisdom. It shows a different side of her character, her determination and her thirst for knowledge in a very engaging way.
Well, a great 'Heroes of Olympus fanfiction' might be one that delves into the backstories of the minor characters. Say, a story about how the satyrs came to be part of the Camp Half - Blood. Or it could be a romantic fanfiction that pairs characters in unexpected ways, like Piper and Frank. Some fanfictions also take the existing plot and give it a darker or more comical spin. For instance, making the quests more dangerous or turning the serious situations into humorous ones.
Naruto is a must - have main character. He's the one who would likely drive the story forward with his determination and unique abilities. Then there could be characters like Hercules from the Olympus side. He and Naruto could have an interesting dynamic, maybe starting as opponents and then becoming friends. And Sakura could also be a main character, representing the medical ninja skills in this strange crossover world.
One highly regarded fanfiction is 'The Lost Hero's Redemption'. It delves deeper into the characters' emotions and backstories, adding new layers to the existing narrative. Another good one is 'A New Quest for the Heroes' which takes the heroes on an exciting new adventure that still feels true to the original series. And 'The Olympus Reborn' is also popular as it presents an interesting alternate universe scenario for the characters.
Some dedicated Percy Jackson or 'The Heroes of Olympus' fan forums might also be a good place to look for fanfiction. For example, the Percy Jackson Wiki's forum may have links or discussions about relevant fanfiction.
Another interesting fanfiction concept could be a tournament - like event where characters from the Kane Chronicles and Heroes of Olympus compete against each other in various challenges. However, they soon discover that the tournament is a ruse by a villain who wants to steal their powers. This would force them to put aside their competitiveness and join forces to defeat the real enemy.