The allure lies in the fact that Percy already has a very interesting backstory. As the Champion of Poseidon, fanfiction writers can expand on his powers and his place in the mythological world. For instance, he could be sent on quests that are specifically related to Poseidon's domain, like protecting a sacred sea temple from an ancient evil.
One possible plot could be Percy's internal struggle. Since Gaea is often seen as a villain in the Percy Jackson series, Percy would have to come to terms with his dark heritage. He might be shunned by his friends at first. But then, as he discovers that he has the power to control earth and sky elements from his parents, he could use it for good. For example, he could prevent natural disasters that Gaea might have caused in her malevolent state. And he would have to prove to everyone that he is not like his mother, but a hero in his own right.
It could be a powerful demigod who has been corrupted by power. This demigod wants to be the sole champion of the arena and will stop at nothing to defeat Percy.
Well, you could write a fanfiction where Percy Jackson is framed for a crime he didn't commit at Camp Half - Blood. As a champion, he has to prove his innocence while also dealing with the fact that some of his friends start to doubt him. He then embarks on a journey outside the camp, with only a few loyal friends by his side, to find the real culprit and clear his name. This could involve facing various mythological creatures and obstacles along the way.
One of the most intriguing characters is Annabeth. In the context of Percy being the champion of Mars, Annabeth could be in a tough situation. She might be worried about Percy changing because of his new role and she has to figure out how to support him while also dealing with her own feelings. Another interesting character could be Grover. Grover's role as a satyr might bring in some unique elements. He could be the one who discovers some hidden lore about Percy's connection to Mars that no one else knew.
Well, Percy himself is always a memorable character. His courage and quick - thinking in the face of magical challenges make him stand out. Also, any new characters that are created in the fanfiction, like a powerful wizard who mentors Percy in the ways of magic, could be very memorable.
One interesting plot could be Percy having to face a new and powerful magical enemy that is immune to his usual water - based powers. So he has to quickly learn and master new forms of magic to defeat it.
The Furies could also be major antagonists. They are already powerful and feared in the Underworld, and Percy as the Champion of Erebus might be seen as a threat to their authority. They could try to undermine him at every turn, setting up traps and sending various minions after him. Additionally, there could be a new, unknown force emerging from the darkest parts of Erebus that is opposed to Percy's role. This could be a primordial being that has been awakened by Percy's ascension and wants to return the Underworld to a more chaotic and lawless state.
There could be a new Titan that we haven't seen before. This Titan could be more cunning and powerful than the others. Maybe he's been in hiding all this time, waiting for the right moment to emerge and lead the Titans to victory. He could manipulate Percy's friends against him and create all sorts of problems for our hero.
One great Percy Jackson Queen's Champion fanfiction can be found on FanFiction.net. It delves deep into Percy's new role as the Queen's Champion. The story is exciting as it shows Percy using his demigod skills in a different context, facing challenges specific to this new position.