Obviously, Percy is the central character. As the heir of Kronos, he is the focus of the story. His friends like Annabeth are also important characters. Annabeth often serves as Percy's moral compass, trying to keep him from fully succumbing to the dark influence of his new heritage. Grover might also be there, providing his usual support and comical relief.
Well, 'Percy: Kronos' Legacy' is a popular 'Percy Heir of Kronos' fanfic. It shows Percy dealing with the expectations and curses that come with being the heir. It also has some really cool battle scenes where Percy has to use his new powers in unexpected ways. There's also 'The Heir Unveiled' which explores how the other characters in the Percy Jackson universe react to Percy's new status.
Well, the main antagonists could be a group of rogue demigods who have formed a cult around Kronos. They believe that Percy, as the heir of Kronos, should lead them in overthrowing the current order of the demigod world. But Percy doesn't want any part of it, so they become his enemies. Another possible antagonist could be an ancient being that was once in league with Kronos and now sees Percy as a means to resurrect Kronos or continue his dark legacy. This being would stop at nothing to force Percy to embrace his role as the heir.
Well, for 'percy x kronos fanfic', there are some really creative ones out there. Some focus on a world where Kronos is redeemed in part because of Percy's influence. In these fanfics, the authors often play with the idea of fate and how two such opposing characters could come together. For example, in 'A New Beginning', it shows Percy trying to understand Kronos' past and how that could lead to a different future for them both.
One idea could be Percy having to face moral dilemmas as he discovers more about his connection to Kronos. For example, he might be tempted by the power Kronos once held. Another could be Percy having to deal with the distrust of his friends who fear he'll turn into an heir of Kronos in a bad way. He could also go on a quest to find a way to sever his connection to Kronos if it's a negative one.
In many fanfictions, Percy might use his water powers in a unique way. Maybe he combines his control over water with his sword fighting skills. He could create a giant water vortex to disorient Kronos and then strike with Riptide while Kronos is off - balance.
The character development of Kronos is also important. Fanfic writers often explore his past and what led him to become the villain he is. They might give him more complex motives, like a desire for revenge that goes beyond just power. Also, the relationships between the characters, like Percy's relationship with his friends in the face of Kronos' threat, are key elements. In some fanfics, these relationships are tested and strengthened in different ways.
Another good one is 'Kronos' Plan Unraveled by Percy'. In this fanfic, Percy is super intelligent and manages to outwit Kronos in a very unexpected way. It has a lot of plot twists and turns that keep you on the edge of your seat. The relationship between Percy and Kronos is portrayed in a very unique and engaging way.
Maybe there are some original characters created by the fanfiction author. These characters could have their own unique abilities and backstories. They might be the ones who tip the scales in Percy's favor, for instance, by having a special power that weakens Kronos just before Percy makes the final blow.
Luke could also be a prominent character. Since he has a complex relationship with Kronos in the original story, in fanfiction he could play a role in either helping or hindering fem Percy's efforts against Kronos. Nico di Angelo is another possibility. His powers over the dead could be useful in a fight against Kronos, and he might team up with fem Percy for that reason.