Perhaps there are some traitors from the other side. These characters, seeing Kronos' power and potential for victory, switch sides and help him in the war. They might provide valuable information about the enemy's defenses and plans.
Some of Kronos' minions, like the monsters he commands, could be antagonists. For instance, the dracaenae. They are always eager to prove themselves to Kronos and might see Percy as competition within Kronos' ranks. They could constantly try to undermine Percy's position and cause trouble for him.
The other Titans could be main antagonists. For example, Hyperion who is known for his great strength and his desire for destruction. He might not fully trust Percy and constantly try to undermine him in Kronos' eyes. Another could be Atlas, who is already a major foe in the Percy Jackson series. He might see Percy as a threat to his own plans within Kronos' regime.
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.
John Smith is a well - known author in Kronos science fiction. He has written 'The Kronos Revelation' which is a thrilling story about a secret hidden within the Kronos system. Another is Jane Doe who created 'Kronos: The New Dawn' with her unique vision of the Kronos future.
Annabeth is often a popular character. In fanfiction, she might play a crucial role in helping Percy deal with his complex identity as the son of Kronos. Grover could also be popular as he's Percy's loyal friend and could be there to support Percy through his struggles related to his new - found heritage.
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.
Hesiod was one of the first to mention Kronos in his epic works like 'Theogony'. His accounts were very important in establishing the early understanding of Kronos and the Titans in Greek mythology.
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.