One possible plot could be Percy going on a solo quest specifically designed to help him master his powers. He might face challenges that force him to use his water - based powers in new and extreme ways, like having to freeze an entire lake to stop a monster from escaping. Along the way, he could meet a new mentor, perhaps an ancient water spirit, who teaches him secrets about his abilities that he never knew before.
Maybe in the fanfiction, Percy's powers start to go out of control. He has to figure out how to master them to avoid hurting his friends. He could be in a situation where his emotions are directly linked to his power surges. So, he goes on a journey of self - discovery, learning to control his emotions which in turn helps him master his powers. For example, when he gets angry, his powers go wild, but as he learns to stay calm, he can direct his powers more precisely.
It could be a rogue demigod who is jealous of Percy's powers and wants to stop him from mastering them. This demigod might have some dark powers of their own and would constantly set up traps and challenges for Percy. For example, they could use illusions to make Percy doubt his own powers and abilities.
One possibility is that Percy trains his powers with the help of his friends. They could create special scenarios or obstacles for him to overcome, which in turn helps him to develop his powers further. His powers could also start to evolve in unexpected ways during this training process.
In a more complex plot, Percy could be forced into a boxing match by a powerful enemy who wants to humiliate him. But Percy turns it into an opportunity to unite the demigods. He uses the boxing ring as a platform to give inspiring speeches between rounds. And as the matches progress, he gradually gains the respect of both his allies and former foes through his tenacity and skill in the ring.
He could have the power to freeze water instantly. Since he has a connection to water already as a son of Poseidon, this would be an extension of that. He might also be able to create ice storms and blizzards at will.
One possible plot could be that the entire Greek pantheon is thrown into chaos. Percy might be seen as a huge threat, and other gods and goddesses would either try to hunt him down or form alliances with him out of fear or a desire for power. Demigods would be forced to take sides, leading to massive battles among them.
Well, in such a fanfic, perhaps Percy ends up in a new camp or place full of demigods he doesn't know. He has to prove himself without his mom's support. He could befriend some unlikely characters who help him understand more about his mother's disappearance. And in the end, he might find that his mom left to protect him from a greater threat that he now has to face on his own.
It's possible that his powers could even be enhanced in some ways. Losing an eye could make him more in tune with his other senses, and this could translate to his powers. For instance, his ability to sense danger through water vibrations could become sharper as he has to rely more on it. His powers might also develop in new directions. Maybe he could start to use water to create illusions to compensate for his lost vision in battle, like using water to project false images of himself to confuse his enemies.
Well, he might disappear because of a powerful curse from an ancient enemy. Maybe he gets trapped in a different dimension. When he returns, he could have new powers or knowledge. For example, he might have learned some secret magic from the other dimension that helps him defeat a new threat in the Percy Jackson world.
One possible plot could be that Percy is tricked into a deadly situation by a new villain who has the power to manipulate the elements. Percy is killed in a massive explosion. But his love for Annabeth and his loyalty to his friends are so strong that his soul doesn't pass on. Annabeth, using her intelligence and her knowledge of ancient magic, figures out a way to reach Percy in the in - between world. With the help of some friendly spirits, she brings Percy back to life, and they then set out to defeat the villain who caused his death.
Another plot could be that there is a rift between the worlds of angels and demigods that is causing chaos. Archangel Gabriel is tasked with closing the rift, but he needs Percy's help as Percy has a unique connection to the elements. Along the way, they face challenges from both sides who don't want the rift to be closed, and they have to fight against all odds to restore order.