One common plot device is Percy having to prove himself among the Chaos Generals. Since he's new to this chaotic realm, he often has to show his skills and loyalty. Another is the discovery of new powers. Maybe he gets some powers related to chaos that are unique and he has to learn to control them. Also, there could be a rivalry plot where Percy has to face off against another general who doesn't believe he belongs there.
Well, a frequent plot device is Percy's struggle with his identity. He's used to being a certain way in his old world, but in the Chaos Generals' world, he has to redefine himself. There might be a plot where he has to solve a mystery that threatens the chaos realm. It could be something like a strange power outage or a missing artifact. And sometimes, there's a friendship - building plot where Percy forms strong bonds with some of the other generals which helps him in his new role.
Percy is often portrayed as a fish - out - of - water at first. He's in a new and strange world with the Chaos Generals, so he has to learn the ropes quickly. He's also shown as being very determined. No matter the challenges thrown at him, he doesn't give up easily.
Well, often there might be a plot device where Apollo gets jealous easily. So, if Percy shows any attention to other characters, Apollo would react in a possessive way. This could lead to conflicts between Apollo and those other characters. Also, the fanfiction might use the device of Apollo secretly following Percy around to keep tabs on him. He could be using his godly abilities to spy on Percy, which would add an element of mystery and drama to the story.
A common plot device is the influence of dark magic. If Percy is exposed to some form of dark magic, it could slowly corrupt his mind and soul. For instance, a cursed object that he comes into contact with might start to change his personality, making him more selfish and cruel.
Another plot device could be Thalia's submissive behavior in a romantic relationship. Perhaps she falls for someone who has a dominant personality, and her submissiveness in that relationship creates interesting relationship dynamics, like having to compromise more than she's used to.
The theme of transformation is also prevalent. Percy's encounter with Chaos usually changes him in some way, whether it's his personality, his relationships, or his understanding of the world. This transformation can be both positive and negative, and it makes for an interesting exploration of his character as he adapts to these changes.
The theme of chaos vs order is also prevalent. These fanfictions play with the idea of how Percy, who has been used to a world with a certain level of order (despite being a demigod), navigates a world that is dominated by Chaos. It can lead to some interesting internal and external conflicts within the story.
Time - travel or dimension - hopping can be a plot device. It allows Percy to go back in time to fix things in the universe's history or jump to different dimensions to solve problems. Also, the prophecy plot device is often used. There could be a prophecy about Percy's rise and fall as the God of the Universe, which drives the story forward. And then there's the redemption arc of some of his old enemies who now see him as the ultimate power and want to be on his side.
One common plot device is the prophecy. There could be a prophecy about Percy that makes the gods take a special interest in him. Another is the power - up. The gods might bestow Percy with new and extraordinary powers, which then drives the plot as he has to learn to control and use them. Also, the introduction of new mythical creatures that are either sent by the gods or are related to Percy's new - found status among the gods can be a plot device.
One common theme is the disruption of the normal order. For example, in many stories, the gods' rules or the Camp Half - Blood's usual way of life is thrown into chaos, and Percy and Piper have to adapt. Another theme is the growth of their characters. Through facing chaos, they learn more about themselves and become stronger.
One common theme could be the contrast between Percy's more orderly world (if we consider his normal life in his own series) and the chaos he now loves. It might explore how he adapts to this new aspect of his life.