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.
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.
Miscommunication also plays a big role. In fanfiction, they might not fully understand each other's motives or goals. Jon may say or do something that Dany misinterprets as a threat to her rule, and she may respond in a way that further aggravates the situation.
A very common plot device is the exploration of their pasts. Fanfic authors might dig into Nagato's past and find some hidden link to Naruto's past. For instance, they could discover that their families were somehow connected long ago. This discovery then forms the basis of their relationship in the fanfiction. It gives a sense of destiny and inevitability to their connection, as if they were always meant to cross paths and influence each other.
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 plot device is the 'damsel in distress' trope, where Zoe is in immediate danger and Percy swoops in to save her. This could be from a monster attack or a magical trap. Another is the 'power - up' device, where Percy discovers a new aspect of his powers just in time to rescue Zoe.
One common plot device is the protagonist having knowledge from their past life. For example, they might know about future events in the Percy Jackson world and use that to their advantage. Another is forming unexpected alliances. Since they are reincarnated, they could team up with characters who were previously enemies. Also, there's often the struggle to fit into the existing world while being different because of their reincarnation.
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.
A common plot device is the misinformation or false memories within the story. For instance, Sakura might have been raised believing one thing about her father, but then through a series of events in the fanfiction, she discovers that Madara is her real father. Another device could be the use of a special bloodline or power that only makes sense if Madara is her father. This power then becomes a central part of the plot as Sakura tries to master it and understand her true identity. Also, the idea of a fated encounter between Madara and Sakura's mother, which was kept secret for some reason, is often used to drive the story forward.
One common plot device is the discovery of a hidden letter or prophecy that reveals the relationship. Another is a magical bond that starts to surface between Snape and Voldemort as the story progresses. Also, there might be a plot where Snape has to struggle with his new - found identity and his loyalty to Dumbledore.