Perhaps in the fanfiction, Reyna is having trouble with some of the new demigods at Camp Jupiter and Percy comes to help her train them. As they work together, they discover a new side of each other and a budding romance might start to form. Reyna could learn from Percy's more laid - back approach to leadership while Percy could learn discipline from Reyna.
A really interesting plot could be set in a future where Percy and Reyna are ambassadors between Camp Half - Blood and Camp Jupiter. They are sent on a diplomatic mission to a third, unknown camp of demigods. On this journey, they encounter old enemies who have formed an alliance against the two main camps. Percy and Reyna must rely on their skills and their growing bond to not only survive but also to broker peace among all the camps.
One idea could be that Percy and Reyna team up to go on a quest to find a lost magical artifact that has the power to restore a dying realm. They face various mythical creatures along the way and start to understand each other's strengths and weaknesses better.
One idea could be Percy and Reyna teaming up for a special quest that takes them to a mysterious and dangerous new realm. They have to rely on each other's skills, Percy's water powers and Reyna's leadership and combat abilities, to survive and complete their mission.
One idea could be that Percy is under a spell or some kind of mind control when he kidnaps Reyna. Maybe a new villain has emerged and is using Percy as a tool. In the fanfiction, Percy might be fighting against this internal force while Reyna is trying to figure out how to break the spell on him.
One idea could be a story where Percy and Reyna have to mentor a group of young demigods. They teach the young ones about their powers, how to fight, and also about the importance of loyalty and friendship. It would show their leadership skills and their bond as they work together towards a common goal.
One interesting Percy Jackson Reyna fanfiction could be where they team up to face a new and powerful monster that the Camp Half - Blood and Camp Jupiter haven't encountered before. It might involve a lot of action scenes and strategic planning between the two.
One plot idea could be Percy having to team up with Hera to rescue a group of demigods who have been captured by an ancient monster. Hera, despite her usual aloofness, realizes she needs Percy's unique skills.
One possible plot could be that Percy is being controlled by some dark force. Maybe a new evil god or an ancient curse. This force makes him kidnap Reyna because she has some important knowledge or power that the dark side wants. For example, she might know the location of a powerful weapon that could tip the balance in a coming war between the gods and the titans' remnants. Percy, against his will, takes Reyna to a secret location. Reyna, being a strong and resourceful character, tries to figure out a way to break Percy out of the control while also dealing with the situation at hand.
Perhaps a fanfiction where Percy and Thalia are transported to an alternate dimension. In this new world, they have to figure out how to get back while also dealing with different versions of their friends and enemies. Thalia might have to face an alternate version of herself who has turned evil, and Percy could be the one to help her see the light again. It would be full of action, drama, and self - discovery.
A plot could involve Hera taking Percy on a journey through the past to show him the origins of the gods' power and how it relates to the current problems in the demigod world. This would give Percy a new perspective and knowledge that he can use to save the day. Or perhaps Percy accidentally stumbles upon a secret of Hera's that she's been hiding for centuries, and she has to enlist his help to keep it safe, all while other gods are trying to uncover it too.
Another plot idea could be that Percy discovers a hidden underwater civilization that is not related to Poseidon. This civilization has its own set of rules and powers. Percy has to navigate through their complex society and politics while also trying to convince them to help the demigods in a coming war against an ancient evil that is rising again. The underwater civilization could have unique magic and technology that the demigods have never seen before.
One idea could be that Percy has to face a new threat from Medusa's long - lost sister who has even more powerful petrifying abilities. He has to use his skills and some newfound knowledge about the Gorgon lineage to defeat her.