A possible plot for a 'Percy Jackson Secret Power' fanfiction could involve Percy having a secret power of teleportation. But this power is not fully under his control at first. He might accidentally teleport to strange and dangerous places. One time he could end up in the middle of a Titan's lair. As he tries to master this power, he discovers that it has a connection to an ancient prophecy. His friends, like Annabeth, help him figure out how to control it and use it for the greater good.
One idea could be Percy discovers a new power related to time during a quest. For example, he might be able to freeze time briefly to escape a dangerous enemy. Another could be that he travels back in time to change an event in the past that has a major impact on the present in the world of the Gods.
Well, perhaps in the fanfiction, the Power of Dominion gives Percy the ability to enter the dreams of other characters. He could use this to either gather information or to influence their actions in a positive way. For example, he might enter the dreams of a demigod who is on the verge of turning to the dark side and convince them to stay good. Also, he could use the power to create a safe haven for demigods, a place where the power of Dominion shields them from all outside threats.
Well, a cool plot might be that Percy somehow gets connected to an ancient power source that gives him the power to create portals. He could use these portals to quickly travel between different mythological realms, but he also has to be careful not to let the wrong creatures or powers through. Or perhaps he gains the power of elemental manipulation related to water, not just controlling it but also changing its state and properties. For example, he could turn water into ice strong enough to build impenetrable fortresses. And then there's the idea of Percy getting a power that lets him see the true forms of all magical beings, which would be both a blessing and a curse as some forms are too terrifying to behold.
Another possibility is that Percy is recruited by a secret organization that has discovered his demigod powers. They see his potential as a secret agent because of his combat skills, quick thinking, and ability to adapt in dangerous situations. In this fanfiction, he might have to work with other agents who are initially skeptical of his 'weird' powers but soon come to respect and rely on him.
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.
A plot could be that Sally Jackson plants a lemon tree in her garden that turns out to be a gift from a minor goddess. The lemons from this tree have the power to give those who eat them the ability to see through illusions for a short time. Percy uses these lemons to his advantage when he is on a mission to retrieve a powerful artifact that is guarded by a monster that uses illusions to protect it.
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.