A possible plot for this fanfiction is that Percy's glasses are a gift from an unknown god or goddess. The glasses seem ordinary at first, but as he uses them more, he discovers that they can change his perception of the world. He might be able to see the true forms of monsters even when they are disguised in human form without having to rely on his demigod senses as much. This could lead to some interesting encounters where he's the only one who can see the danger right away.
Perhaps in the fanfiction, Percy's glasses are enchanted. They are the key to unlocking an ancient prophecy. But he doesn't know it at first. As he goes about his normal adventures, he notices strange things happening when he has his glasses on. For instance, certain symbols or messages appear only when he looks through the lenses. He then has to figure out what these messages mean and how they relate to the prophecy, all while dealing with his normal demigod duties like fighting monsters and trying not to get expelled from school.
One idea could be a quest where Percy and Artemis have to team up to rescue a group of demigods captured by a powerful new enemy. Maybe a Titan who has found a way to drain the powers of young demigods. Percy's skills in water manipulation and combat, combined with Artemis's archery and her connection to the moon, would make for an exciting adventure as they face various challenges along the way.
Well, a plot could involve Percy Jackson stumbling upon a hidden cave where cavemen are in a sort of stasis. When they wake up, they mistake Percy for a god because of his powers. Percy then has to teach them about the modern world while also learning about their primitive yet magical ways of life. Maybe there are ancient artifacts in the cave that are related to the Greek gods and Percy has to protect them from being misused.
One plot idea could be that Percy has to face Arachne in a battle of wits rather than just a physical fight. Maybe Arachne weaves illusions within her webs that Percy has to break through to reach her. Another could be a scenario where Arachne tries to use Percy to get revenge on the gods by tricking him into stealing an important artifact from Olympus. A third idea is that Percy and Arachne form an unlikely alliance when a greater threat emerges that endangers both of their existences.
A plot could involve Percy accidentally stumbling into Artemis' territory. At first, Artemis is angry but then realizes Percy has information about a threat to her hunters. So they start an adventure to stop this threat. During the journey, they learn more about each other's worlds and develop a mutual respect. Or maybe there's a spell that makes Artemis lose her powers temporarily and Percy has to protect her while she regains them.
A possible plot is Percy being sent on a mission by the gods to study a strange phenomenon in the ocean that is affecting both the mortal and demigod worlds. He uses his scientific skills, which he has developed over time, to analyze the situation. He might encounter sea monsters that are acting oddly due to this phenomenon and has to figure out how to stop it. Or perhaps Percy is recruited by a secret scientific organization within the demigod world that is trying to find a way to bridge the gap between the magic of the gods and modern - day mortal science. He could bring a unique perspective with his experiences as a demigod.
A really interesting plot could be that Cupid, for some reason, decides to make Percy the ultimate symbol of love in the demigod world. Percy is then thrust into a role he doesn't understand, having to deal with love - sick demigods coming to him for advice. Meanwhile, he has his own relationship problems, like his feelings for Annabeth being complicated by this new status. He has to figure out how to handle Cupid's meddling and restore some normalcy to the love lives of those around him.
One idea could be Percy having to adapt his demigod skills to his new situation in a wheelchair. For example, he might have to figure out new ways to fight monsters. Maybe he uses his wheelchair as a weapon somehow, like ramming into foes or using it to block attacks. Another plot could involve his friends helping him adjust, and together they discover new powers or artifacts that are specifically useful to him in his wheelchair - bound state.
Another plot could involve Percy getting a vision from Athena about a future threat to the demigod world. But the vision is so cryptic that he has to work closely with Athena to decipher it. Along the way, they build an unexpected bond, different from his usual relationships with other gods. Maybe Percy starts to see Athena not just as a powerful deity but as a mentor figure, and Athena starts to respect Percy's tenacity more than she expected.
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 idea could be Percy and his friends getting trapped in a virtual game world that's a twisted version of their own. They have to use their demigod skills to defeat the digital monsters and find a way out.