One idea could be Percy having to face an ancient prophecy that only he, as the last of the seven, can fulfill. Maybe he has to journey to a long - forgotten realm and gather the lost powers of the other six demigods to defeat a new, powerful enemy.
Well, perhaps in the fanfiction, Percy discovers that being the last of the seven gives him some unique abilities that he has to learn to control. He could start having visions of the past and future of the demigod world, and he has to use these visions to prevent a catastrophic event from happening. He might also have to team up with some unexpected allies, like a group of minor gods who are also interested in the fate of the demigod world.
In this fanfiction, it could be interesting if Percy, as the last of the seven, is the only one who can enter a dangerous magical maze that holds the key to saving the world. Inside the maze, he encounters all sorts of challenges and traps that are specifically designed to test his skills and his will. He also has to deal with his own inner demons, as the weight of being the last hope for the demigod world starts to take a toll on him. Along the way, he might find some hidden secrets about the origins of the seven and their true purpose.
One idea could be exploring a different origin for one of the demigods. For example, making Annabeth's mother not Athena but a minor goddess, which would change her whole dynamic and the way she views herself as a demigod. Another plot could involve the seven demigods getting lost in a new, never - before - seen realm in the Underworld. This would test their survival skills and their ability to work together without the help of their usual allies. A third plot could be about a love triangle between two of the demigods and a new character that they meet during one of their quests, which would add an interesting layer of drama to their relationships.
Perhaps Percy discovers a hidden prophecy that involves him sacrificing something dear to him to save the demigod world once and for all. This could lead to a lot of internal struggle as he decides what to do. In the fanfiction, he could journey to places never before explored in the original series to find answers.
Another plot could involve a new threat emerging that is related to the events of 'The Last Olympian'. Say, some ancient power was awakened during the big battle but no one noticed at the time. A group of demigods, led by Percy, has to figure out what it is and how to stop it before it's too late. They might have to journey to some long - forgotten places and face new monsters along the way.
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 exploring Percy's life after the main events. Maybe he has to face a new threat that is related to an ancient prophecy that was overlooked. He could go on a journey with his old friends, like Annabeth, to discover the truth behind it.
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.
Maybe Percy is sent on a quest to Atlantis because there are rumors of a traitor among the Atlanteans who plans to side with the Titans. Percy has to navigate the complex political situation in Atlantis and figure out who the traitor is before it's too late. He also has to deal with the Atlantean magic which is different from what he's used to.
One idea could be that Percy discovers a hidden realm within the world of the Wanderer. This realm has its own set of rules and challenges that he has to navigate. Maybe he meets new demigods there who have been lost for centuries.
One idea could be Percy having to make a deal with a minor underworld god to save Annabeth from a new and strange curse that's slowly draining her life force. He has to complete a series of tasks in the underworld that test his loyalty and courage more than ever before.
Well, perhaps the shield was once owned by a powerful demigod from the past. In the fanfiction, Percy starts having strange dreams about this demigod and the shield's true origin. As he investigates, he realizes that the shield holds the key to defeating a new, emerging evil that threatens not just Camp Half - Blood, but the entire world of gods and mortals. So, he has to figure out how to unlock the shield's full potential.