One idea could be that the forgotten one has a special power that is the key to saving the world from a new, unknown threat. Another could be that they are actually a long - lost relative of Percy's and their connection reveals hidden secrets about the demigod world. Maybe the forgotten one was sent away on purpose by an enemy long ago and now they're back for revenge.
One idea could be that the forgotten demigod discovers a hidden power within themselves that is related to an ancient and forgotten god. This power could set them on a journey to find out more about their heritage and also put them in a position to save the demigod world from a new threat.
One idea could be exploring the backstory of the forgotten warrior more in - depth. Maybe they were once a great hero in a forgotten era of the Percy Jackson universe and got lost in time somehow. Another could be that the forgotten warrior has a special power that is now needed to defeat a new, emerging threat. They could be a key to unlocking an ancient prophecy that no one has understood until now.
Maybe in the fanfiction, Percy stumbles upon a forgotten legend about a magical artifact that has the ability to rewrite the fates of demigods. The catch is that it's hidden in a realm that is slowly being consumed by chaos. Percy, along with his friends, must navigate this dangerous realm filled with strange creatures and illusions to find the artifact before it falls into the wrong hands. They'll also have to deal with the fact that the gods are not too keen on this artifact being found as it could disrupt their carefully crafted plans for the demigods.
In 'percy jackson forgotten primordial fanfiction', there could be the idea of Percy having to deal with primordial forces that were previously unknown. This could lead to new alliances and challenges. Maybe he has to find a way to communicate with these forgotten entities, which would be a whole new aspect compared to his usual battles with known monsters and gods.
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.
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.