One possible plotline could be that Shield has been corrupted in this fanfiction. Maybe they see Percy as a threat to their new order or some secret project. They might use his demigod powers against him, perhaps by using some high - tech device that messes with his connection to the gods. This could lead to Percy being physically and mentally tortured as he tries to resist and figure out a way to break free.
A plotline could be Percy having to face his own fears and insecurities while being tortured. Maybe he starts to doubt his abilities and heroism. But as the story progresses, he overcomes these doubts through his willpower. Also, the fanfic could explore how the torture affects his relationship with the gods. He might feel betrayed by them for allowing him to end up in Tartarus and this could lead to a change in his loyalty or attitude towards them.
In some fanfictions, Percy's torture in Tartarus could be part of a grander scheme. For example, an enemy on the surface world has made a deal with the forces of Tartarus to weaken Percy. As he endures the torture, he gradually uncovers the conspiracy and tries to find a way to not only escape but also stop those who sent him there. His friends, unaware of his situation at first, start to suspect something is wrong and embark on a quest to find out what happened to him and rescue him.
Well, perhaps in the fanfiction, Percy is tortured by Kronos in a way that involves his demigod powers being slowly drained. This would make him feel weak and vulnerable, which is a huge contrast to his usual strong self. His torture could also be a way for Kronos to try and break his spirit so that he can turn Percy to his side. Meanwhile, the gods might be debating whether or not to interfere, adding another layer of conflict to the story.
Well, perhaps the plot could center around Percy's journey to discover his true self and his purpose. Nyx, being his caregiver, might have her own motives for raising him. Percy could be on a quest to find out if Nyx has some grand plan for him. Along the way, he would encounter various challenges. He might have to battle creatures that are native to Nyx's domain. His powers would evolve in unique ways. For instance, he could have the ability to communicate with nocturnal animals or control the night itself in some small ways. His relationship with Nyx would also be complex, with moments of love and respect, but also times when he questions her actions and decisions.
Another possibility is that there are some good - hearted Shield agents who discover the truth about Percy. They could form an underground resistance within Shield. They might be people who have always been skeptical of the harsh treatment of Percy. They could then work together to free Percy and expose the wrongdoings of those in Shield who ordered the torture.
One possible plotline could be Percy Jackson finding himself in the 1700s and having to deal with the different forms of mythological creatures that were more prevalent during that time. Maybe he has to stop an ancient evil that was sealed away centuries ago but is now being awakened in the 1700s due to some dark magic rituals.
Perhaps Percy is lost and ends up in the Japanese mythological world. Amaterasu, seeing his unique powers from a different pantheon, decides to help him find his way back. Along the way, they exchange knowledge about their respective mythologies. Percy teaches her about the Greek gods and their quirks, while Amaterasu imparts wisdom about the Japanese spiritual world. This could lead to a mutual respect and a new friendship that bridges the two mythologies.
A possible plotline could be Percy being assigned to a top - secret mission by Shield. He has to use his unique skills to infiltrate an enemy organization. Another plotline might be that Percy discovers a conspiracy within Shield itself and has to decide who to trust while trying to expose it.
Another plot could involve Percy Jackson being sent to Jack Darby's world. Percy would have to deal with the new technology and different threats there. Maybe he discovers that some of the ancient monsters from his world have a connection to the technology in Jack's world. Jack and Percy would then have to team up to stop these threats from spreading chaos in both their worlds.
One possible plotline could be Percy gathering a powerful group of demigods and allies. They might embark on a quest to find the ultimate weapon that can defeat Gaea. Along the way, Percy could face many internal struggles, like doubts about his own abilities. He might also have to make some tough choices that could endanger his friends but are necessary to defeat Gaea.