Well, it could involve Percy having some sort of special connection with the Fates. Maybe he can influence destiny in ways others can't. For example, he might be able to change the fates of his friends in dangerous situations, like when they're facing a powerful monster. This would make for an interesting dynamic as he'd have to balance the power he has with the natural order of things.
His powers might become more related to fate - manipulation. He could, for instance, foresee certain events related to the destinies of people or creatures. This would give him an edge in battles as he could anticipate the moves of his enemies based on their fated paths.
Obviously, Percy Jackson is the main character. But there could also be Annabeth Chase, his long - time friend and love interest. Grover, his satyr friend, might also play an important role. And since it's related to the Fates, the three Fates themselves - Clotho, Lachesis, and Atropos - could make appearances, either as allies or antagonists depending on the story.
Well, sometimes in fanfiction, his brother might be a mortal who discovers his demigod heritage later. This could add an interesting twist to the story as he has to adapt to the world of gods and monsters. Or it could be a long - lost half - brother from a different camp, like a son of Poseidon from another part of the world who was hidden away for some reason.
One interesting plotline could be Percy having to deal with the complex powers and expectations that come with being the 'Son of the Fates'. Maybe he has visions of different possible futures and has to figure out how to navigate them to save his friends and the world. Another could be his interactions with other demigods who are either in awe or afraid of his new status.
A powerful Titan who has somehow escaped Tartarus and is bent on revenge against the gods could be a great antagonist. This Titan might see Percy as a key figure in the new order of the gods and fates, and so wants to destroy him. Maybe it's someone like Atlas, who has a long - standing grudge against the Olympians and now wants to take it out on Percy as the champion of the fates.
A group of powerful and corrupted demigods could also serve as antagonists. They might have been promised great power by some dark force if they can disrupt the work of the Fates. So they set out to target Percy and try to stop him from fulfilling his role as the God of Fates.
Percy could develop by becoming more responsible. As the adopted son of the Fates, he has a greater role in the grand scheme of things. So he might start thinking more about the long - term consequences of his actions.
There's a fanfiction called 'Brotherhood in Camp Half - Blood'. In this story, Percy's new brother is introduced in a very dramatic way. The author does a great job of showing how the brother fits into the world of Percy Jackson, with lots of action and adventure sequences. It also explores the relationship between the two brothers in depth, like how they deal with the challenges together and support each other in the face of danger.
Well, a plot idea could involve Percy being cursed by the fates to forget his own identity. He then has to go on a journey to rediscover who he is while still fulfilling his duties as the champion of the fates. Along the way, he might meet old friends who don't recognize him at first, and he has to prove himself to them. Or perhaps the fates send Percy on a mission to prevent a prophecy from coming true that would destroy the entire demigod world. This would involve him traveling to different mythological places and facing powerful enemies.