One possible plot twist could be that Percy, with Zeus as his father, discovers he has the power to control the skies in a way that even Zeus is afraid of. This newfound power could put him at odds with the other gods who see him as a threat to the established order.
Maybe a plot twist could involve Percy's mother. Since Zeus is his father, his mother might have some hidden connection to the heavens that was previously unknown. This could lead to a whole new backstory for Percy and his family, and perhaps a new mission to uncover the secrets of his mother's past and how it relates to Zeus.
Well, a really interesting plot twist could be that Zeus made Percy a demigod not just by accident or for the usual reasons. What if Zeus had a premonition that Percy would be the key to saving the gods from a future threat that only a being with a combination of his divine power and a mortal's tenacity could face? So he engineered Percy's birth in a very calculated way, and as Percy discovers this truth, he has to decide whether to trust Zeus and help the gods or turn his back on them because he feels used.
In some fanfictions, a cool plot twist is that the daughter of Zeus has a power that is only activated when she is in great danger. So, in a battle against a powerful enemy, she suddenly reveals this new power that completely turns the tables. It could be something like the ability to create duplicates of herself, confusing the enemy. Another plot twist could be that she has a hidden bond with a certain weapon, like a sword that has its own consciousness. The sword might choose her as its wielder, and together they have powers that are far greater than expected. And there could be a plot twist where she discovers that Zeus has been keeping a big secret from her about her mother, and this secret changes her whole view of herself and her place in the world of demigods.
One possible plot twist could be that Percy has to hide his dual parentage from the other demigods. Since Zeus and Ouranos are such powerful and controversial figures, the other demigods might see him as a threat or an abomination. Another plot twist could be that Percy discovers a hidden power within him that comes from both Zeus and Ouranos, a power that no one has ever seen before. This could lead to him being hunted by both the gods and the Titans.
One possible plot twist could be Percy's struggle with his new identity. Since Zeus is the king of the gods, Percy might face a lot of envy and even threats from other demigods or minor gods who see him as having an unfair advantage. Another twist could be Percy's relationship with his old friends at Camp Half - Blood. They might feel betrayed or confused as to why Percy has been adopted by Zeus instead of Poseidon.
In this kind of fanfiction, Percy might challenge Zeus over issues like the unfair treatment of demigods. For example, Zeus could be overly harsh on demigods who make minor mistakes while the gods themselves get away with much worse. Percy, being a hero, would stand up for his fellow demigods.
Well, one possible plot could be Percy discovering he's Zeus' brother in a very unexpected way. Maybe through some ancient prophecy that was long forgotten. He'd then have to deal with the power struggles within the Olympian family, as well as his own identity crisis. Another aspect could be his relationships with other demigods changing, as being related to Zeus is a huge deal.
Well, it could be about the daughter of Zeus trying to fit in at Camp Half - Blood. Maybe she has powers that are hard to control, like being able to summon huge lightning bolts at unexpected times. She might struggle with the expectations that come with being the daughter of the king of the gods.
A possible plot could be Percy discovers Zeus has been secretly plotting against some of the more powerful demigods. Percy then challenges Zeus to a duel of sorts, with the fate of the demigods at stake. If Percy wins, Zeus has to stop his plotting and give the demigods more freedom.
Well, the plot could be centered around Percy's attempts to bridge the gap between his father Poseidon and his grandfather Zeus. There have always been tensions between the two gods. Percy, using his unique position, tries to bring peace. But there are forces at work, like some rogue demigods who don't want peace between the two powerful gods. They try to sabotage Percy's efforts, leading to a series of adventures and challenges for Percy.
Another possibility is that Percy discovers some long - forgotten weakness of Zeus. In the world of fanfiction, the author could create a scenario where Percy stumbles upon an ancient prophecy or a hidden secret about Zeus. This knowledge could give Percy the upper hand. He could then use his wits and his powers to exploit this weakness and defeat Zeus.
One possible plot could be that the entire Greek pantheon is thrown into chaos. Percy might be seen as a huge threat, and other gods and goddesses would either try to hunt him down or form alliances with him out of fear or a desire for power. Demigods would be forced to take sides, leading to massive battles among them.