If Percy kills Zeus, it could also lead to a power vacuum. Percy might not have intended to rule, but he could be pushed into a position of trying to maintain order. This could involve him trying to restructure the way the gods interact with mortals and demigods, perhaps creating a more equal and just system.
Another aspect could be the reaction of the mortal world. With Zeus gone, natural disasters and strange phenomena might occur more frequently at first. Percy would have to deal with not only the supernatural consequences but also the panic and blame from the mortals who don't understand what's really going on.
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.
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.
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, 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.
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.
It could also be about power. Percy might realize that with Zeus out of the way, he can reshape the world of the gods in a more just and fair way. He could believe that Zeus's rule is corrupt and that killing him is the only way to bring about real change.
Fanfiction often takes creative liberties. In this case, it might be that the author wanted to explore new power dynamics and character interactions. If Percy was Zeus' brother, it would completely change the power balance in the world of the series. Percy's connection to the sea and Zeus' control over the sky could lead to all sorts of interesting plotlines, like joint quests or power struggles between the two 'brothers'.
One possible reason could be a misinterpretation of a prophecy. Maybe Artemis believes Percy is a threat to the natural order she protects based on a wrongly interpreted prophecy. For example, if a prophecy was worded ambiguously and she thought Percy would bring destruction to the wild, she might take drastic action.
One possible motive could be some sort of mind control. Maybe a powerful enemy has the ability to control Percy's actions and forces him to go after Artemis. This would add an element of tragedy as Percy would be acting against his will.
The balance in nature would be disrupted. Artemis is the goddess of the hunt, the moon, and nature. Her death could cause strange phenomena in the natural world, like animals going wild or the moon's cycle becoming erratic. This would not only affect the demigods but also mortals who depend on the stability of nature.