There could be a new group of rogue ninjas. These ninjas might be after the same thing as fem Naruto in the hunt. They see her as competition and will stop at nothing to get what they want. They could have unique and dangerous abilities that make them formidable opponents for fem Naruto and her team.
It could be Orochimaru. He's always been interested in power and the hunt for powerful things. He might see fem Naruto as a threat or a potential source of power. He could try to capture her or stop her from achieving her goals in the hunt.
The Akatsuki could be the main antagonists. They are always on the hunt for the tailed beasts. Since fem Naruto has the Nine - Tails, they would be very interested in her. They would send their strongest members like Itachi or Pain to stop her if she's on a hunt that conflicts with their goals.
In this fanfiction, perhaps fem Naruto joins the hunt to prove herself. She might face discrimination at first because she's a female in a male - dominated ninja world. But as she participates in the hunt, she gradually earns the respect of her peers. She could use her shadow clone technique in creative ways during the hunt, like sending clones to scout ahead while she attacks from a different angle.
It could be the ninja from Naruto's former village who don't want him to succeed in his new place. They might see his new - found influence as a threat and try to undermine him.
The main antagonists could be some of the conservative Iwa ninjas who oppose Naruto joining their village. They might see him as a threat to their traditional ways and values. Also, there could be some rogue ninjas from other villages who target Naruto because they see him as an easy target now that he's in a new and unfamiliar environment.
Obviously, Fem Percy would be one of the main characters. There would probably also be the leaders or prominent members of the hunt. Maybe some characters from the original Percy - related stories could also make appearances in different roles, like her friends who might be worried about her new path in the hunt.
One possible plot is that Fem Percy joins the hunt to seek a new purpose. In the story, she could discover hidden powers within herself related to hunting. Along the way, she might form strong bonds with the other hunters, and together they face a great threat that only their combined skills can defeat. For example, a powerful mythical beast that has been terrorizing the lands they hunt in.
One possible main antagonist could be a group of rogue ninjas who are targeting Kumo. They see Naruto joining Kumo as an opportunity to cause chaos. They might try to frame Naruto for various crimes in Kumo to turn the villagers against him and Yugito, who is defending him. Another could be a power - hungry Kumo ninja who doesn't like the idea of an outsider like Naruto coming in and potentially getting more attention or power than they have.
It could be a group within Naruto's own clan who have turned against the rest of the clan due to some ideological differences. They might want to use the clan wars as an opportunity to take over the clan and change its values. Another possibility is a mysterious and powerful ninja from another land who has his own motives for causing chaos during the clan wars.
The Titans could be great antagonists. They might see the Hunt as a threat to their plans for power and send their minions to disrupt it. Percy would have to fight off these minions, like the Telkhines, who are known for their metal - working skills and could create powerful weapons against the Hunt.
There could be a group of anti - military rebels outside the military. They see the military as a tool of oppression and are constantly causing trouble. Percy might have to deal with them, either through combat or trying to negotiate and understand their point of view.
The 'fem Percy Jackson joins the hunt' fanfiction could be full of exciting twists. Given that Percy is known for his courage and quick thinking, as a female, she would likely carry those traits as well. She may form a strong bond with Artemis, the goddess leading the hunt. This bond could lead to her being given special tasks or privileges within the hunt. She might also have to deal with the internal politics of the hunt group, which could be a whole new area of conflict for her compared to her normal adventures.