Kakashi is another fan favorite. Fanfiction often delves into his past more deeply, or shows him taking on new challenges and mentoring the younger generation in ways that weren't shown in the original series. For example, he could be training Naruto in a very specialized and secret jutsu that only he knows.
Obviously, Naruto himself is always a popular character. His determination and growth throughout the story are always interesting to explore further in fanfiction.
One interesting plot could be Naruto having a secret power that he discovers during a new and dangerous mission outside the Hidden Leaf. This power might be related to an ancient jutsu that only he can unlock due to his unique chakra nature.
Haku is another beloved character in these fanfictions. His selfless loyalty to Zabuza and his gentle yet deadly nature are often explored further. Writers might create scenarios where Haku survives and has a different path in life, perhaps using his skills for more peaceful purposes within the Hidden Mist village.
Naruto himself is often a popular character in these fanfictions. Writers like to put him in new situations where he has to use the hidden blade. Sasuke is also popular as he can easily be integrated into stories involving new and powerful weapons like the hidden blade.
Sasuke Uchiha is also a great character to feature. His complex personality and his quest for power and revenge can be explored in different ways. Maybe a fanfiction where he has to make a choice between his loyalty to the Leaf Village and his thirst for power in a new and unexpected situation.
Haku is also very popular. His loyalty to Zabuza and his gentle yet powerful nature are appealing aspects. Fanfictions might explore his life in the Hidden Mist Village more, like his training and how he came to be so skilled at using his ice - related jutsu.
It could be a rogue ninja from another village who wants to use the demon within Naruto for his own evil purposes. He might be power - hungry and sees Naruto as a tool to gain control over the Hidden Leaf and other ninja villages.
Kakashi is a character that some fanfictions play with in terms of hidden gender. As a very popular and mysterious character, changing his gender can bring out new aspects of his personality. His relationship with his students, especially Naruto, Sasuke and Sakura, would be very different. Also, Itachi could be a character where a hidden gender aspect in fanfiction can create a whole new set of storylines and emotional arcs.
Kakashi is another beloved character. Fanfic writers can focus on his past in the Hidden Village, perhaps revealing more about his time as a member of the ANBU black ops. They could also write about his role as a teacher in new and exciting ways, like training a group of misfit ninjas to become an elite squad.
Sasuke is also frequently featured. His relationship with Naruto, whether it's as a rival or a partner in protecting the village, adds a lot of depth to the stories. In some fanfictions, Sasuke might play a crucial role in helping Naruto deal with threats to the village from the shadows.
Naruto himself is obviously a very popular character in such fanfictions. Since the stories often revolve around his hidden powers. Sasuke is also commonly involved as his rival. Their relationship and the contrast between Naruto's newfound hidden power and Sasuke's own abilities make for interesting storylines. Sakura can also be a key character, maybe she plays a role in helping Naruto discover or control his hidden power. Kakashi too, as Naruto's former teacher, could be involved in guiding Naruto in understanding and using this hidden power.