Often, there are also antagonist assassins who are main characters in a sense. They drive the plot by creating conflict. These assassins could have their own motives, like working for a powerful and shadowy organization. Their backstories, which might include things like being orphans trained from a young age to be killers, can add depth to the fanfiction.
Sometimes, it could be a reimagined version of an existing 'naruto' character who discovers they have this assassin bloodline. For instance, Sasuke could be written to have a hidden assassin bloodline that awakens, leading to a whole new set of adventures and power - ups for him.
I'm not entirely sure as it depends on the specific fanfiction. But it could include Naruto himself along with some newly created assassin characters.
In many Naruto Fox Assassin fanfictions, the Fox Assassin themselves might be the sole main character. Their journey of self - discovery, their battles, and their growth as a character are the central focus. However, in some cases, side characters like Kakashi could play an important role too. He might be the one who initially discovers the existence of the Fox Assassin or provides some guidance or opposition to the Fox Assassin depending on the plot of the fanfiction.
Naruto himself could be a main character in such fanfiction. Maybe he gets framed for pickpocketing and has to clear his name while also dealing with the real pickpocket who is causing chaos in the village.
The main characters can include the gunsmith, who might be an outsider to the traditional ninja world but has a unique skill set. Another could be a ninja who becomes the gunsmith's protector or partner. For example, Sasuke could be interested in these new firearms as a way to enhance his own power. And sometimes, there are original characters created specifically for the fanfiction, like a rival gunsmith who tries to outdo the main gunsmith in creating the most powerful weapons.
Naruto is the central character in 'naruto dark naruto fanfiction'. But characters like Orochimaru can play a big role. He might see an opportunity in a darker Naruto and try to manipulate him for his own gain. Hinata could also be a main character in some fanfictions. Her love for Naruto might be put to the test as she tries to understand and save Naruto from his dark path. And the Sannin, especially Jiraiya, might be involved as they were important in Naruto's development in the original and could have a role in dealing with his new, darker nature.
Obviously Naruto himself is a main character. He is the one with the pacemaker so he is central to the story. Sasuke might also be involved. He could be initially skeptical of Naruto's new situation with the pacemaker but then come around to help. Sakura too, as a medical ninja, she could play a crucial role in understanding and perhaps even trying to modify the pacemaker.
Naruto himself is often a main character. Since it's related to the Naruto world, he could be exploring the mansion, looking for something important or just having an adventure there. Sasuke might also be featured, maybe he's there to train in seclusion within the mansion.
Kakashi could be a main character in such fanfiction. He is a skilled ninja and could potentially teach Naruto about the bow, its history, and how to use it effectively. Another character could be Itachi, who might have some connection to the bow's origin or some hidden knowledge about it that he imparts to Naruto in a complex and mysterious plot.
Sasuke is often paired with Naruto Fernandes in fanfiction. Their complex relationship in the original Naruto series lends itself well to new and interesting storylines in fanfiction. They could be on a new mission together, or perhaps have a different kind of rivalry that goes beyond the typical power struggle.