Well, Naruto is the central figure. But depending on the direction of the fanfiction, characters like Kakashi could play important roles. He might be the one trying to guide Naruto back from this dark path. And then there could be new characters created specifically for this fanfiction, like a dark entity that is the source of the hellfire that has affected Naruto.
In this 'dark naruto hellfire fanfiction', Naruto is surely a main character. Alongside him, we might see his friends and allies from the Naruto universe. However, the fanfiction could also introduce some antagonist characters related to the hellfire concept. Maybe a demon or a dark wizard who wants to use Naruto's newfound hellfire powers for their own evil purposes, and these new characters would also be important in the story.
Well, it could be about a darker version of Naruto in a world filled with hellfire - perhaps Naruto with a more sinister side, facing challenges in a hellish setting. Maybe it's a story where his powers are related to hellfire in some way.
Typically, the main character is the dragon slayer. They are often a brave and determined individual with unique skills and a strong will.
Since it's a fanfiction, it could still have Harry Potter as a main character. Maybe Hermione and Ron are also involved. There could also be some original characters created specifically for this fanfiction that are part of the Hellfire group.
There could also be some original characters created specifically for this fanfiction. For example, a powerful ninja who has knowledge about the merge process and tries to either help or hinder Naruto. Or perhaps an ancient spirit that was somehow involved in the creation of Dark Naruto in the first place and now has an interest in the merge.
Obviously, Naruto would be one of the main characters, just in his new 'dark lord' role. Sasuke could also be a major character, as his relationship with Naruto is so central in the original series. Their dynamic would likely be very different in this fanfiction, perhaps becoming more of an adversarial relationship.
It really depends on the specific fanfiction. However, it could potentially include Naruto himself, as he is a central character in the Naruto universe. And perhaps some of the main characters from 'Dark Angel' like Max might also be incorporated. There could also be new original characters created by the fanfiction author to bridge the two universes.
Naruto is the central character here as he's the one in the role of servant of the dark. There could be other characters like an ancient dark wizard or a powerful demon who are pulling the strings and making Naruto do their bidding. His sensei Kakashi might also be involved, either trying to bring Naruto back or being conflicted about how to deal with him now that he's on the dark side. Additionally, villains from the original Naruto series could have a more prominent role in this fanfiction, working with Naruto in the dark or against him depending on the plot.
Since it's a Naruto - based fanfiction, Naruto himself would likely be a main character. There may also be other characters from the original Naruto series like Sasuke, Sakura, or Kakashi who could be involved in his journey as a dark sage.
Obviously, Dark Naruto would be one of the main characters. He is the center of this fanfiction concept. Other than him, characters like Sasuke would likely still play important roles. Sasuke might be either an ally or an adversary to Dark Naruto, depending on how the story is written. Also, characters like Kakashi Sensei could be there to try and guide or stop Dark Naruto, given his new, more dangerous state.
There might be a mentor - like figure who has some knowledge about the dark release. This character could be important as they guide the younger or less experienced character with the dark release. Maybe they have a hidden past related to the power as well. In some fanfictions, this mentor could be an old ninja who has seen the power's potential and destruction in the past.