It could also be an established character from the Naruto series who somehow acquires the Ink Release. Maybe Sasuke, during his travels, encounters a strange sage who gives him the power of Ink Release. He then has to adapt his fighting style to incorporate this new ability.
One potential main character could be a new ninja who discovers they have the Ink Release. They are an outcast in their village at first because of this strange power but then learn to master it and become a hero. For example, a young orphan who is bullied for having this unusual ability.
Well, it could be an original character created specifically for the fanfiction. This character might be an outcast because of their Darkness Release abilities. Maybe they are trying to prove themselves in a world that fears their power.
There could also be a villain in the fanfiction who wields plasma release in a menacing way. This character might be from a secret organization, using the power to further their evil plans. Their plasma - based attacks would be a major threat to the heroes, forcing them to find ways to counter this dangerous ability.
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.
The main characters could be a new generation of ninja students in the Naruto world. They stumble upon the knowledge of 'Nightmare Release' and have to deal with the consequences. This could include a young ninja who has a natural affinity for this strange power and has to learn to control it while facing the challenges from other ninjas who fear or want to use this power for their own gain.
It's hard to say for sure as it's fanfiction. But it could be an original character created by the fan writer who has the Mirror Release ability. Maybe it's also Naruto himself who discovers this new type of release during his adventures.
Obviously Naruto himself would be a main character. He could bring his unique ninja skills and his determination to the story. Another could be Noctis from Lucis Caelum. His powers and his role as a prince could add a lot of drama and action to the fanfiction.
Obviously Naruto and Sasori. Naruto as the'son' would be the central figure in terms of the story's development. And Sasori, as his 'father' in this fanfiction, would play a crucial role in shaping Naruto's growth.
Orochimaru is another possibility. He is already somewhat of an evil genius in the original Naruto series. In a fanfiction, he could be further developed as the main character, perhaps with his experiments taking on even more extreme and far - reaching consequences. His actions and plans could be the central focus of the story, with other characters either trying to stop him or being caught up in his schemes.
Naruto and Shinso are the primary ones. But we could also have an old and wise vampire elder as a main character. This elder could have knowledge about a prophecy that involves Naruto and Shinso, and his actions and decisions would drive a lot of the plot as he tries to either fulfill or prevent the prophecy.
A potential main character could be a long - lost relative of Hashirama who has the mokuton ability but has been neglected in the main Naruto story. This character could then embark on a journey to discover their true power and place in the ninja world.