Definitely Naruto. He would be the central figure through which the story unfolds. In addition to him, if the fanfiction delves deep into the Shikon side, Inuyasha could be another main character. Their interaction would be really interesting as they come from different worlds and have different powers. Also, depending on how the author writes it, characters like Kakashi from Naruto might also play significant roles, perhaps as a guide or mentor to Naruto in this new and strange world of the Shikon fanfiction.
I'm not sure specifically as I haven't read this exact fanfiction. But generally, it might combine elements from Naruto and the Shikon no Tama (Jewel of Four Souls) concepts. It could involve Naruto characters in a story related to the power of the Shikon Jewel, perhaps with Naruto on a quest to obtain or protect it.
Kankuro is another possible main character. He's a puppeteer from the Sand village. Fanfiction might delve into his growth as a ninja, his relationships with his siblings, or his development of new puppet techniques.
Obviously Naruto is one of the main characters. Given the title, he has a significant connection to the Juubi in this fanfiction.
Obviously, Naruto himself is a main character as the story revolves around his revival. His friends like Sasuke, Sakura, and Kakashi are also likely to be main characters. They would be involved in the process of bringing Naruto back or in helping him adjust to his new life after revival.
Often, there are original characters created specifically for the fanfiction that interact with Damocles and Naruto. These characters could be other ninja from the village, or perhaps outsiders who bring new challenges or perspectives to the story. They might have unique abilities or backstories that tie into the overall plot and help drive the story forward, making the interactions between all the characters more interesting and complex.
Since it's fanfiction, the main characters could be a mix of the original Naruto characters and some new ones created by the author. The formless concept might be centered around a new character who has the power to change the Naruto world in some way, and Naruto and his comrades have to deal with the consequences. Maybe it's a formless being that has some connection to an ancient ninja clan, and Sasuke gets involved in uncovering the mystery.
Obviously, Naruto and Amaru are main characters. Naruto is the well - known protagonist from the original Naruto series, and Amaru is the character specific to the fanfiction who often has her own unique story arc.
Obviously, Naruto and Hippolyta are the main characters. Naruto brings his ninja skills, his strong will, and his experience from the Hidden Leaf Village. Hippolyta, on the other hand, represents the strength and wisdom of the Amazons.
Often, the descendants of the original Naruto characters are main characters. For example, Naruto and Hinata's son, Boruto, might be a central figure.
Obviously Naruto is one of the main characters. And the owner or creator of the mask could also be a main character, whether it's a new character introduced in the fanfiction or an existing character with a new role related to the mask.