There's no definite answer as it's fanfiction. However, it's likely that well - known characters like Naruto, Sakura, and Kakashi could be involved. Naruto because he's the protagonist of the original series and always looking for new ways to become stronger. Sakura could be involved in researching the medical implications of the seal if it has any. And Kakashi, with his vast knowledge, could be either helping or hindering the discovery and use of the resistance seal depending on the plot of the fanfiction.
It could be about various things. Maybe it's about a unique form of seal in the Naruto universe that has some sort of resistance property. It might involve characters creating or dealing with this special seal in a fan - created story.
Perhaps there is a wise old seal master who takes the prodigy under their wing. This character could have a lot of knowledge about the history and secrets of seals, and they would play an important role in the prodigy's growth. Additionally, there could be some antagonists, maybe a group of rogue ninjas who want to steal the prodigy's seal knowledge for their own evil plans.
Most likely Naruto would be one of the main characters since it's in the title. And since it's about a faulty seal, characters who are related to Naruto's situation in the original story might also be main characters, like Jiraiya. He was Naruto's teacher and knew a lot about the seals, so he would probably play an important role in this fanfiction.
There could be a rival character, a fellow ninja who is jealous of the seal master's skills with the Hiraishin. This rival might constantly try to undermine the seal master or steal their techniques, adding a layer of conflict to the story.
Often, the main character is the secret seal master themselves. They are usually highly skilled in the art of seals and have a deep understanding of the ninja world's secrets related to seals.
Sasuke could also be a prominent character. His skills and knowledge, especially his Sharingan which can help in deciphering and breaking seals, make him a likely candidate. He may be driven by his own goals, such as seeking revenge or power, and seal - breaking could be a means to an end for him in these fan - created stories.
Obviously Naruto himself is a main character as the memory seal is related to him. Sasuke could also be involved, as he has a deep connection with Naruto and might notice the changes in him due to the seal.
Kakashi could play an important role. As Naruto's former teacher, he would surely want to help Naruto understand and control the Caged Bird Seal. He could use his knowledge and experience to guide Naruto. Another character could be Jiraiya. Even if he's not alive in the original story at a certain point, in the fanfiction, he might return as a spirit or something to give Naruto advice about the seal.
Well, the main character is likely to be the seal master. This person is probably highly skilled or on a journey to become highly skilled in the art of seals. There may also be other characters from the Naruto universe who interact with the seal master, like Naruto himself. Naruto could be a friend or a rival to the seal master, depending on how the story is written.
Well, Naruto is without a doubt a main character in these fanfictions. He's the one exploring the world of seal sage arts. But there are other characters too. Tsunade might be involved, perhaps providing resources or support for Naruto's seal sage journey. Another character could be a rival ninja from another village who is also interested in seal sage techniques. This rival could create conflicts and challenges for Naruto as they both vie for the same powerful knowledge. And then there are the supporting characters like Shikamaru or Sakura who might offer their own unique perspectives and assistance to Naruto in his seal sage - related adventures.