There could be some original characters created specifically for this fanfic. For instance, an old hermit who found the abandoned child when they were just a baby and raised them until they were old enough to start their own journey. This hermit could have some hidden knowledge or power that is passed on to the abandoned child, making them a key figure in the story as well.
Sasuke could also be a main character. He might start off as an antagonist to the abandoned child, seeing them as a threat or simply not trusting them. But as the story progresses, their relationship could evolve. And then there could be Kakashi, who might be the one training the abandoned child in the ways of the ninja.
Sakura could be a main character. She might be the one who discovers the abandoned child and tries to figure out what to do. Kakashi could also be involved. He has a history with Naruto and might be torn between loyalty to Naruto and doing what's right for the child. Sasuke could be another character. He might return to the village and get involved in the situation, either to help or because he has his own motives regarding Naruto's actions.
Obviously Naruto would be one of the main characters as it's about him being the neglected child. Other characters from the original Naruto series like Iruka, Sasuke, or Sakura could also be main characters, depending on how they interact with Naruto in this fanfic.
In this fanfiction, Naruto is the central figure. Alongside him, we might expect to see characters like the Raikage from Kumo. Their interactions and differences in ideologies could be a major part of the story. There could also be some minor characters from both Konoha and Kumo who help to build the background and context of Naruto's decision to abandon Kumo, like the shopkeepers or other common shinobi who witness the events leading up to this big decision.
The main characters in 'child of grace fanfic' could be the 'child of grace' themselves, of course. There might also be friends or allies that they make along their journey. These could be other characters with their own unique abilities or personalities that complement or contrast with the 'child of grace'. For example, a street - smart character who helps the somewhat naive 'child of grace' navigate the more practical aspects of the fictional world they live in.
The main character is likely the 'child of mine'. But there could also be supporting characters such as the parents or guardians of the child. They might play important roles in the child's life within the fanfic.
Well, obviously the child of Jormungand would be one of the main characters. There might also be characters who are guardians or mentors to the child, guiding them through their journey. And perhaps there are antagonists who oppose the child because of their lineage.
I'm not sure specifically as I haven't read this particular fanfic in detail. But usually in such fanfics, there could be a central hero or heroine who has some special qualities or abilities related to the 'child of heaven' concept.
There might be other characters who are friends or allies of the 'child of the stars'. They could be from different backgrounds, like a group of adventurers who team up with the 'child of the stars' to face various challenges. These characters would add depth and variety to the story.
In a 'child of the phoenix fanfic', the main character would be the child of the phoenix of course. They would be the focus of the story. There could be other important characters too. For instance, the child's family members might be part of the story, even if they are not phoenixes themselves. They could provide emotional support or be a source of conflict. Another possible main character could be a love interest for the child of the phoenix. This character could add a romantic sub - plot to the story and also influence the decisions and actions of the child of the phoenix.
In most of these fanfictions, Naruto is a central figure as he is the protagonist of the Naruto series. His character traits like his determination and kindness play a big role. Scorpion is also key as the story often revolves around his abandonment and what he will do next. Sometimes other characters like Sakura or Kakashi might also make an appearance to help Naruto deal with the situation involving Scorpion.