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 also be new characters created specifically for this fanfiction. These could be allies or enemies of the 'Child of Heaven', adding more complexity to the story. For example, there could be a group that wants to use the 'Child of Heaven' for their own dark purposes, and the Fairy Tail guild has to stop them.
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.
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.
Ciel is surely the central figure. However, there could be other characters from the original source material that have also passed on and are in heaven. Additionally, there may be original characters created for the fanfic, such as a special angel who has a particular connection with Ciel. There might also be antagonists in the form of fallen angels or some sort of heavenly bureaucrats who oppose Ciel for some reason.
It's hard to say without actually reading the fanfic, but it could feature Naruto himself as one of the main characters, perhaps with some new abilities related to 'heaven' and 'earth'.
Obviously, the child of the emperor would be one of the main characters. There could also be a loyal servant or bodyguard who has been with the child since birth and helps them through their trials. And perhaps an antagonist like a power - hungry noble who wants to get rid of the child to gain more power in the court.
Well, obviously the 'child of dark prophecy' is one of the main characters. This character is likely to be at the center of the story, with their actions and decisions driving the plot forward.