I don't know for sure since it's a fanfic. It could be the dragon king himself as a main character. There might also be a brave knight or a wizard who has to deal with the dragon king or the things in his shadow.
The shadow king himself is of course a main character. He's the central figure around which most of the events revolve. There's also a young apprentice who plays an important role in the story. His loyalty and growth are significant aspects of the narrative.
As I don't know the particular 'the dragon king novel', I can't say for sure. But likely the dragon king himself is a main character. There might also be characters like his advisors, who could be other dragons or magical beings. Maybe there are some humans who interact with the dragon king, either as friends or foes.
The main characters are obviously the king and the dragon. The king is often the one who has to take on the role of protecting his kingdom from the dragon, which is a menacing threat.
I'm not entirely sure as it could be many things. It might be a fan - made story based on a work where there's a dragon king. It could involve adventures in the shadowy realm related to this dragon king character, perhaps with battles, quests, or the exploration of a mysterious world that exists in the shadow of the dragon king's domain.
I'm not sure exactly who the main characters are as I haven't read the story. But surely the king without a shadow is one of the main characters. There might also be some advisors or servants in his court who play important roles in relation to his situation.
Well, Naruto himself is likely to be one of the main characters. Since it's about his shadow, he would be central to the story.
If it's a crossover, there could be main characters from both the 'The Shadow' world and the other world it crosses over with. For example, if it crosses over with a detective story, there might be a famous detective from that story as a main character along with 'The Shadow'. They could have a conflict or work together depending on the plot.
There might be a young apprentice who stumbles upon the Temple of the Dragon King and becomes involved in its affairs. There could also be a villainous character who wants to use the power of the temple for evil. Another possible main character could be a spirit or a creature that has a connection to the Dragon King and the temple.
The main characters are obviously the king and the fiery dragon. The king represents the human side, the leadership and the will to protect the kingdom. The fiery dragon is the antagonist, a powerful and dangerous creature.
I don't know for sure. But I would guess the dragon king himself is a main character. There might also be a brave knight or a wise mage.