Another possible main character could be an antagonist. This could be a powerful being, either human or demon, who sees the demon girl as a threat or an abomination. They might try to hunt her down or stop her from achieving her goals, which could range from finding a place in the world to using her powers for good. Their actions and the conflict they create are central to the story of the 'demon girl novel'.
In some 'demon girl novels', there could be other demon characters as well. For instance, her family members or other demons from her clan who play important roles. They might have different views on how the demon girl should interact with the human world or use her powers. Additionally, there could be a mentor - like figure, perhaps an old and wise demon or a human with special knowledge, who guides the demon girl on her journey.
Since I haven't read it, I can't be certain. But I would assume the demon girl is one of the main characters. There may also be other demons or characters that interact with her, like perhaps a strict demon who is in contrast to her lax nature.
A local witch or wizard could be a main character. They sense the presence of the demon and come to help the girl. They might have their own motives, like they want to use the demon for their own gain or they truly want to save the girl from the demon's clutches.
Demon Copperhead is surely a main character. There could be other characters such as a mentor figure who helps him in his journey, or a rival who makes his life more difficult. Also, there might be some characters from his family, like a mother or father figure, who influence his development.
The main character is Demon Copperhead for sure. There might be other important characters such as his family members, friends, or perhaps people he meets during his journey. These could include his parents if they play a significant role in the story, or a mentor - like figure if there is one in the plot. Without reading the novel fully, it's hard to name all of them, but they would be characters that interact with Demon Copperhead and influence his story in important ways.
There could be a wise old mentor figure. This person might be aware of the girl's actions or the existence of demons in general. They could try to guide the girl, either to stop her from summoning the demon in the first place or to help her once the demon is there.
There could be a hero - perhaps a brave woodsman or a curious explorer who is not afraid to face the unknown. And of course, there would be the demon as a major character. There might also be a wise old figure, like an elder in the nearby village who knows some secrets about the demon in the wood and helps the main character on their journey.
I don't know the specific main characters in 'the damned demon light novel' as I haven't read it. However, it's likely that the damned demon itself is a main character. There could also be other characters like a hero who opposes the demon or a sidekick of the demon.
The protagonist is Nie Li. He is a very intelligent and determined character. He has the knowledge from his previous life, which gives him an edge in this new life to strive for power and change the fate of his loved ones.
Since it's a demon - related graphic novel, there might be a powerful demon as a main character. This demon could have some special abilities or a complex backstory that drives the plot in volume 1. There could also be a human character who gets involved with the demon world, perhaps accidentally, and then becomes central to the story.
I don't know for sure since I'm not familiar with a specific 'demon and god light novel'. But typically, there could be a brave human or demi - god as the protagonist, a powerful demon as the antagonist, and perhaps some wise god - like figures as mentors or allies.