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.
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.
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.
The characters included: The main character-Adele Dry Red, the girl with the blood of the devil; the supporting character-Barbara Vidwich, Mrs. Vidwich, Adele's godmother and mentor; the supporting character-Darcy Dry Red, Adele's younger brother; the supporting character-Evan Ledragon, the king of a thousand years ago, the mysterious man; the supporting character-Loreya Dragunov, the princess of the Dragon Kingdom; the supporting character-Sherlock Lovecraft, the chief magician of the Dragon Kingdom; the supporting character-Marshall Zacharias. The dean of the Agate Staff Academy, the former court pharmacist, the female protagonist-Isabella Woods, the daughter of the woodcutter, and Adele's best friend. "Demon Girl Adele" by Mai Aming. It was a fantasy/sword and magic novel with sword and magic, transmigration, and magic elements. "A traditional western fantasy adventure story. The female protagonist of an ordinary person was captured by a demon god. After her soul slept for ten years, she found herself residing in her 25-year-old body. At the same time, her body also obtained a super strong regenerative ability. She had two souls in one body. The story began... I hope you will like this book.
There could also be a male character who is caught in the middle of the good girl and the bad girl. He might be attracted to both of them for different reasons. He could be a jock who is used to getting attention from girls, but the good girl and the bad girl present him with different challenges. He has to decide which one he really wants to be with, and this decision could be based on his own growth and values.
I don't know the exact characters in 'the snow girl novel' since I haven't read it. But there must be the snow girl herself as the main character. There could also be other characters like a love interest, perhaps a young man who is intrigued by her uniqueness.
I don't know as I haven't read it. But it could be the summer girl herself, her friends, and maybe her family members.
There is also her mentor, who plays an important role in guiding her and helping her understand her powers better. He has a wealth of knowledge and experience that he imparts to her.