It's hard to say without reading it. However, it's likely that there will be a protagonist who is either drawn into or forced into the femdom world. There could be a mentor - like female character who guides the main character through the rules and ways of this world. And there may be other characters who oppose or support the main character's journey.
The school librarian could be a main character in a femdom school story. She controls the access to books, which is a powerful position. She might have strict rules about borrowing and returning books, and if students break those rules, she has her own ways of dealing with them, like making them help with library chores for a week.
I don't know as I haven't read it, but likely the main characters would be the women in stockings who are in the femdom role.
I don't know the main characters as I haven't read the novel.
Obviously, the pony boy would be one of the main characters. And there would be the dominant female or females. Maybe a strict mistress who controls the pony boy's life.
Typically, there is the dominant female figure. She is often strong - willed, confident, and in control. Then there's the submissive character, which could be male or female, who obeys the commands of the dominant female. There might also be secondary characters who either support the dominant female's authority or are observers of the femdom relationship.
Without having read the 'the world in 9 1 2 novel', it's impossible to accurately name the main characters. However, if we assume that the numbers 9, 1, 2 are related to the characters in some way, perhaps there are nine siblings and one of them, the firstborn (represented by 1), has a special relationship with a character who is an outcast or different in some way (represented by 2). But again, this is just wild speculation.
In this type of story, the central character is surely the femdom figure. She is the driving force behind the breeding program. There could also be veterinarians who play a role as they are important for the health of the 'cocks' in the breeding program. Additionally, there might be other characters like suppliers who provide the necessary food and equipment for the breeding. But the femdom character is the one who has the overall control and makes the major decisions.
Since I don't have knowledge about the 'A Day in Berlin Femdom Story', I can't name the main characters. Maybe there are some readers' comments online that could give you an idea about the characters.
The main characters in the '7 wonders of the world novel' could be a diverse group. There might be a young and curious protagonist, perhaps a journalist or a student, who embarks on a journey to learn more about the seven wonders. There could also be some antagonists, like treasure hunters who are willing to destroy the wonders for their own gain. And there may be local people living near the wonders who play important roles in the story, sharing their knowledge and traditions.
The main character in the Magus World novel is Lei Lin. He is a key figure in the story and drives much of the plot forward with his actions and decisions.