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.
Well, it could be about a pony boy who is in a world where female dominance is the norm. He might have to perform tasks assigned by the dominant females, like in a role - playing scenario where he is treated as a pony and has to follow their commands.
Since I don't know the exact 'pony boy story', the main characters are likely to be the pony boy himself and, of course, the pony. There might also be other characters like the boy's family members, friends in the neighborhood, or people he meets during his adventures with the pony.
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.
Obviously, the orphan boy is the central character. Additionally, there might be a strict but fair orphanage caretaker. And there could be a wealthy benefactor who takes an interest in the boy's future and tries to help him in different ways.
Since I don't know the details of the 'ghost pony story', I can't say for sure who the main characters are. But it's likely that the ghost pony itself is one of the main characters.
Most likely, the pony itself is a main character. It could be a unique pony with special skills or a strong will.
I'm not sure exactly, but probably there are some cute little ponies. Maybe a pony named Star who is very brave.
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.
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.
There might be a wizard or a magical creature who causes the transformation. This character would play a significant role as they are the catalyst for the whole story. For instance, if it's a fairy, she might have her own motives for turning the boy into a bride, like teaching him a lesson about vanity or pride.