Sometimes, an antagonist in the fanfiction, like a hunter who is out to expose or harm the changelings, can be a popular character as well. Their conflict with the main characters creates tension and excitement in the story.
In this type of fanfiction, Kakashi can be a really popular character. His intelligence and experience as a ninja can be explored further when dealing with the presence of changelings. He might be the one to figure out the secrets of the changelings first. Also, Sakura could be popular. Her growth as a ninja and her medical skills can play important roles when changelings are involved, like she could be the one to heal a changeling who has been injured in a unique way.
Queen Chrysalis is often a popular character. She has a strong presence and her villainous nature makes for interesting plotlines in fanfiction.
Probably the main characters from the original work tend to be popular in fanfiction. They are well - known and have established personalities that writers can build on.
A young changeling who is just coming of age could be a main character. They would be experiencing all the changes in the world from a fresh perspective and could be the catalyst for new ideas and relationships within the changeling community.
In addition to Twilight, there could be her pony friends. They might initially be confused or even scared when they discover Twilight's transformation into a changeling. Their reactions and how they come to accept or not accept her could be a major part of the story.
Most likely, the changelings would be the main characters. Since it's in the title, they are probably the focus. But it could also include some well - known MLP ponies like Twilight Sparkle or Fluttershy if the story involves the interaction between the changelings and the pony world.
I'm not entirely sure as I haven't read the specific 'The Changeling Novel'. But usually in such a novel, there would be the changeling character itself, perhaps a human who has been transformed. There might also be a mentor - like figure who helps the changeling understand their new state.
In many 'the changeling fanfic' stories, the main characters are likely to be changelings. They might be portrayed in different ways, like a young and naive changeling trying to find its place in the world, or an older, more experienced changeling who is trying to change the ways of their kind. Other possible main characters could be those who are affected by the changelings' actions, like a human village leader who has to deal with the presence of changelings near their village.
I think Rachel Morgan is often quite popular. Her strong will and unique powers make her a central figure in many fanfictions.
Megumi Fushiguro is popular as well. His cool and reserved demeanor, along with his powerful cursed technique, attracts a lot of fanfiction authors. They might write about his relationship with other characters, like his unspoken bond with Yuuji, or explore how he further hones his skills in different scenarios.