Obviously, Legion Haller is a main character. But there could also be other original characters created specifically for the fanfic. Maybe a sidekick who helps him in his adventures or an antagonist who tries to stop him.
Legion Haller is the central figure, of course. However, depending on the plot of the fanfic, other characters could emerge as main characters as well. For example, if the story is about a battle against an evil organization, the leaders of that organization could be considered main characters. And there could be characters that are important to Haller's personal growth, like a love interest or a family member that he discovers during the course of the story.
A great fanfic idea could be to write about Legion Haller in an alternate universe. For example, what if he had different powers or was part of a different society? You could also focus on his relationships with other characters, like his friends or enemies, and how they develop over time.
A group of veteran soldiers within the 433rd Legion could be main characters. They have seen many battles and their experiences and camaraderie shape the story as they face new threats.
Since I don't know the exact 'Black Legion Novel', it's hard to say for sure. However, in a story about a legion, there may be a military strategist who is crucial to the legion's success. There might also be an outsider who somehow gets involved with the Black Legion and changes their perspective or the legion's fate. For example, a spy from an opposing force who ends up sympathizing with the Black Legion.
The main characters in the 'legion of the black story' include Papa Emeritus, who is kind of like the face of the legion. There are also other unnamed or less - prominent characters that are part of the legion's hierarchy. They all contribute to the overall atmosphere and the development of the story. It's like a big family, but a very dark and mysterious one.
Alpharius is a major character. He is the primarch of the Alpha Legion and his actions and decisions drive a lot of the story. There are also various legionnaires who play important roles. Their loyalty to Alpharius and the Legion's overall goals are central to the plot.
I'm not sure specifically, but there might be a strong and noble leader, some brave soldiers, and perhaps a wise advisor.
I don't know for sure since I haven't read it. But it could be a leader of the legion who is strong - willed and has great leadership skills. There might also be a young and inexperienced character who grows throughout the story.
Since I haven't read the novel, I can't say for sure. But it might have a leader figure within the legion who is strong - willed and perhaps a bit of an anti - hero. There could also be some characters who are new to the legion and are still adjusting to their damned state.
Obviously, Laxus is one of the main characters. And then there's the original character (oc). The oc could be a mage with unique powers, or perhaps a non - mage with some other special abilities that make them stand out in the story.
The main character is, of course, the Original Character (OC). However, depending on the nature of the fanfic, other characters from the Ventus universe might also be main characters. For instance, if the OC has a mentor in the story, that mentor could be a significant main character.