I've been thinking about the difference between major characters and minor characters. How do you define who is a major character and who isn't? Is it solely on the basis of who has a POV? That doesn't seem inclusive enough to me for Born of this Soil. While I have four POV characters, there are others who are important to the plot, and some of them don't even appear "on camera" all that often.
Serrace barely appears at all until the end and has no POV of her own, but she is pivotal to the plot. Without her and the actions she is taking/wants to take, the story could not take place at all. Does this make her a major character? Another character plays an important role, and needs to be there for the story to continue, but he's mentioned in no more than three scenes in the entire book. What he does is important, but he could be anybody at all and the story wouldn't care.
I think, for me, that's what makes someone a major character: when the content of their character is, itself, what makes them important. No one else could be slotted into Serrace's position. It is her life events and her goals which make her important. She's a major character, despite the low number of her appearances. She is mentioned often, the other characters refer to what she's doing and what she's trying to accomplish. Some, in fact, revolve around her and her goals.
However, I try to fit characters into realistic situations, with realistic motives. Which means that who they are always plays a role to some degree. Rando, who I said could be anyone, still has ties to what he's doing that extend from his life. He does what he does because he has a reason, but I would never call him a major character. Readers probably won't even remember his name.
Lucel does what he does because of his life, his beliefs and youthful arrogance, and he pays for it hard. But does that make him a major character? While some of his actions matter to the story, the consequences are only relevant in how they affect the emotional outlooks of other characters.
The plot does not care who gets put in his situation, but the other characters do. I think of him as a minor character. So, I think that minor characters are those who affect the story, but not the plot and major characters are those who impact both the plot and the story. If that makes any sense.
What makes you consider someone a main character? Do they have to have a POV?