Once upon a time, I took a course in playwriting. I got a lot out of that course, but one thing in particular that stuck with me was the exhortation to stick with two characters, the two that the play is about. Add other characters only as they are necessary.
Obviously, this is more a thing about plays than any other medium; you don’t want a cast of thousands on your stage, because actors are troublesome and take up space and demand payment. But it does apply to a degree to any story.
Many of the best stories in Western culture are, at their core, about two people, and the effect one has on the other. Other characters come in and out, complicating the situation or allowing the writer to externalize some of the protagonist’s internal processes or otherwise serving the story of the two main characters.
And then there are the stories that aren’t like this: ensemble pieces, like many TV shows. There’s something really compelling, in a serial drama, about rotating the main characters and giving everyone some time to start off this way, get their peripeteia, and come out changed.
