on Live Write Thrive:
Creating a cast of characters is a challenge for novelists. It’s a balance. You need just the right number of characters in just the right roles, and if you have too many, it’s clutter. Too few and your story is narrow and skimpy, possibly not reflecting real life. A protagonist that has no friends, doesn’t engage with coworkers, never talks to family, and doesn’t really go anywhere other than one or two locales (home, coffee shop, office) isn’t a believable character.
This is where secondary characters come into play. They require just as much forethought in their creation as primary characters.