If you want people to love your book, don’t have cardboard cutouts for the secondary characters! Sometimes authors spend so much energy and wordage developing the main characters, they seem to be too tired to do much with the secondary characters. But they’re very important too. These minor people can add immense depth and passion to the story, showing the reader all sorts of facets about the man characters. Do they smile at servants and say “Thank you”? Do they gossip girlishly with a friend? Does he treat his favorite horse as if it were his best friend?
I’m not saying every placeholder character in the story needs a chapter of description from birth to this moment, but they do need a brief outline. Are they easy-going or uptight? Do they understand and approve of the main character? Can you make them fresh and distinctive in just a few lines of dialogue?
Besides, if this book proves popular, these secondary characters may become heroes and heroines in a later book in their own right.