Far be it to us to send you running in the direction of another blog, but you should really check out this interview with "Gentleman Bastards" author Scott Lynch at Mythic Scribes. The majority of the interview is concerned with writing about secondary characters.
Here's a snip, but be sure to check out the entire piece. Nice work! We can safely say that your novels have a balance of in-depth main and secondary, then background characters, all receiving their due page (screen) time. When planning (or writing/editing), how do you get that balance humming? The magic, I think, lies in the editing process… first I tend to ensure that I simply have the necessary secondary characters in place to serve their story functions. Then, during my assorted editing passes, I try to polish them up, wipe out boring or cliched dialogue, and somehow set them apart from their surroundings and from similar characters, elsewhere in the story and in stories like it. It’s no different than cleaning up any other aspect of my prose, really.Look for Scott's new book, The Republic of Thieves, in October!