Everyone intrinsically understands that the main characters have goals and motivations. But what about secondary character?
Ignore this being about fiction. Every person has some sort of goal or internal desire. Their lives might not be the stuff of Broadway musicals, but it is important to them and in his or her own way everyone has a complex existence. No matter how small a role a character in your story plays they must have some external driving force. Obviously you don't have time or care to delve into everyone that crops up in your pages, but, secondary characters who spend any amount of time interacting with the main character should have some goals and motivations both in line with and against your main character. We might not get to see all the complexities and nuances of their lives, but it should be at least alluded to that there is more behind the curtain. Show us that they have private dramas.
Motivations should not be stero-typical. The friend might be loyal, but, just like in real life, that loyalty isn't without bounds. A secondary character isn't just someone for the protagonist to talk to or the antagonist to plot with, a good secondary character will have driving reasons beyond just being helpful. However, you don't want the secondary character to overtake the story. Just like supporting actors can't upstage the star, a secondary character needs to be interesting without taking too much attention away from the protagonist.
A secondary character can be an agent of change for your protagonist. I don't know about you, but in some ways I interact a little differently with everyone I run across depending on who they are. For example, I act differently with my boss than I do with my Junior League friends, and I act differently with them than I would with my closest childhood friend. The same is true for your protagonist. In this way we are able to more intimately view the protagonist because we see how they interact with characters that are more complex. Everything rackets up a level.
The final thing that really interests me as a writer when working on secondary characters is the fact that no one is fully good nor fully evil and for the most part people want to do good or at least live up to their belief systems.
Secondary characters can be mentors, friends, friends of villains, neighbors, owners of a local store the protagonist frequents, family members or anyone really. Giving them lives of their own gives you plenty of fodder for sub-plots and themes as well as gives the protagonist a more robust life (by making those in his or her life more robust).
Some of my favorite secondary characters are:
- Obi Wan Kenobi (Star Wars)
- Sir Walter Elliot (Jane Austen’s Persuasion)
- Alaris (Jacqueline Carey's Kushiel's Dart series--actually she has many great secondary characters)
- Hermione Granger (Harry Potter series)
- Soup Nazi (Seinfield)