In life, we meet countless people who are secondary characters to our life story: our neighbours; our colleagues; the servers at our favourite coffee shop. These people don't exist solely to serve our life stories. They are their own entities. They have their own back stories, their own personalities, and their own actions, reactions, thoughts and feelings.
But our novels aren't real life, and often the importance of secondary characters are overlooked in the author's pursuit of the plot. They exist because they have to: you can't have your hero and heroine falling in love in the empty Scottish Highlands, after all.
When we're plodding along, committing our brilliant little stories to paper (or word processor), we often focus too much on the main characters and not enough on the secondary characters.
To the detriment of our finished books.
Why are Secondary Characters Important?
Main characters are the meat of your story. They are what everyone can't wait to dig into; they are what everyone congratulates the chef on. But you can't have a balanced dinner without the veg, starch, and cheesecake for dessert.
Secondary characters are like your side dishes. Boiled potatoes, steamed carrots and undressed lettuce are pretty forgettable. But scalloped potatoes with cheese, maple-glazed carrots and caesar salad with bacon, on the other hand ... well, you get my point.
(My apologies to the vegetarians reading this post, as an aside.)
Secondary characters need to be fleshed out. They need to have their own, individual voices, their own flaws and quirks, and their own back stories. They are what give your story vibrancy. And, more importantly, they help bring your hero and heroine to life, too. They are the catalysts that propel the actions, thoughts and feelings of your main characters.
Spoiler Alert ...
Take, for example, my Highland Loyalties series. Would anyone have cared about Ruth's violent and untimely death if she'd been only a stock character? An un-opinionated, impersonal maid who cleans out Lady Jane's chamber pot every morning would have earned very few tears when she's wrongly hanged for treason.
Or Tearlach (that's Scots for Charles, by the way). Would anyone have cared whether or not he survived the final battle with Baron D'Aubrey's men if he weren't the loyal, fatherly figure to Robbie MacGillivray, but instead was just the stand-in character that represented the Dunloch steward?
Secondary Characters Matter
As with real people, your secondary characters should be living, breathing entities. Memorable secondary characters are what make your readers care about the story as a whole. Spend time introducing them to your readers, spend time developing them into the multi-faceted gems they are. They deserve to be as much a part of your novel as your hero and heroine do.
And, if you serialize your novels, they can in turn become main characters themselves. Bonus!