The Importance of Secondary Characters
Make sure that the names of your characters are different enough that your readers don't get them confused. Names beginning with the same letters, sounds, or names that have the same amount of consonants — Katie and Kathy, Susie and Sarah — can create confusion for a reader.
It's true, the major characters deserve and will require most of the book's focus. They are the brides and the secondary characters are the brides-maids. However, this doesn't mean that the secondary characters require less attention in their development. A well-crafted cast of characters not only enhances the role of the main characters but adds layers of interest to the novel. Here are some of the reasons that secondary characters deserve respect:
Readers often fall in love with the main protagonists through the eyes, ears, and thoughts of the secondary characters. Human beings can have skewed views of their own strengths and weaknesses. Secondary characters can paint truer portraits of the protagonists than the protagonists themselves.
Characters are judged by the company they keep. Whom a main character allows close and whom she attempts to push away will tell the reader a lot about her moral compass.
People are problematic. Characters are tools in which to introduce problems/conflict into novels. And because secondary characters are not held to the same standards as the hero/heroine, the writer can give them less sympathetic and more outrageous traits.
Secondary characters are great compare-and-contrast tools. A well-developed secondary character will bring out the best and the worst in the main protagonists.
People talk. Dialogue is crucial to stories. Nothing can hurt a scene more than too much narrative. Creating a large cast of characters who know the right things to say and ask, and the wrong things to say and ask, will make a story come alive for the editors and the readers.
Bridesmaids become brides and groomsmen become grooms. Lots of series have been developed accidentally because a secondary character grabbed the hearts and imagination of the readers and editors.