2. supporting characters
3. invisible characters
Major characters show up often in the story. Readers will care about them. Readers expect to find out what happens to them by the end of the book. Obviously, among your major characters, the first and most important one is your protagonist. No matter how many major characters you have, there should be only one protagonist.
Supporting characters may make a difference in the plot, but readers aren’t emotionally involved with them. They may cause a twist in the story, but they will not play a major role in shaping the story.
A supporting player does one or two things in the book and disappears. You may name supporting players and perhaps divulge a little bit of background, but they are not as important as major characters are.
Examples of a supporting character would be a man who discovers the body in a mystery, the crazy ex-girlfriend in a romance, or the guard of the Seat of Death in a science fiction book.
Don't overcrowd the book.
Characters should be individualized, but functional, like figures in a painting. Active characters make things happen. They react, but they are also proactive. When active characters keep trying to solve their problems and keep taking missteps, story tension mounts.
Passive characters let things happen to them. The protagonist should never be a passive character. Readers tend to like active characters, but it’s hard to have sympathy for characters who simply sit and wait for fate to overtake them.
One way to make supporting characters memorable is with the use of character tags or labels. Each of us makes an impression on those around us. Fair or not, we go through life sorted as sinner or saint, extrovert or egghead, nice or nasty.
Dominant impression is made up of four basic elements, gender, age, vocation, and manner.
When we describe anyone, we usually mention gender, this man, this woman, him, her. Age gets attention in terms of deviations from the norm of adulthood, as in little girl, boy, old man and teenager. Vocation is their occupation, what they do for a living.
Manner is an individual's personal bearing, their habitual stance, and style. Manner is what impresses you when you meet someone, what's going on inside the person. A character's manner gives you something predictable to use in your dialogue writing. You know the words they're likely to speak. To capture manner in your writing, you can use incidents, which convey the manner.
If you used only the dominant impression, the character will be a caricature, not a person. You need to flesh them out, to give them tags, traits, and relationships.
A tag is a label, which identifies a character and helps your readers distinguish one character from another.
The most important tag, of course, is a name. A useful character tag is giving readers some idea of the character's appearance. However, don’t describe them in detail. Let readers use their imagination. What readers imagine is always better than what you can describe.
Any item that strikes a distinctive note will do, such as habitual cigar between the teeth, a bushy mustache or a missing finger. A character tag is a mannerism such as rubbing the chin or an unruly laugh. A character who doodles when she talks, or who straightens anything near her, or one who smooths her hair constantly are all demonstrating mannerisms which help readers to tell them apart.
Attitude is another kind of character tag. Mary Poppins and her eternal cheeriness reflect an attitude just as Iron Man’s rampant ego does. Racism and sexism are attitudes too, as are nervousness, dissatisfaction, and deep-seated distrust. Supporting characters can be recalled by readers simply because they are odd or colorful. Strive not to use clichés as character tags. We’ve had enough of rumpled detectives in dirty trench coats, dumb blondes or computer guys with pocket protectors.
You won't develop these characters at all. They're what movie people call extras or atmosphere. These characters are in the background, only there to lend realism. After that, they disappear, forgotten. You keep background people in their place by not describing them at all, and not naming them, which renders them invisible.
"Chester handed the bellman his suitcase."
You don’t describe these invisible people because readers think anything you mention is important and they will try to remember it. If you describe and name every server, store clerk, and cab driver, readers will go crazy.