It’s essential for every story to have a cast of characters. There’s always the main character, or to be more technical, the main protagonist. Then there are the sidekicks, followed by peripheral characters and then chance encounters.
On the other side there’s the bad guy or technically the antagonist. Depending on the story, there may be more than one. The story may break down into the same bad guy sidekicks, followed by peripheral and chance bad guys.
As a writer, and depending on the genre, to create conflict which is what makes your story a story in the first place, you need a bit of both sides. How you break it down is entirely up to you, though certain genres usually abide by certain tropes to be categorized as that genre.
PROTAGONIST (GOOD GUY?)
Though this is slanted toward fiction, this can also apply toward autobiographies. After all, real life is full of good guys (you), sidekicks (your friends), lots of peripheral characters and of course, plenty of “bad” guys (the drama in your life). However I’ll be speaking mainly in terms of fiction so you non-fiction writers will have to adapt. Just keep in mind that an autobiography would be pretty dry without drama!
The premise of any story is the good guy, the driver of the story. This is the figure that the story is based upon, the purpose and center of the plot. Does this mean the person has to be good? Not at all. The “hero” can actually be a bad guy, someone despicable. That’s not the point. The point is, the character has to be the focus and the one you, the author, has to make sympathetic (or not so) for the reader. You might make them a real hero, a flawed hero, or someone despicable, but with some redeeming trait that the reader will care about so they continue reading. You have to give the reader a reason to root for (or against) the protagonist or there’s no point in the story, unless the whole point of the story is to set up the protagonist to fail in the first place. There are stories like that. I personally hate them, but that’s neither here nor there. It’s your story, and the protagonist is the focus of the plot, so good guy or not, that character is the reason for being there.
This person requires the most description and time devoted to character development. I wouldn’t dedicate whole chapters their inner feelings or past without action, but parse it out in palatable doses so not to bore the reader, unless the whole point of the story is a literary character study, a genre in itself. The past, such as flashbacks, can be done successfully in full chapters if there’s action involved, though as I’ve stated many times before, I’m not a big fan of long flashback scenes. Some people are, so if that’s your thing, it’s your call.
The sidekicks can be semi-main characters or just the guys or gals the protagonist kicks around and uses to move the plot along. It’s up to you. They usually get a lot of page time and help coalesce key plot elements.
They should get a decent description and modest character development. Whole chapters dedicated to their character development is a bit much, so keep that in mind (except the literary character study).
These are the chance encounters we run into every day. They require no further development than a basic description, maybe a name if you feel like it. That’s it. Case closed.
ANTAGONIST (BAD GUY?)
The bad guy (gal), or antagonist, is the other half of the equation. The bad guy or gal may not show up until halfway through the story, or even later, by name or physical presence, but his or her presence must felt right from the beginning. There has to be a reason for the story to take place.
Some authors spend a lot of real estate going into the bad guy’s head, either to justify why the bad guy is bad, or just because they’re literary and the hidden or overt premise of the book is a character study. If that’s your thing, fine. Whichever way you go, you need to justify what, where when why and how for the reader. Just make it interesting and believable. Try not to make the character cartoonish, unless that’s the purpose of the story. Too many times I’ve seen adventure and thriller stories portray the bad guy (or gal) as an extreme exaggeration, to the point of ridicule rather than simple “bigger is better.” Be sure not to skew the balance of description either by dedicating too much time to the bad guy and not enough to the good guy.
Some stories have more than one main bad guy, such as with sub-plots and red herrings. Just keep in mind not to go off on tangents.
As for bad guy sidekicks, they deserve as much attention as the good guy sidekicks. The same rules apply to peripheral bad guys as peripheral good guys.
TOO MANY CHARACTERS SPOIL THE PLOT
This is a common flaw of the omniscient point of view. These stories tend to have a cast of thousands like the Lord Of The Rings. Keep in mind that too many characters on either side leaves a muddled mess. By the end of the story, or even halfway through, the reader won’t be able to tell the difference between them and they lose their impact. While LOR was considered a classic, there were many who didn’t like it for that very reason. They couldn’t tell the difference between names and if it weren’t for the movies decades later and with the different faces and actors, they still wouldn’t know the difference.
I’ve read several thriller series of late that have that issue. They’re pseudo omniscient and have a huge cast, loosely held together by several main characters. The problem is that it’s hard to get invested in any one of them. While the story is fun to some degree, there’s no central character I really care about. I’m not invested in them.
THE CHOICE IS YOURS
Characters drive your story. The fewer and more memorable they are, the more likely your readers are going to want for more.
Just something to keep in mind.