Why should you even bother to have one main character? Can't you just write a story, stuff a bunch of point-of-views (POVs) in from a bunch of main characters and get on with it?
You cannot have several main characters and expect the reader to get on with their life without confusion with your book. This is where a FOCUS Character (coined by me) comes in. Even if you do have a bunch of main characters switching back and forth between chapters, in the end, only one of the characters is actually the key to driving your story.
Take for example, Carla Buckley's "Invisible" (which is amazing, you should read it).
Here is the blurb taken from Amazon:
"Growing up, Dana Carlson and her older sister, Julie, are inseparable—Dana the impulsive one, Julie calmer and more nurturing. But then a devastating secret compels Dana to flee from home, not to see or speak to her sister for sixteen years.
When she receives the news that Julie is seriously ill, Dana knows that she must return to their hometown of Black Bear, Minnesota, to try and save her sister. Yet she arrives too late, only to discover that Black Bear has changed, and so have the people in it.
Julie has left behind a shattered teenage daughter, Peyton, and a mystery—what killed Julie may be killing others, too. Why is no one talking about it? Dana struggles to uncover the truth, but no one wants to hear it, including Peyton, who can’t forgive her aunt’s years-long absence. Dana had left to protect her own secrets, but Black Bear has a secret of its own—one that could tear apart Dana’s life, her family, and the whole town." (Amazon.com: Invisible: A Novel).
Although the chapters switch back and forth between Dana and Peyton, I soon came to realize that though the novel seems to be about Dana, it is actually about Peyton. Peyton is the focus character here (though others may say otherwise).
So, despite the fact that Carla Buckley has two main characters, only one of them is the actual focus, the actual drive for the story. If you read the book you might realize, Peyton's story can happen with Dana as a secondary character. BUT, Dana's story cannot happen without Peyton because Peyton drives the story.
If you're someone like Carla Buckley who has more than one main character, it's important to remember that the focus character is only one. If you don't focus, your story would look like it is all over the place and it's so incredibly hard to keep up with four strong main characters each with a super strong background and super intensive focus.
Main Characters are the main players in your story. They are the actors in the spotlight reading the script and acting out the scenes.
A Focus Character is the one main character that is essential for driving your story forward. Without the focus character, there would be no story. Not only are they in the spotlight but they are the directors and script writers. There can be several main characters, up to five (check this article for more on main character numbers) but only ONE focus character.
It is important not to confuse your reader.
Keep this in mind, fellow writers.
Happy writing! :D