(SPOILERS: X-Men, Usual Suspects, Babel, Thelma and Louise)
All structural theories pretty much dictate that there can be only one main character. One character’s goal drives the story forward and provides the structure for your script.
“But wait,” you might be saying, “what about ensemble movies? What about movies with multiple story lines?”
One main character.
Even in a movie about a group, there will be one character whose goal is driving the story forward. And even in a movie with multiple story lines, there will be one character whose story provides structure to the whole affair. Let’s look at some examples.
X-Men: The X-men is a classic ensemble movie. It’s about a group of good mutants led by Professor X battling a group of bad mutants led by Magneto. But there is one character whose goal provides the structure for the story: Wolverine.
The main tension of the story is, “Can Wolverine protect Rogue?” That question is asked when Wolverine encounters Rogue in Canada and they are attacked by Sabertooth who was sent to kidnap Rogue (the Catalyst). The act one break is when Wolverine makes his deal to team up with the X-men to try to discover Magneto’s plans. The midpoint is Wolverine promising to watch out for Rogue if she stays with the X-men. The act two break is when Professor X is incapacitated, eliminating Wolverine's main hope of finding the kidnapped Rogue. And the resolution is when Wolverine (along with the other X-men) rescue Rogue at the Statue of Liberty.
The entire group participates in much of the story, but it is Wolverine who has assumed the roll of mentor to Rogue and it is Wolverine who is most deeply committed to the goal of saving her. That’s what drives the story. If you are going to write an ensemble story, pick one member of the ensemble to be the most committed to the goal and structure your script around that character.
Babel: Babel contains four main story lines – Brad Pitt as an American husband and father in Afghanistan trying to get aid for his wife who has been shot; the kids who pulled the trigger while fooling around with a gun; the nanny in California who takes her charges to Mexico; and the story of the teenage girl in Japan. The four stories are tied together thematically and by a few plot connections, but each is distinct.
Each of those story lines has its own main character. But Brad Pitt’s character is the main character of the entire movie. The movie is structured around his character’s journey. It is his character who has the problem at the catalyst (when his wife gets shot). The main tension is “Can he get help for his wife.” And the movie is dramatically finished when that tension is resolved. When you’re telling a story with multiple story lines, you should pick one to be the primary story that structures the movie. The main character of that story is the main character of the movie. (Note: you could create a viable movie structured around any one of those four storylines. But the filmmakers of Babel picked Pitt’s character.)
Now let’s get more complex!
The Usual Suspects: This is an ensemble film. So who is the main character? At first glance you might think it’s Verbal since he’s narrating the story. But just because a character is the viewpoint character, it does not mean he’s the main character. Verbal is not driving the story. We eventually learn that he is the instigator of the whole thing, but he is not the character with the problem that creates the structure of the film.
Next we might go to Agent Kujan since he’s the one trying to solve the murders. But he isn’t the primary driver of the story, either. The main story is in the flashback. Kujan is simply a framing device.
The actual main character is Dean Keaton. He’s the one who has the problem at the catalyst and he’s the one who provides the main tension.
And that main tension is, “Can Dean Keaton extricate himself from a life of crime?” Interestingly, we know the answer from the beginning of the movie. We see Dean Keaton get shot. Usual Suspects is a mystery and mysteries function differently than most narrative movies. They work more like Soduku puzzles. What we want to know is who killed Dean Keaton, which we eventually come to phrase as who is Keyser Soze. Unraveling the puzzle is what holds our interest. But the emotional and structural driver of the movie is Keaton’s desire to get out of his life of crime.
So, there can only be one main character. Except for the exceptions. You just knew there had to be exceptions, didn’t you? Well, they are extremely rare. In fact, I only know of one. And many people will argue that I’m wrong even about that one. The exception is:
Thelma and Louise: I think Thelma (Geena Davis) and Louise (Susan Sarandon) are two pieces of a single main character. Let’s look at how the movie breaks down structurally:
Catalyst: Thelma gets drunk and draws attention of a rapist.
Act One Break: Louise shoots the rapist and decides to run.
Midpoint: Thelma robs the liquor store, committing their first real crime.
Act Two Break: Louise stays on the phone too long, allowing the FBI to locate them.
Resolution: Thelma says “Let’s go” when they are facing the rim of the Grand Canyon, and Louise hits the gas.
See what happens there? The major beats alternate between the two characters. Louise gets the bigger beats, but then Thelma gets the character arc.
I don’t know if writer Callie Khouri did this consciously or not, but it makes sense if you imagine telling the story with just a single character. You could do it but you’d have a lot of scenes of a woman driving down a road not talking. You’d probably have to resort to voice over which would feel weak and lazy. By splitting the main character in two, the audience is able to enjoy hearing the women discuss their thoughts and feelings about the adventure they’re on. Usually when faced with this problem, writers give the main character a sidekick to talk to. Why Khouri instead chose to split the main character duties between two characters I don’t know, but it worked.
So unlike many writers and academics, I don’t believe that it is impossible to have two main characters. But it is very, very, very, very rare and I really wouldn’t advise trying it.