There’s more to a character than just a name and a description. You never want to write a screenplay for a specific actor because the chances that specific actor will play that part is minimal. However, you can imagine a certain actor playing each role because that will give you an idea how that particular character might look and behave.
Each character needs to be different somehow. Beyond different names, characters become more lifelike the same way strangers become more real. Once you get to know who they are, they’re no longer strangers but people. For example, walk into any public place and you’ll see lots of strangers who you may not care about other than seeing some people you’d like to meet and others you could safely ignore. That’s the way most screenplays treat characters. They describe the character and let you read their dialogue, but we never really get to know those characters because we never get to know their hopes, dreams, pain, and goals.
The next time you’re riding a bus, train, or plane, chances are good you’ll sit next to a stranger. If you talk to that stranger, you may learn their name. By talking some more, you may get to know some of their habits and quirks. However, what really bonds people to others is when we see someone in distress. If a stranger sitting next to you seems rude and arrogant, you might ignore that person. However, if you first learn that the stranger sitting next to you just proposed to his girlfriend at a ballpark and she told him no, suddenly that character’s rudeness totally makes sense. Once you realize the pain that person has experienced, you suddenly feel you know more about that person. The same thing happens when you reveal the pain behind your characters.
In “Thor: the Dark World,” Loki is a bad guy, but Thor needs his help anyway. When we see Loki’s pain at learning his mother has been killed, Loki’s motivation to help Thor becomes clear. Suddenly Loki ceases to become a one-dimensional character. By seeing his pain at his mother’s loss, Loki suddenly becomes a far more interesting character because we want to know how he’ll deal with this pain.
In “As Good As It Gets,” Jack Nicholson plays a despicable man who’s mean to everyone around him. However, when we see his lonely life and see how taking care of a dog brings joy to him, he no longer seems like a totally mean guy and suddenly becomes vulnerable. Knowing his vulnerability makes us actually care about him, even as he continues to spew insults and pain to those around him. If we never learn anything about his pain or his vulnerability, we never feel emotionally connected to him. No emotional connection to the characters means no interest in the story.
So if you want to make your characters come alive, show us their pain and vulnerabilities. Let us see them suffering. Let us see their dreams and how far away they really are from their dreams. That will make us see them as more than just actors and see them instead as real people we can actually care about. The moment we start caring about your characters, that’s the moment when your story comes alive for the audience as well.