In an article entitled The Plot Thickens - 8 Ways to Bring Fiction to Life literary agent and author Noah Lukeman makes a very simple but useful point: One of the ways we get to know a character is by witnessing how other characters relate to them. Lukeman cites an example from The Godfather:
In the opening scene of ‘The Godfather,’ the character of Don Corleone is established without his doing or saying a thing. He sits behind a master desk, in a room of quietly devoted supporters, while across from him a man pleads for help and forgiveness. We get to know Don Corleone simply by watching THE WAY OTHERS TREAT HIM.
Think about that for a second. As a viewer, you intuitively understand that Corleone is a powerful, much-feared ruler, a kind of absolute monarch, from the way the people around him prostrate and humiliate themselves in front of him.
While writing, it’s easy to get stuck trying to figure out what a character should do in a scene in order to demonstrate who they are. Whereas sometimes a more effective way to show who they are, is to focus on what the other characters in the scene are doing in relation to them. Which is an important indicator of their position within the story world.
For example, in a scene introducing one of the main characters in a script I’m currently working on, we see a group of three young men speeding along in a car. The two guys in front are in their mid-twenties and the third, on the back seat, is about seventeen years old. The two older guys are euphoric, shouting and singing along to music. The younger guy keeps glancing nervously out of the rear window. The two men in front shower compliments on the younger guy for having kept his cool under pressure. They reassure him, tell him he can relax now. The kid laps it up, relieved.
From the older guys' attitude and words it becomes clear that the young guy has just been on his first serious criminal job in which he remained calm and professional while holding a gun to someone’s head for the first time. He’s now perceived as “initiated” by these veteran gangsters.
A scene like this, apart from setting a narrative in motion, also paints a picture of a character’s situation, of their station in life, their prospects and expectations, and so on. In this case, the younger guy’s inexperience, his ability to overcome fear, his willingness to use violence, his need for reassurance, his decision to embark on a career in crime … all of these character elements are implied by showing how the other two men relate to him, rather than showing the kid committing the crime itself.
Once you’re clear in your mind about what you want the audience (or reader) to know about a character, this is one way of portraying it. It’s a way of being able to show who your character is, while at the same time painting a picture of the situation or relationship they’re in. It simultaneously gives you room to expand on other characters too, as it’s them doing the work.
Of course, as with all screenwriting techniques, this is not a rule, but rather a possibility. It’s just one of many ways to think about how to introduce your character, and in screenwriting it pays to be aware of your options.