The Character is The Story
In other words, every action from the protagonist/s moves the story forward to the end result. If you are creating a piece of life of a character, you are creating a story. Think of it this way...are you living your own story? The answer is yes, and the following is your story:
The throughline is the main objective of the character. It is the motive behind every action and every decision in the story. Some of the best movies ever written have throughlines for protagonists that stayed the same from inciting incident to end credits, and they either acheived their goal or didn't. See if you can recognize these...
And some throughlines are complex and involve a character's inner struggle. The character battles with more than one goal or purpose.
10 throughline examples:
slay the dragon/save the world
learn an incredible skill
Aristotle defined character as the sum of the individual's actions. The throughline supports the actions of the character. Therefore, to understand your character's throughline is to understand how to guide your story. Why? Because character is story!
William H. Macy visited my company's acting class and told us that the "throughline" was a b.s. tool that he never used. He exclaimed that he only focused on doing, not thinking, while he was creating a character. He told us that he did only what action was directly in front of him. He is an impulsive actor. His performances are generated organically, and his accent, posture, lines, costume, lighting, musical score, composition in the frame, and so on all contribute to his character. Good writers have provided the words and circumstance so that he can showcase his work at its finest. Write a good throughline of action so that the actors that play your parts don't have to think about it!
There's a law in psychology created by two Harvard professors that says,
"As problems seem larger, our ability to solve them declines as a result of fear or anxiety" - Yerkes-Dodson Law. So don't try to take on everything at once, and I'll try to keep things succinct.
Actors look at scripts in terms of actions and beats. Actions are miniature goals that are based on their relevancy to the throughline of the character.
Within a scene, there may be more than one action. Usually, in film, there are only one or two actions in a given scene. They are separated by markers called beats.
Therefore, it is your job as a writer to set up a goal for each character in the scene, and then present a new piece of information that changes that miniature goal. The new piece of information is a beat.
Example of a beat: The girlfriend says she is cheating, a tree falls on the main character's car, a new character is introduced, etc..
Examples of actions: beg a loved one's forgiveness, take what is rightfully mine, enlist a brother to join the cause, cheer up a depressed soul, convince a friend to take a big leap, put a jerk in their place, persuade a girl to love me, let a subordinate know who's boss, grab a celebrity's attention.
Notice that these examples have good action verbs and that they are in the present tense.
Notice that I threw in the words "me" and "mine". Use your own experience to give a voice to the character. Even if the character is a serial killer, you can pull from your past to make that character speak or act in a way that is unique. In order to avoid cliches and give the characters depth, either successfully put yourself in another person's shoes or use your own experiences to guide their existence.
Now, it's time to break down a scene...