The easiest way to write a bad screenplay is to start writing with no advance planning. This will guarantee you’ll write about 50 pages before running out of ideas. The simplest way to write a good screenplay is to plan your story in advance and one feature of story planning involves creating something from the hero’s past that haunts him or her in the present. Now the hero needs to work to fix this problem from the past.
There are two ways to explain this torment from the past. One way is to make this torment part of Act I and show this problem right up front. In “Cliffhanger,” the hero fails to save a woman and watches her plunge to her death. This traumatic event haunts him so he has to redeem himself later. In many superhero movies such as “Wonder Woman” or “Spiderman,” this traumatic past is part of the exposition. That’s where we learn that Wonder Woman watched her friends get killed by evil men or we learn that Spiderman’s parents died because he failed to take action to stop a mugger. From that point on, we understand the hero’s motivation to fix the pain from the past.
A second way to haunt the hero is to hide this traumatic event from the audience. Instead, this event shapes the hero’s actions and we’re left guessing at what happens until the end of Act IIa when the hero finally admits his or her problem. In “Die Hard,” we never get to witness the hero’s initial breakup with his wife, but we get to see him trying to get back together with her. Only when he’s alone in a restroom, pulling glass shards out of his feet and talking to the black police officer over the radio do we learn more about how the hero blames himself for being a jerk and not appreciating his wife. We still never witness the hero’s painful past, but now we have a better idea what happened.
In “Casablanca,” we know something’s bothering the hero, but we never fully understand it until near the end of Act IIb when a flashback shows the hero being stood up by the woman he loved. That caused him to become bitter and angry at her, which explains his behavior since the beginning of the movie.
So the two ways to introduce the pain from the hero’s past is to make it an early part of the story in Act I, or to hide it and only reveal it at the end of Act IIb. Whatever method you choose doesn’t matter so much as the haunted past is a crucial part of any story. Every hero needs to overcome a painful memory from the past. A story is about redeeming him or herself from this painful past.
In “Legally Blonde,” the hero’s painful past involves getting dumped by her boyfriend when she thought he was going to propose to her (Act I).
In “Harold and Maude,” the hero’s painful past involves learning his mother loved him more when she thought he was dead than when he was alive (Act IIb).
In most cases, putting the hero’s painful past in the beginning (Act I) lets the audience feel the trauma as the hero goes through it. However, sometimes it’s best to disguise the hero’s painful past and keep it a mystery. This can be effective when the hero’s motivation is a bit more of a mystery such as in “Casablanca.”
The key point is that your hero must suffer trauma from the past and the story is about overcoming this trauma to become a better person. Without this painful past, the hero has nothing to overcome. That’s why every hero needs a painful past to force him or her to deal with a painful situation and emerge a better person as a result.