1. The Story Spine is SINGULAR
Every plotline can only have ONE Story Spine. The main plot must revolve around your protagonist facing ONE problem and pursuing ONE goal. This is how you make a story strong, clear, and easy for an audience to follow. Your body works because it has only one spine. If you had more, you would be a disjointed mess. One of the best pieces of advice on writing I have ever receiving was that key to writing a great script is to create “a simple story with complex characters.” Having a strong, singular spine is the method by which one achieves this.
One of the surest ways to turn a story into a dense, complicated, hard to follow mess is to try to force your protagonist engaged in multiple, competing lines of action at the same time. You can't do two things at once. Don't try to give your protagonist two separate plot problems or two simultaneous goals. Don't have your hard-boiled cop be trying to take down the mafia and catch a serial killer. You can't have your medieval warrior struggle through the entire film to to both kill the dragon threatening his town and fight off the invading English Army. One might think that adding a second set of problems and goals would increase audience excitement just by the fact that there is more going on at once. In truth, the result is the opposite. Instead of increasing the excitement, it spreads the excitement thin. Story #1 winds up gets sapped of its energy and momentum every time it gets put on the shelf to change gears to Story #2, and vice versa. Meanwhile, both stories will suffer from underdevelopment in both plot and character since they simply do not have the time for it since they are forced to share their screen time with one or more other stories. Focus your main plot on a single problem, a single goal, and a single path of action. Save Story #2 for your next script.
This singularity also applies to each of the five elements in the Spine. There should only be one Main Story Conflict. Remember those two movies in the Batman franchise directed by Joel Schumacher, Batman Forever & Batman & Robin? Terrible, weren't they? The story was all over the place. The conflict was weak. This is because in each movie, instead of create a strong, singular villain for Batman to face off with, there were two. Two villains, both given equal weight. The story was split. Two villains also gave Batman two different goals- and the entire story suffered for it. Had the writers chosen to make one villain the head villain, and the other one the subservient henchman of the other, the stories could have been saved since there would still be only ONE main conflict that the both of them were a part of (as seen in many action movies where there is a strong villain and a loyal henchman).
As with Stakes, there is some flexibility in the singularity rule. Multiple things can contribute to Stakes, but it is always best if these things are all in some way related, and like I mentioned with the villains, there should be ONE thing contributing to the stakes that stands out as the biggest and most important.
2. For every plot, a Spine must be
Okay, you might be saying to me right now, 'Wait a minute. I've seen lots of movies where the protagonist has more than one goal. I've seen warriors who are both trying to kill the dragon and marry the princess. I've seen detectives who are not only trying to find the killer, but also fix their family problems. I've seen movies where the hero fights aliens AND tries to overcome his alcoholism.'
Now we've come upon the distinction between main plot and subplot. What I said before is that every PLOTLINE can have only one spine. Your subplots are separate plotlines. And in order for your subplots to be strong and effective, they need their own Story Spine too. Your hero's main story goal may have to deal with slaying the dragon, but there also needs to be a problem, goal, path of action, conflict, and stakes involved in his separate romantic subplot involving the princess as well.
Subplots do a lot to help a story in general. They add depth and dimension to a story that would otherwise be too thin with the main plot alone. They give opportunities to develop your characters and theme in ways that might not be possible within the swiftly-moving action of the main plot. What is important is the ability to to tell if you have a singular main plot and subplot that supports it, or if you have two main plots that steal attention from each other (two main Story Spines instead of one).
Subplots are often described as “smaller” stories. However, subplots are usually more like interior stories. They most often deal with personal struggles and relationships, while the main plot is an exterior story (the main story on the surface), involving physical conflict and direct action. Nothing can have two exteriors, that just wouldn't work. But an exterior and an interior can co-exist in harmony.
The key to a good subplot is that it is separate from the main plot, yet at the same time connected. The subplot does not take away from the main plot, rather, it adds to it. There is a symbiotic relationship between the Story Spine and subplot spine. The actions that take place in one work to influence the other, thus the spines work together to help bring about each other's resolution. Here is a link to a good article that uses the movie Honey, I Shrunk the Kids to present this interaction (separate yet connected) between the spine of the main plot, and that of the subplot.
3. “STORY SPINE” means “PROTAGONIST SPINE”
Alright. I don't want to confuse you. Or seem like I'm contradicting myself. So, I'll try to express this the best way I can. First, I said that the Story Spine had to be singular. Then, I said that each subplot had its own singular story spine. But guess what? There are more spines. The protagonist has his/her spine to follow. But the other characters have spines too!.
Before things get too complicated, back up and take another look at my previous article. Notice that all five of the Spine's elements are described in terms of their relationship to the PROTAGONIST. The protagonist's problem, the goal the protagonist sets, the path of action the protagonist takes, the conflict that seeks to prevent the protagonist from his/her goal, the stakes the protagonist faces. The “Story Spine” is in fact the “protagonist character's spine”. The two terms are synonymous. It is because the traditional Western film narrative focuses its entire attention on the actions of a central protagonist, the protagonist's character spine and the spine of the story are one in the same.
But, notice that in films with well crafted characters, the protagonist is not the only one with a problem, goal, path, conflict, and stakes. Though the narrative pays them less attention, all important characters should have these elements in their lives as well. When writers on screencraft say that every character should have their own wants, needs, things they are after, what they mean is every character must possess their own, separate (and singular) CHARACTER SPINE. A character spine is the one thing that makes your supporting characters into dimensioned, active, true to life human beings - with their own lives and their own reasons to exist. Character spines are the difference between having an antagonist who is a snarling, clichéd cardboard cut-out, and one who is an active, flesh and blood human being (or whatever type of being your antagonist is). A character spine is the difference between your supporting characters just being living props that exist solely for the convenience to your protagonist, to having a world populated with motivated individuals who do what they do for good, strong reasons.
Let's look at one of the most famous antagonists, Darth Vader. What is his character spine? 1. Vader's Problem: A Rebel army threatens the Empire's dominance in the galaxy. 2. Vader's Goal: To find the location of the Rebel base and destroy their army for good. 3. Vader's Path of Action: Among other things, to capture Princess Leia and force her to give the location. 4. Vader's Conflict: Members of the Rebel Alliance are doing all they can to stop that from happening. 5. Vader's Stakes: If he succeeds, his power in the Universe will be solidified for good. If he fails, it might mean the Empire's complete destruction.
Like subplots, character spines should be both separate yet connected in some way to the spine of your protagonist. The spines of all your supporting characters must in some way work to either assist or conflict with the protagonist's spine. Otherwise, if they have nothing directly to do with the protagonist's spine (read: the MAIN STORY SPINE) why are these characters in the story?
Character spines can apply even to the smallest of characters - though this spine doesn't need to be developed to such a large degree. Say you have created a one-scene bit part of a surly file clerk whom your protagonist is trying to get an important file from. If you give the file clerk a character spine it could potentially turn an otherwise dull scene into something dramatic. Observe:
1. File Clerk's Problem: The protagonist is making him do something he does not want to. 2. Goal: get the protagonist to go away. 3. Path of Action: whatever strategies the file clerk chooses to get the protagonist to leave. 4. Conflict: The protagonist refuses to go away. 5. Stakes: If he fails, it means a whole mess of work he does not want to do, or possibly get him in trouble with his supervisors. The ensuing battle between the two conflicting character spines is what will make this scene entertaining.