Ah! I see. I was treating "sacrifice" like a theme, i.e. a general concept rather than a specific thing someone does. Now that you mention that, it makes a lot more sense.
I think my point, vis a vis the Main Character, was that it helps to know your frame of reference for the story going forward. If the Main Character is the idealistic leader of the group who brought them together to rob from the rich and give to the poor, that's very different from the Main Character being the ex-cop face of the group who couldn't give a crap about what's right or wrong so long as they get paid. Because I can tell you about the same battle, but if I pitch it with the Main Character on one side of the conflict or the other, suddenly the meaning of the story changes a great deal.
Remember the Crucial Element, which binds the OS and MC together. Once you pick an MC, and you define their Problem, you've now determined a relationship between that and the OS Problem. (Or the Symptom/Response, if we're talking about Steadfast MCs.)
So if you liked my last set of four steps, you'll love these! This was a four-step story premise I gave to my clients for them to summarize their project for me:
- What is the problem?
- What is the solution?
- At the start of the story, why can't the characters reach the solution?
- At the end of the story, why can they now reach it?
(That's for Success stories, btw. For Failure stories, swap steps 3 and 4: "At the beginning, why could they," and "At the end, why can't they anymore.")
So for Wall-E, we might describe it as such:
- The problem of the story is that humans have abandoned Earth, believing it to be permanently uninhabitable. Thanks to their "3-hour tour," they've become fat and immobile--metaphorically infants.
- The solution to the story is for humanity to reclaim its destiny and birthright as the inheritors of Earth, to stand up on their own two feet and bring back life to a dying planet.
- At the start of the story, humanity has been blinded and controlled by autonomous robots. They can't go back to Earth so long as they're happy and content with their computer screens and food-in-a-cup.
- At the end of the story, the captain releases himself from AUTO's physical and psychological control. Dave and Mary release themselves from their screens and discover the beauty of the Axiom--and maybe each other?
My goal with this kind of premise is to establish the beginning of the story, the end of the story, and the steps needed to get from part A to part B. I think the "argument" of the story rests a great deal on those four parts.
Like, let's dig up the old chestnut: I cruise by the local used car lot, and I see a car I want, but it's too expensive for me. 1. I want to buy the car, but I don't have enough money. I know what needs to happen if I want the car: 2. I scrounge up the money and give it to the dealer. It's in 3 and 4 that suddenly we get huge variations in what the story's "about." Why can't I buy the car at the start? Is it because I'd have to sell all of my things, and I'm too materialistic? Is it that I'd have to rob banks to get the money, and I don't have the courage? Is it because I'd have to go to the blood bank and/or the sperm bank, and I'm afraid of needles/too shy to admit to the hot receptionist that I want to donate sperm? Whichever you pick, now you know what you need the story to be "about" to get to step 4. I have to go through a series of events to become less materialistic, or more courageous, or overcome my phobia or shyness.
Maybe that helps?