When the main character comes into deep conflict -- usually near the crisis of the story-- we normally see an irresistable force and an immovable object. That's what makes the crisis strong. In the resolution, one side will change; the other will normally remain steadfast. Each side gets a theme.
E.g.
Top story (this describes the situation and the conflicting goals of the characters):
When an unplanned pregnancy means another baby on the way, John desperately needs a promotion but his boss Chanelle is a terrible bully. Can John overcome his fear of Chanelle to present his demand?
When John comes into the office, Chanelle knows exactly what he wants. And what she wants is another chance to see the nervous little maggot squirm.
Bottom story (this describes why the characters are bound in conflict, and what their deepest motives are):
When John was five he contracted pneumonia and his left lung collapsed. Forever after, his mother mollycoddled him, denying him sport or playing outside with friends. John's father largely ignored him and John has arranged his life so that bossy women will tell him what he can and cannot do. His ruling passion is dependance.
Chanelle's alcoholic father was killed in a pedestrian accident when she was eight. Chanelle has pulled herself up into successful womanhood by her own bootstraps, but is filled with such a rage at her father that sees all men as weak and pathetic. She preferentially hires grovelling men, and enjoys punishing them. Her ruling passion is scorn.
How it might play:
John wants a promotion, but what he needs is self-respect. Chanelle wants to humiliate John but what she needs is to get over her abandonment issues. John is stuck between a bossy, pregnant wife and a bossy, scornful boss. Chanelle is stuck humiliating John until she can see him differently. So we have an irresistable force and an immovable object.
John's strategy is to endure whatever Chanelle demands of him as pleasantly as possible. Chanelle's strategy is to humiliate John more and more until he abandons wanting anything but to please her.
As possible outcomes, John might kill himself (despair), leave Gracie to become Chanelle's plaything (submission), kill Gracie and Chanelle both (wrath), quit his job and sort out his marital problems (self-reliance), or get the promotion he wants but remain subject to his wife's demands (mixed triumph). Conversely, Chanelle might drive John to death (wrath), turn him into a quivering gimp (domination), lose her life (overconfidence), lose him as an employee (humiliation), or shock herself into sympathy (compassion).
So our themes might be expressed as:
John: When dependance meets scorn, it leads to {despair, submission, wrath, self-reliance, or mixed triumph}.
Chanelle: When scorn meets dependance it leads to {wrath, domination, over-confidence, humiliation or compassion}.
Obviously, one theme determines the other.
Which theme is best? That really depends on the story you want to tell. Which is most surprising? Which seems truest? Which fits your mood preferences (e.g. romantic, comedic, tragic, horrific)? Which has the best resolution of the biggest crisis?
