by Deren Hansen
Deepening Your Character's Needs," on the QueryTracker Blog. She described Maslow's hierarchy of needs, which range from the basic (like food) to the esoteric (like morality), and how characters are more realistic and more compelling if their behavior is driven by needs from more than one place in the hierarchy.
But it reveals a great deal about a character if and when they violate a lower-level need in favor of a higher level need. For example, someone may place themselves in danger (violating their need for safety) if by doing so they can save a loved one (satisfying their need for love and belonging).
In order to get away with violating your reader's common sense about the hierarchy of needs, you must establish the character's overriding need before they act against expectations.
Deren blogs daily at The Laws of Making.