Copyright 2011 by Gary L. Pullman
In rhetoric, a warrant is an assumption or principle, often implicit, that connects evidence to a claim. For example, one might claim that women should be given the right to vote. Implicit in this claim is the principle that women, like men, deserve equal treatment under the law.
In fiction, there is an analogous relationship between one’s dominant, or cardinal, trait and the emotion that inspires this trait. One might say that the emotion is the cause of the trait and that the trait is expressed in the character’s behavior, even when a conflicting, but lesser, desire is present.
By implicitly (or explicitly) identifying the trait and the emotion that inspires it, a writer creates a character who is believable and realistic.
A few examples from Buffy the Vampire Slayer:
Buffy Summers feels compassion for others; therefore, she is driven, despite her desire to live a normal life, to accept her duty as a vampire slayer.
Rupert Giles feels guilt about his errant youth; therefore, he is driven to be responsible as an adult.
Angel feels remorse for his past misdeeds; therefore, he is driven to repent for them.
Xander Harris feels inconsequential; therefore, he is loyal to his friends.
Willow Rosenberg feels rejected by men; therefore she loves other women.
Cordelia Chase feels confident; therefore, she is honest--sometimes, brutally so.
By giving your own characters emotional warrants, as it were, that inspire their cardinal traits and expressing these traits in their behaviors, you, too, can make your own characters believable and realistic, adding, by their presence, greater verisimilitude to your story.
Note: Characters are very likely to have several or many other traits besides their cardinal trait. For example, Buffy is not only dutiful, but she is also immature, rebellious, independent, impulsive, protective, loyal, and courageous. However, her dominant trait is her dutifulness, and it is her dutifulness that is inspired by her compassion for others, causing her to sacrifice her own desire to live a normal life to protect and defend others, friends and strangers alike.