Jack Heffron’s The Writer’s Idea Book, p.229, a prompt involves showing an aspect of a character’s personality that readers haven’t seen before in the novel. For example, if a character has been kind, considerate, and does everything right, show the opposite in a crucial scene.
Heffron talks about Tobias Wolff’s Mary, “In the Garden of the North American Martyrs” where his character is “very nervous about landing a job teaching history at a college”. She’s been “agreeable, despite feeling a bit bullied by the hiring committee. In her final interview…she attacks, recounting the atrocities committed by Iroquois Indians, describing in detail their methods of torture. The chairman of the committee tries to stop her speech, but she persists, switching to the tone of a righteous prophet.”
The character finally stands up for herself and the reader sees more depth in her. She presented “the surprising side to her personality” because she had been pushed to that point by old “hurts and losses that have nothing to do with the committee.”
I highly recommend Wolff’s story. I read it years ago. Thanks to Jack Heffron for not only reminding me of that story but giving a prompt for deepening our character with a surprising aspect of personality.