Reveal understandable motivations.
This principle relates to the agenda, “Reveal everyone’s personhood.”
If someone in the story seems to act in a way that seems more like a caricature than a person, you don’t need to accept that. Rely on curiosity rather than contradiction. If this person seems two-dimensional, don’t blame one of your friends for this portrayal. Instead, accept the mystery they’ve presented to you. What really motivates this person to act this way? Explore the question further, until you can understand and even sympathize with this person, even if her actions put her in direct conflict with your character.