Question marks in the mind of the listener. The Principle of Character Believable and recognisable. Purpose within the plot. Characters have to have function. Character has to be consistent with function.
Characters have to be intentional.
Start with a stereotype to ensure rapid recognition, then twist the stereotype. Challenge the homily that there is nothing new under the sun by making it new under the moon. Give each character a dominant physical or behavioural characteristic. Make the dominant characteristic purposeful. Make it extreme.