The Thematic Apperception Test (TAT) is commonly used for assessing motives.
Instead, a narrator blessed with the gift of gab and a nearly divine omniscience guided us through the characters' lives, assessing motives, assigning interpretations and neatly explaining all the coincidences that made up the complex pattern of their fates.
Dean himself has written two books assessing the identity and motives of Deep Throat, both of which were proven embarrassingly wrong in light of the recent revelation of Felt's role.
The interpersonal circle or interpersonal circumplex is a model for conceptualizing, organizing, and assessing interpersonal behavior, traits, and motives (Wiggins, 2003).
But Ms. Schiff seems to have inhaled everything there is to know about Cleopatra and her times, and she uses her authoritative knowledge of the era - and her instinctive understanding of her central players - to assess shrewdly probable and possible motives and outcomes.