on Helping Writers become Authors:

Using the Enneagram for character development can be a game-changer for crafting layered, believable characters.
This ancient personality typing system can offer deep insight into your characters’ core fears and motivations, which makes it a natural fit for building compelling internal arcs.
Because the Enneagram inherently emphasizes personal misconceptions (aka, the Lie the Character Believes), thematic Truths, and both Positive and Negative Change Arcs, it becomes an extremely intuitive tool for creating complex and realistic characters.
But there is a rub.