Its hard to figure out what could be more messed up then murdering your own parents. Even John Steinbeck himself refers to her as a monster and a malformed soul. Although described as delicate and beautiful those who get close to this woman suffer the most as she manipulates and destroys anyone for her own entertainment and profit. Cathy is often referred to as the devil itself by critics as a part of the novel describes the way she eats as when (Cathy) swallowed, her tongue flicked around her lipsthey eyes were flat and the mouth with its small up-curve at the corners was carven lending Cathy a serpentine appearance. There doesnt seem to be any clear motivation behind Cathys actions other than she is just the embodiment of evil and this is an inescapable problem for some human beings.