In "Run for Your Life," a great page turner, James Patterson describes his main character know as "the Teacher" as a person determined to make his mark in the world by seeking revenge for childhood adversities. Caught up in his parents' bad divorce, he was separated from his brother (who stayed with their dad) and then raised in a bastion of privilege as his mother married a super wealthy man. The Teacher had nothing to do with his brother thereafter, never bothering to contact him in later life. Being the narcissist he was, the Teacher cared only for himself. One day, now an adult, the Teacher returned to his apartment to drop off his luggage and discovered the remains of his brother who had "blown his brains out." The Teacher then resolved to "get back at the people" allegedly responsible for messing up his brother's life. And so he lethally targeted people of privilege and became a one man walking crime wave in Manhattan.
The character and story of the Teacher is gripping. The weakness comes when Patterson turns psychologist and attributes "psychopathic" behavior to childhood hardship.
The human mind tries to make sense of experience. And that means dwelling on the "whys" of behavior to identify "causes". Patterson falls prey to this need to explain why. In my view, what he comes up with is a real stretch. His explanation results in an unnecessary diversion from the plot and contributes nothing to his portrayal of the main character.