What is Fitzgerald's purpose in detailing the characters' past lives and experiences?

Fitzgerald's purpose in detailing the characters' past lives and experiences is to provide context for their actions, motivations, and relationships in the present. By delving into their backgrounds, he enriches the characters' complexity and adds depth to the narrative, allowing readers to better understand the nuances of their behaviors and decisions. This also contributes to the exploration of themes such as class, identity, and the American Dream.