What is the main struggle in book Divergent?

In the book "Divergent", the main struggle revolves around the conflict between the protagonist, Beatrice "Tris" Prior, and the dystopian society she lives in. This society is divided into five factions, each representing a different virtue: Abnegation (selflessness), Amity (peacefulness), Candor (honesty), Dauntless (bravery), and Erudite (intelligence). Tris is born into Abnegation but feels drawn to Dauntless. When she takes the aptitude test, Tris is found to be Divergent, meaning she has traits that fit into multiple factions. This makes her a threat to the society's rigid social structure and she must choose between remaining in Abnegation or joining Dauntless.

Throughout the book, Tris faces various challenges and struggles. She must undergo the dangerous Dauntless initiation process and prove herself worthy of staying in the faction. She also discovers the existence of a rebel group called the Erudite who wants to overthrow the existing social order. Tris gets tangled in the conflict between the factions, and must make difficult choices to protect herself and her loved ones.

Ultimately, the main struggle in "Divergent" is between the individual's desire for freedom and self-expression and the oppressive forces of a totalitarian society. Tris' journey is a reflection of the human desire to break free from societal constraints and find one's own path.