Divergent
Four. A Divergent Collection

Two years before Beatrice Prior makes her choice, the sixteen-year-old son of Abnegation's faction leader does the same. Tobias's transfer to Dauntless is his chance to begin again. Newly renamed `Four' he discovers that initiation is only the beginning... Four must claim his place in the Dauntless hierarchy. And his decisions will affect future initiates as well as uncover secrets that could threaten his own future — and the future of the entire faction system.
Two years later, Four is poised to act but the course is still unclear. The first new initiate who jumps into the net might change all that. With her, the way to righting their world might become clear. With her, it might become possible to be Tobias once again.