Who is Juni from My Bloody Life: The Making of a Latin King and what is their importance?

Juni was like a younger brother to Reymundo, and he loved to spend the night at Juni's house. He never understood, however, why Juni, who had a stable, loving home life, was infatuated with the violence of gangbanging. Although Juni was not a gang member, he foolishly flashed the King sign at a passing car one day. The Cobras in the car opened fire, and Juni bled to death in Reymundo's arms.