“Death was all over him,” Parks wrote of Flávio, a severely asthmatic Brazilian boy, only 12, whose suffering he photographed. Parks was in Brazil for a Life-commissioned photo series, and his focus on Flávio not only illuminated poverty’s perils but told a story of deep empathy between photographer and subject. That empathy continued for many years afterward—a relationship caught and held by the camera. —C.J.F.