Richard Grayson was born a circus acrobat. Dick spent his childhood in the circus in "The Flying Graysons" an acrobat team including John Grayson (Dick's dad), Mary Grayson (Dick's mom), and Dick. They were a very happy family until the ringmaster did'nt pay off debt to Tony Zucco, a criminal leader. In turn, Tony killed Dick's parents. In the audiance watching was Bruce Wayne (Batman in his secret identdy). To Bruce their deaths reminded him of his parents deaths. Bruce payed for Dick's parents funeral, then adopted the boy. As we all know if you live with Bruce Wayne you'll eventually figure out his secret: he's Batman. Dick discovered this, so he made him his sidekick. Robin.
Dick later quit from the dynamic duo and became his own hero- Nightwing. He was replaced by Jason Todd.