Nightwing was once the first Robin. His origin starts when his parents are killed in a supposed accident when there tapeze wire snaps and since they perform without the safety of a net, they died. But, The young Dick Grayson (Soon to be Nightwing) hears the mob boss Tony Zucco arguing with the Circus Manager. The mob boss tells the manager that if he doesnt pay for protection from the mob then something might happen. After Dick's parents die, he is about to go to the police and tell them his knowledge, but before he could do that he is confronted by Batman. Batman tells him that if he goes to the police and reveals his knowledge it will eventually lead to his death. so Batman told him that they could work together. From this, Robin "The boy Wonder" was born.
Over the Years...
After a few years working along side of the caped crusader an incident with Two-Face made Robin to leave for a while due to a near death experience.