- You may also be looking for Nightwing, the first Robin.
The second Robin, real name Tim Drake, replaced Dick Grayson.
Tim Drake was the son of Gotham City criminal Shifty Steven Drake, who was often a thug for the crimelord Two-Face. He had very little respect for his father, and often had to fend for himself. Around the age of 12, Tim began to idolize Gotham City hero Batman and placed newspaper clippings on his wall. After Batman left a batarang behind at a crime scene, Tim found it and began using it himself.
When his father double crossed Two-Face, he left Tim a note and a key to a Gotham City airport locker. This key was discovered by Two-Face's henchmen when they briefly kidnapped young Tim. Two-Face flipped his coin, and decided to execute Tim, but Batman showed up and rescued him.
Soon after, they discovered that Tim's father was killed outside of Gotham. With no place to go, Bruce Wayne adopted Tim and began to put him under his tutelage as the next Robin. (BGK: "Sins of the Father")
Almost immediately, Robin began working in the field. One of his first acts was helping Batman thwart the Joker's attempt to kill Gothamites with his Joker Gas during a New Years Eve celebration. (BGK: "Holiday Knights")
Tim’s costumed career was tainted, however. After Dick Grayson left Gotham for good to establish himself in another city (presumably Bludhaven), Robin patrolled alone one night. He thought he was saving a lone woman from thugs but instead, fell into a trap set by the Joker. For days at the old Arkham Asylum, the Joker systematically tortured Tim, learning secrets entrusted to Robin and then molded him into a crude version of himself. The Joker planned on using Drake to kill Batman but Drake turned and killed the Joker instead. A close friend of the Wayne family, Dr. Leslie Thompkins restored Drake to normal. However, Batman, feeling responsible for what happened, forbade Tim from donning the Robin costume ever again. Drake went out on his own and attempted several times to mend things with Batman only to fail.
Eventually, Tim quit the hero business and put his technological skills to use and became a top level communications engineer and started a family of his own. However, when he was held by the Joker, Tim was implanted with a microchip embedded with the Joker’s DNA. Over time, the Joker asserted himself and took control of Tim’s body.