From Arkham, Riddler told the story of his youth. Eddie Nigma was an only child and a mediocre student. No one had time for him or the answers to his questions. He learned to cheat while in school and ended up winning a prize being the fastest person to put a puzzle together. That only led to bullies.
The prize he won was a book on puzzles and trickery. With it, he found his calling. After school, he got a job as a delivery man and became a smalltime thief. That didn't challenge him so he began leaving riddles and clues at the scene of his crimes. The cops, led by Lt. Gordon, finally figured things out and found him. So did the Batman. Dumb luck saved him and he was able to escape.
No one wanted to work with him on his next score until he was mugged by two girls in costume. They joined on with him as Echo and Query. A crossword puzzle sent Batman and the police to one location, but they chose the wrong one. Riddler and his girls were ripping off an underwater vault. Though Batman intervened, Riddler made off with around $2 million.
The next heist had them stealing some one-of-a-kind music instruments. Batman was in on the ransom and took down Echo and Query. He nabbed the Riddler at an opera.
Nigma realized there was no one behind the glass of his cell to hear the story he related and cracked.