Edward Nigma discovered puzzles when he was a young boy, and he gradually incorporated them into his criminal career. Issue #2 of Justice by Alex Ross suggests that his father physically abused him, which left him with a compulsion to tell the truth (materializing through the telling of riddles), as well as a desire to prove his superiority by outwitting everyone around him
The Riddler's criminal modus operandi is so deeply ingrained into his personality that he is virtually powerless to stop himself from acting it out. He cannot simply kill his opponents when he has the upper hand; he has to put them in a deathtrap to see if he can devise a life and death intellectual challenge that the hero cannot solve and escape. However, unlike many of Batman's themed enemies, Riddler's compulsion is quite flexible, allowing him to commit any crime as long as he can describe it in a riddle or puzzle. He often has two female assistants, named Query and Echo. In Batman Secret Origins Special, Riddler proclaimed that he had four henchmen named "Mark, Mark, Mark, and Mark
Sometimes, he is shown to drive a "Riddlermobile," a green car with "???" on the license plate. A knockoff of the Batmobile. Riddler also often carries a trick question mark-shaped cane
