Irving was a henchman of Cameron Kaiser.
Facing a financial disaster, Kaiser decided to cash in insurance money by having the Joker wreck his brand new casino. He already redecorated it—from Camelot to Joker's Wild—to infuriate the Clown Prince of Crime; the only thing he needed now was to spring the Joker out of Arkham. Irving was presumably a bodyguard or like henchman of Cameron Kaiser, as he was entrusted with the plan to commit insurance fraud.
Irving infiltrated the Asylum as a guard in order to let Joker escape—though he had to do so without the Joker noticing it. He took advantage of a squabble that erupted between the Joker and other inmates over what to watch on TV by seizing the remote control and saying he will deciding, changing the channel to the evening news, which was announcing Kaiser's grand opening to set off the Joker and played it dumb, taking a feigning Joker to the sick bay, but "accidentally" leaving the doors open. The Joker called Irving a "maroon" for being so careless and fled to freedom, only for a smug Irving, who was actually seeing the clown escape from a short distance, to silently say to Joker "I know you are, but what am I?" for being naive to the intentional escape.
With the Joker on the loose, Irving returned to the casino to await further orders from his boss, Mr. Kaiser. He caught Batman sneaking around in Kaiser's office, but after a short fight the Dark Knight was able to get away by using a smoke pellet. Irving later delivered Batman to the basement under Kaiser's orders.