Not much is known about Duane's life from before the apocalypse, but he presumably was a regular schoolboy. When the dead began walking, he and his parents took refuge in an abandoned house in King County, Georgia, which so happened to be next door to the Grimes household. By then, most of the townsfolk were dead or had left town altogether and the Jones family remained in the house for an unmentioned amount of time. During this period, Duane's mother Jenny was bitten by a zombie and turned, but Morgan was unable to bring himself to put her down and threw her out into the street where she remained wandering aimlessly.
Duane and his father Morgan met Rick Grimes some time later, finding him moping outside the house next door. Mistaking Rick for a walker, Duane smacked him in the head with a shovel, but luckily realised his error before killing him. When Rick woke up for the second time that day, Morgan and Duane introduced themselves and informed Rick about what had happened to the world. Rick remained with the Jones' for the next couple of days while he gathered up supplies for his journey to search for his missing family. Before leaving, he taught Duane how to properly use a gun and also left Morgan a walkie-talkie, regularly trying to contact him over the following days.
In the third season episode "Clear", Rick and Carl return to King County to find supplies to help them fortify the prison. When they arrive, they are confronted by a masked man who has laid booby traps all over town, but Rick shoots him and renders him unconscious. Rick removes the mask to find out his attacker is Morgan. Rick takes Morgan inside the store where he has made his base which is filled with weapons and supplies. Morgan has also scrawled various writings on the walls, including two words that stand out in large orange letters: "DUANE TURNED".
When Morgan wakes up, Rick asks him about what he's been doing since they parted ways. Morgan tells Rick the tragic story of how Duane died, how Morgan went to raid a cellar for food and Duane's undead mother approached him while he left the door open. Duane was unable to bring himself to shoot his mother and she lunged at him and bit him. It was only then that Morgan was able to finally put down his wife, but by then the damage had been done. Morgan apparently let his son reanimate but it is unknown whether he put him down or left him to wander as a walker.