The pilot of the Gundam Deathscythe, Duo is as jolly and happy-go-lucky as Gundam pilots get. He persists in offering his friendship to the initially hostile Heero, eventually winning his antisocial comrade's trust through sheer persistence. But despite his friendly nature, Duo earns his "God of Death" nickname when he takes on Alliance and OZ soldiers in battle.

Prior to Operation Meteor, Duo was part of the spacegoing salvage organization known as the Sweeper Group, and on Earth he is assisted by the Sweepers' seafaring kinsfolk. When there is a lull in the fighting, Duo happily returns to his salvage-merchant's trade. He is distinguished by his black wardrobe, his yard-long braided ponytail, and his minister's collar.

Duo Maxwell is an orphan of U.S. descent who was raised by the L2 colony's social services program. By the age of 15, he had already been employed in field operations and as a mechanic. Despite his hardships, Duo has a cheerful outlook. At times, he finds his friends overly serious and tries to teach them to relax and enjoy themselves.

Duo's light-heartedness, however, is not reflected in his fighting. As the pilot of the Deathscythe, he is a determined warrior willing to sacrifice anything for victory. His fighting ability combined with his gentle and humorous persona make Duo very popular.

The leader of the group, Solo, died of an epidemic that had been going around, in honor of Solo, Duo named himself Duo. When Duo got caught by the federation army, he was taken in by the Maxwell Church, which is how he got his last name. Duo had to steal a mobile suit to save the church, when he got back, the priest had died and Sister Helen was dying. The destruction of the Maxwell Church was called the Maxwell Church Tragedy. Duo snuck onto Dr. G's ship, and that is how he got to know him.