Treize's right-hand woman, Lady Une has a reputation as a fierce commander. Under his orders, she assassinated Vice Foreign Minister Darlian for knowing the truth about OZ, and ordered the assassination of his daughter Relena when she witnessed the murder. Her methods are brutal and ruthless, but effective; during a battle with the Gundams, she forced their surrender by threatening to destroy a colony with the Alliance's missile satellites. Afterward, Treize encouraged her to be more graceful. This apparently created a personality conflict, developing a new personality for her gentle, beatific attitude.
As Treize began to split with Romefeller, Lady Une was sent to free Duo, Wufei and the Gundam engineers from the Lunar Base but was shot by Chief Tsubarov. While recovering from her wound, Une had time to resolve her personal conflict. Shortly after the end of the war, Une was picked to become the leader of the new Earth government's peace watch group, Preventer. Her timely intervention saved the lives of both Relena and Mariemaia, revealing that Dekim's actions were not in line with Treize's philosophy. Once the rebellion ended, Lady Une decided to take care of Mariemaia, but kept her position as Preventer's head.