A longtime family friend of Torbjörn Lindholm, Ziegler had pioneered a breakthrough in the field of applied nanobiology at a young age. The technology radically improved the treatment of life-threatening illnesses and injuries. It was this expertise that attracted the attention of Overwatch.

Because her parents had been taken by war, Ziegler was opposed to the organization's militaristic approach to keeping global peace. Ultimately, she recognized that Overwatch offered her the opportunity to save lives on a much larger scale. As Overwatch's head of medical research, Ziegler sought to leverage her work for healing in frontline crises. The result was the Valkyrie swift-response suit, which Ziegler herself piloted on many Overwatch missions.

Despite her contributions to Overwatch, she was often at odds with her superiors and the organization's overarching aims. Though she lent her brilliant mind to healing her comrades, Ziegler had dire concerns about the affairs of Blackwatch, specifically pertaining to Commander Reyes and his own medical support, Moira O’Deorain. When Overwatch dissolved, Ziegler sought distance from the agency and re-dedicated herself to helping those affected by war, caring for the broken and dispossessed in crisis areas around the world.