History
Callisto was the bodyguard to Moira MacTaggert, the Reichsminister of genetics, on an Earth where the Nazis had won World War Two. During a train journey, she and MacTaggert had their places exchanged with the Callisto and Moira MacTaggert of Earth-616 due to a dimensional portal created by Widget.[1]
The two women were taken into custody by WHO, where they rankled against their treatment. The Earth-597 version of Excalibur, Lightning Force were sent to rescue Callisto and Moira MacTaggert, and during the rescue attempt, Callisto overpowered and took hostage WHO's leader Brigadier Alysande Stuart, while Excalibur were apparently subdued by the Lightning Force. Excalibur turned the tables on their Nazi counterparts, however, Callisto was defeated by Meggan.[2]
Callisto, MacTaggert and Lightning Force were eventually returned to their own Earth, as it was thought by the authorities that they couldn't be tried for their crimes on another Earth. As they were returned to their own Earth, MacTaggert tried to sabotage the portal by throwing a grenade.[3]