Sapphire Stagg was the daughter of industrialist Simon Stagg, and engaged to his employee Rex Mason. Sapphire met Rex Mason through his employment at her father's company, which led to an affair between the like-minded, passionate individuals.They kept their relationship a secret from her father until she told him that she was going with Rex to Chicago. It was then that Stagg decided to make Mason the test subject for his Metamorpho project to eliminate him from his daughter's life. His plan failed, however, as Sapphire still loved Rex after his transformation.