She was murdered by her adoptive brother, Billy, who would later become the supervillain known as Harm. Because of the manner of her death, Greta remained stuck on this plane of existence, a gateway between the living and the dead. In her first appearance, Secret was being held against her will by the DEO. Robin, Impulse, and Superboy helped her to escape, and were able to convince her to join their crimefighting team, "Young Justice," at the same time as Wonder Girl and Arrowette. Being incorpo