Supergirl

After discovering Krypton was about to explode, Kara's father Zor-L launched her as an infant to Earth in a ship at the same time that Kal-L's ship was launched. However, Kara's ship took a much longer journey, resulting in her arriving on Earth decades after her cousin.

Unlike Kal-L's ship which was designed for fast travel, Kara's "Symbioship" was designed to hold her in stasis during her development through the prolonged voyage. In addition, the ship's artificial intelligence ran a virtual reality program, allowing her to interact with life-like copies of her parents and fellow Kryptonians. By the time she landed on Earth, Kara was an adult woman in her early twenties.

Power Girl's existence was not revealed to the general public until years after her arrival on Earth-Two. Her cousin Clark and his wife Lois provided her with a family environment that aided her transition from the virtual reality she had experienced during her voyage to real life relationships. She came to regard her cousin and his wife as her "uncle" and "aunt" for raising her on Earth-Two despite being cousins by blood and marriage. Lois Lane-Kent stated that they regarded her as their daughter.

In her first recorded case, Kara assisted Justice Society members Flash and Wildcat in containing an artificially induced volcano that had erupted in Peking, China. She then joined them and other young heroes Robin and Star-Spangled Kid to form a Super Squad, along with active members of the Justice Society, to defeat Brain Wave and Per Degaton's scheme for world domination. Later, she was granted full membership when she took over Superman's vacated spot on the team roster.

Having been raised by the Symbioship with artificial Kryptonian life experiences, Power Girl had trouble fitting into life on Earth, but with the help of reporter Andrew Vinson, she eventually adopted the secret identity of computer programmer Karen Starr. She developed her knowledge in this field from treatment under Wonder Woman's purple ray on Paradise Island. Outside of the Justice Society, she developed a close friendship with Helena Wayne, the daughter of the Earth-Two Batman and Catwoman and was later a founding member of Infinity, Inc.