Double L's seemed to have significant roles in the lives of both Supermen. Each had a Lois Lane, Lana Lang, (A)Lex(ie) Luthor, Lewis Lang, Lora Lor-Van. There was also a Lori Lemaris, Lyla Lerrol, Lea Lindy and Liand-ly.
Today we dissect two women of strong will, although not typically mentioned in this list: Louise-L aka the Supergirl of 500,000 AD and Kara Zor-L aka Power Girl of the notional dimension of Asgard. They were a pair of blonde lasses who each aided their inspirations, Supergirl and Power Girl, in saving their respective Earths in the 20th century.
Louise-L was born in the 5020th century, a resident of the city of Hattan, formerly Manhattan. How she came to have superhuman powers like Kal-El and Kara Zor-El of the 20th century is unknown. Similarly, she had the same appearance as that of Kara, and also went by the alias of Supergirl. On Earth-One of her era, the environment was such that the mass of the planet had decreased, leaving a mostly molten core under an orange sun. This culmination of conditions left Louise severely depleted in abilities compared to her possible ancestress. When the criminal Tal Belok of her time aided his own ancestor Virgil Belasco of our time period by giving him technology to become Toxus. In order to combat this dastardly duo, she recruited Superman. Together, they were able to defeat both Toxus and Tal, trapping them each in the other's era.
However, Toxus was freed due to an explosion, and returned to the 20th century to wreak revenge. Having wiped out memory of her existence from Superman, she sought out a new ally in his Kryptonian kinfolk, Supergirl. On another occasion, she encountered Kal-L's cousin Power Girl, the counterpart to Supergirl. Louise-L remained in the 20th century, assuming her predecessor's secret identity of Linda Danvers in order to entertain some business associates of hers while trying to track down Toxus. Meanwhile, Kara aka the real Linda journeyed to the 500,000 AD to deal with Belok. Once both gals defeated their adversaries and returned them to their respective authorities, Louise-L wiped out all memories of her existence from Kara.
As for the Maiden of Might from the fabricated reality attached to Earth-Two, known as Asgard, she was originally just a soldier fighting alongside her fellow warriors against an impending invasion spurred on by a power mad Adolph Hitler. His intent was for the conflict to spill over into his world, leaving it destroyed as revenge for his decisive defeat during World War II. In order to aid the Asgardians, the visiting Justice Society of a post-Crisis composite Earth traveled to Earth-Two's dimension and merged with various heroes native to this pocket dimension. The heroine whom Power Girl became bore an uncanny resemblance to herself, and she would fight side-by-side with her fellow Socialites in this timeless dimension.
However, this version of Power Girl was soon freed from Asgard, and her role as well as that of her teammates during this Ragnaroth conflict there was assumed by members of the Abraxis dimension. As such, the Asgardian Power Girl lived on to fight another day,