Natasha Knight of Earth-One spent her early childhood living on the streets as a beggar until she was found and adopted by wealthy criminal Charles Knight. As an avid amateur astronomer, she accidentally was the victim of an errant radioactive laser that drained her of her pigment. When her father died, she and her step-brother Anton struck up a criminal career as Nocturna and the Night-Slayer, respectively. She'd plan the criminal heists and he'd execute them. However, when she became acquainted with Gotham City's Bruce Wayne and his alter ego of Batman, she forsook her crooked past and decided to lead a life in the straight and narrow. To that end, she desired adopting Wayne's ward and sidekick Jason "Robin" Todd. A clash with Night-Slayer ultimately led to both of their deaths as they were never seen again.
Lorna Dawn of Earth-Two was a secret service agent charged with guarding European scientist Dr. Joar Mahkent during an ocean voyage to the United States. They were interrupted by the intrusion of criminal Lanky Leeds who sought to exploit his success, however Joar's experimental cold gun went off. Blinded, Lorna was disoriented and later learned that a cold-themed villain known as the Icicle had plagued Gotham City. Enlisting the aid of Gotham City's Green Lantern, the pair tracked down Icicle and learned that he was actually Mahkent, assuming the civilian identity of Leeds to cover his tracks. When Icicle later returned, Dawn once more aided Lantern in defeating the criminal.
Both ladies were bewitching brunette beauties. One tied to the night, the other to the dawn. One to the dark side, the other to the light. And each found comfort in the arms of Gotham's Caped Crusaders, if only for a brief time.