No one knows anything much about Nightingale's past, not least herself.
She was (according to the graphic novel Memories) rescued by Foxbat from being attacked by Groundquaker. After discovering that she too had mystic powers, Stanly Hamilton decided to train her how to control them. Now, whenever she needs to use her powers to their full extent, she need only chant the words mesira estinos juu. Only one persion knows what they mean, and he isn't letting on.
Nightingale is one of the most powerful of Teen-Righteous. She is powerfully psychic, as well as being able to use various other mystic powers, such as levitation, and the ability to walk through solid objects by generating portals.
Originally only supported by Foxbat, and later by Starling, Nightingale is assisted by the other members of Teen-Righteous (although, she doesn't get along with all of them).
Although she faces every enemy the rest of the team does, Gripha, Issarra and Sampha seem to have developed a particular hatred of her.
Rabbit was one of the founding members of the League of Righteousness's Junior Squad, usually known as Teen-Righteous.