The Women of Legend
Bette Kane grew up idolizing her older cousin, Kate Kane. When she discovered Kate was actually Batwoman, Bette took on the persona of DC Comics Flamebird and announced that she wanted to be her cousin's sidekick. Under Kate's tutelage, Bette has become a skilled martial artist, and the pairing has begun to make a name for itself.
(That's not really how it happened)