Azalea was originally created by Draxum as a rebound incase the first four turtles didn't work (Mikey, Leo, Raph and Donnie) which they ended up being taken by Splinter. Draxum had four other turtles to transform into mutants, Azalea, Lily, Subject 7 and Subject 8.
Azalea was taken by Big Mama along with Lily to the Nexus and that's all she really knew as she grew up. It wasn't a fan of the Battle Nexus to begin with however Big Mama loved the fighting and violence and Azalea wanted to appease her. Eventually fighting once she was old enough, for praise and attention from Mama.
I might lore dump some more... but this is my first post, I wouldn't want to give too much away at the beginning. :,3