The Shape Shifting Bender

Kazuki has been living in the mountains alone since her parents were killed by earth benders four years ago. She's sixteen now and well hunting with her pet Xiara she is surrounded by bandits who want to use her to find a mine in the mountains. When she refuses they try to kill her, and before she could react two brothers, their sister, and their uncle swoop in and save her. The odd thing about this family is that they each bend a different element and they are on a search for the avatar sent by their oldest brother who just so happens to be the fire lord.