Another Avatar? (Zuko x OC)

Luli Zhen, one of the two remaining of the Air Nomads. 100 years ago, she and Aang were separated, Aang, ending up in an ocean near the Southern Water Tribe, and Luli frozen and contained in an ice and stone capsule. She fought the Fire Nation soldiers who tried to take her, chained, weak, and half dead, she had no other choice than freeze herself. That exact 100 years later, something snapped and she erupted from her capsule, same age, but there was something off, something far off. Her once pure snow hair shifted to and from a dull black. Her once dull green eyes shifted to and from a fiery red.
Lucky for her, her capsule broke at the perfect time, reuniting with her once best friend, Aang, also the Avatar.
It was extremely rare to have two Avatars at the same time. but of the same Tribe? Never.