Two Nations Collide (Zuko x oc) water

This is a teenage girl name Luna. She is from the southern water tribe along with her little siblings. They take a long journey to help Aang with his Avatar training and help him restore balance to the world but a long the way she falls in love with the Fire Nation Prince. Luna thought she was just a waterbender but she learns she's also a firebender as well and she also learns that she is half Fire Nation citizen from and know about her firebending ability. But what would happen that the Fire Nation Prince was her best friend when she had visit the Fire Nation and that she is also half Fire Nation.

P.S I do not own any of the avatar characters I only own the OC in this book