Okay, my characters, Piper and Jai'kar, are twins who bend opposing elements. Piper is a firebender, while Jai'kar is a waterbender. They both have black hair, but Piper has golden eyes, while Jai'kar possesses silver ones. Piper wears her hair shorter than most girls, preferring the ease of taking care of it over the style. Her brother wears his hair a little longer, just long enough for him to have a warrior's wolf tail. As twins, both of them are 17 years old, and have been all over the world. Their parents passed away when they were young, so they never had anything to tie them down. Both could be considered master benders, or close to it.
Piper learned firebending from the Sun Warriors, having stumbled upon their ruins by accident. Ironically, it was Jai'kar who performed the dance with her, being the only Waterbender to ever do so. While there, she also learned an amazing secret. The dragons were being repopulated by Rin and Shaw. That's where she obtained her mount and friend, Ignus, an adolescent, white dragon. After her training, they flew on Ignus to the Southern Water Tribe.
Jai'kar learned waterbending from the Chief, who took a great interest in his abilities and talent. To the old man, Jai'kar was like the son he never had, which resulted in Jai'kar learning pretty much all of the Chief's waterbending secrets. They remained there for a lot longer than they had in the Fire Nation before moving on and just wandering from place to place.
Ignus:
**I figured either Rin or Shaw should be female. It's never said in the show, but I think it would be sad for them to die out. It's not like the sky bison, where there's only one left. And I hope you don't mind my characters.**