I think Aang and Zuko discover the air benders that have evolved by going underground the have the power to bend extremely hot air.Then they learn Aang's unknown brother has a grandson that has all of Aangs Avatar attributes so the gang deides to let him travel with them so he can learn all the elements like Aang.While Zuko's secret half-brother breaks Ozai to restore is former glory and powers by destroying the avatars

I think you should write a story about it, and put it up on fanfiction.net or in your blog, as those are the placse for your stories and not here (as stated in the rules)

But, welcome to the Avatar Forums!

Welcome!

And, that's never gonna be a good case for Mike and Bryon, seeming the series already ended.

Hey, welcome to the forums. It's always good to have some new members here.

Just to let you know: There is NO book four. It's been confirmed that Aang and Zuko's stories are over. And Jet's dead. Mako's dead, and we're all sorry Avatar's over.

Try lurking- it's really helpful.