Nicely done! This story has all the foundational elements needed for becoming an epic. You have suspense, mystery, and perhaps most importantly, impeccable grammar and spelling. Your characters are all written true to canon, including but not limited to the dorky humor of Sokka, which many writers fail to capture. All this said, it's time for a bit of constructive criticism.

(I should mention, first, that I don't often write constructive reviews unless I truly believe a fanfic has real potential, so please don't think of this as a flame. On the contrary, I really hope you take the advice you find pertinent to heart so that us humble readers can look forward to reading more of your work in the future, and perhaps one day on bookshelves across the globe.)

I feel as though this fanfic could be greatly improved simply by going into more setting detail. I gather from keywords that your various cities at the compass points, and Laput in particular, are supposed to be glorious, awesome settings, but as a reader I feel a bit cheated that the characters in the novel get to see these wonderful places yet I cannot due to lack of description. This would be excellent if the work was a script for a play (and designed to be enjoyed through performance and not scriptual study), but alas it is a story, a novella - a fanfiction.

Likewise, some more description with the characters and their actions would be well-recieved. For example, you use 'said' often as a speaker tag, or sometimes 'asked.' Sometimes alternate speaker tags can relate more exciting or engaging images to the reader: 'shouted' or 'growled.' Your dialogue, as I hope I expressed earlier, was impeccable for giving shape to your characters; simply expanding upon the characterizations evident in the dialogue in minute actions or appearances will do your writing a world of good.

This is especially important with OC's, or invented characters not present in canon. We should have a hint of Aura's duplicity, for example, in one tiny mannerism or action (such as a turn of the mouth, or tightness of the eyes when speaking about a controversial topic) which would be obvious in retrospect but at the time raised but the smallest of red flags in the reader. Such a hint is only possible through your descriptions of her actions, tiny minute details that can be interpreted in many ways.

Though I desired some more detail in much of your writing, your story is sound and dialogue refreshingly in character. Also, I am in love with the simplicity of your sentence structure. The story unfolds in a way that forces the reader to keep reading, to find out what happens next. It is an excellent method to keep your audience interested in those often dry lead-ups to the major plot points of the story, but unfortunately that same brevity leaves something to be desired during those aforementioned important plot-points, such as the final confrontation. At worst, the brevity results in a foggy explanation of events; I did not, in actuality, have any idea what was happening after Zuko took out the Air warriors in the tunnel because events progressed too quickly afterwards.

Nonetheless, your writing is very entertaining, your style quick and characterizations sound. I would very much like to see and read an expanded version of this fanfic, because as I said at the beginning, it has all the makings of a much-loved (and much-reviewed!) epic.

Please, never stop writing. One day your words will have the power to change lives and captivate the world.

nice, i've readed all the chapters and I'm impressed, great job!