I'd recommend 'Avatar: The Next Generation'. It takes place a few decades after the end of the original series. It follows the new Avatar, who is a waterbender this time, and his adventures. The fanfiction is full of action - packed battles and also delves deep into the new political situations in the four nations.
Avatar: The Last Airbender is indeed an original story. It has its own distinct style and narrative that sets it apart. The combination of elements like bending powers, diverse characters, and complex story arcs make it a one-of-a-kind creation.
Definitely not real. It's a fantasy world crafted with unique characters and magical elements that exist only in the realm of imagination and storytelling.