Bending AU

Bending AU is a popular AU (Alternate Universe) within the Rise of the Brave Tangled Dragons fandom. In the AU, Rapunzel, Merida, Hiccup and Jack Frost are all part of the Avatar: The Last Airbender world, and often are elemental benders. Because it is not canon, ideas for this AU are shown through fanfiction, fanart, and other fan-made works.

About the AU
The world of Avatar: The Last Airbender is a popular universe for fans to use for crossovers, and this is especially the case in the RotBTD fandom. The world of Avatar is the perfect location for the Big Four to interact because of a number of reasons: it allows for the use of magic and the idea of dragons, it provides for an excuse for the Big Four to have unique traits that distinguish them, it allow for the homelands of the big four to be located in the world of Avatar, and it adds elements of competition and rivalry between the Big Four and their friendship.

In most cases, the Big Four all are from different nations, and often are known as 'benders' or individuals who are able to use the elemnts of earth, water, air, and fire. Since this AU is still very young, there is still many debates on exactly what nation each member belongs to. The world of Avatar also features one individual who is born with the power of all four elements, and these stories often focus on one member of the Big Four being the avatar, and the other three being bender masters that the avatar learns from. Additionally, the character's pets are often portrayed as their guides and companions, although not always as their true form as most creatures in the world of Avatar are hybrids.

Hiccup Horrendous Haddock III
Hiccup is an air bender. He soars through the air with Toothless for a reason.

Jack Frost
Jack has been chosen to be water because snow and frost melt and become water. Jack has been linked to air, he works and travels with it with ease.

Merida DunBroch
Merida represents fire. That's why "Hot Head" is her nickname. Merida represents water, it is flowing and free.

Rapunzel Corona
Rapunzel has a connection with earth. She was born because of a flower.

Fanfiction

 * Together Foreverby Little.StarBabe