The Dragon Riders and The Avatar

It's been over 400 years since Avatar Korra and four Avatar's have came after her but alas they have left nothing for the new avatar; Avatar Liang. The era of true peace has been brought in by The pillar of six Avatars of Harmony. The new avatar has been made into a figurehead, a mockery of his previous incarnates; He decides to leave the world that no longer needs him. He lives in the Spirit world for a year when a mysterious portal opens and leads to a strange world.

The Dragon Riders see a mysterious portal open up on the other side of Dragon Edge, they find a strange boy who has control over the four elements water, earth, fire, and air with there sub elements. Could this boy who claims to be someone called the "Avatar" help them with the Dragon hunters?

I do not own Avatar the last airbender or How to train your dragon only the character I made up is my own and possibly a few other things in the future.