Ok, so I watched the Avatar origin episodes...
Click here to see the hidden message (It might contain spoilers)
I thought it was going to be a letdown, but it was alright. Not great, but I mostly liked everything about it. Except for the dark spirit part. It reminded me of Samurai Jack.
Long ago in a distant land, I, Vaatu, the shape-shifting Master of Darkness, unleashed an unspeakable evil! But a foolish human warrior who mastered the four elements stepped forth to oppose me. Before the final blow was struck, I tore open a portal in time and flung him into the future, where my evil is law! Now the fool seeks to return to the past, and undo the future that is Avatar: The Legend Of Korra!
They have taken the hearts and minds of our leaders. They have recruited the rich and the powerful, and they have blinded us to the truth! Our human spirit is corrupted. Why do we worship greed? Because, outside the limit of our sight, feeding off us, perched on top of us from birth to death are OUR OWNERS. They have us! They control us! They are our masters! Wake up! They’re all about you, all around you!