Naruto/Korra crossover

Origins.

The sound got louder and louder as whatever it was approached.

Atoki squealed, and cowered in fear behind Ikki.

'Sage mode already wore off!' Naruto thought frantically, as he tried to remember how many consecutive times he had used it. '...How much can I use it? I've used it, let's see...'

But his thoughts were interrupted, when the thing finally got to them, and they got to see it in all its horrible glory.

It was a giant, gray creature that had mismatched, yellow-red eyes, a large, misshapen nose, and a gruesome mouth, that had different sizes of teeth protruding out of it. It had two large arms that touched the ground as he stomped to them in a sort of slouching position, and his legs were short; it was amazing that they could maintain his balance.

Basically, it was an ugly creature.

Naruto looked it over and pumped his fist. "I would guess that you're the boss?"

The thing smirked; or, it probably did. It's mouth was too crooked with too many teeth to tell. "I am." His voice was deep and growly.

Ikki pat Atoki on the head, and then glared up at the boss. "You scared him!"

The boss chuckled. "Atoki? You traitor. How dare you bring these pests here to interfere with my plan? You shall be punished severely."

It spoke with verbal conciseness, which didn't match its face at all.

Naruto made a fist and pumped the arm with that fist. "You won't be punishing anyone! You'll be the one who gets a beat-down!"

The thing laughed; a truly terrible, and frightening sound. "Really? You mere humans think you can beat me? I am not one to be trifled with. You all may have taken down various powerful beings, but I am different. I have studies all of your respective abilities. I am the one of the shadows of the depth. I can predict your fighting styles and movements."

He then pointed at Naruto. "Except you. You are a mystery to me."

Tenzin was what seemed like almost in awe of this creature. "How can you possibly know so much?"

It turned to Tenzin. "I am a gulfskin. The greatest of my kind. A spirit that dwells within the waters. I gained power beyond other spirits; enough to temporarily escape the spirit world in a weakened state. Before you took down Vaatu, and opened the spirit realm for all to roam the worlds. But, in that time, I chose to inconspicuously track the avatar of the present time. She... disappointed my expectations. The last avatar I had met before you, was Kyoshi. Now that was an avatar."

Jinora spoke up this time, "But why did you study us? What do you get from it?"

The gulfskin thought about how to answer in a short way. "...I suppose... the destruction of human kind."

This comment made everyone go silent.

The gulfskin put a large hand on his chest. "I am a humble spirit; not asking for much, and not expecting much in return for my deeds. But humans... humans are a despicable race. How can you war so much, and do that kind of damage in so little time as a hundred years? Or how dare you shut out the spirit race, and forbid any spirits from entering the shared world? You are the villains in this story. You humans disgust me."

Naruto got a little tidbit of information from the gulfskin about this world. "Ok, but what does that have to do with you personally?"

The gulfskin shook his head. "Nothing at all. I am simply the avenger for all spirits now. We will take back what belongs to us. It's just a pity that you destroyed my device to aid me in my mission. Oh well. I'll make do with what little I have."

Atoki's eyes went wide. "RUN!"

The boss roared, and charged at them.