UnDisclaimer: Yes, I created this character, and No, He's not what you think he might be. No questions please.
A child was born into a very powerful clan where each person of the clan could control an element of their own. This child happened to control an element that is only meant for the best of the clan. His great grandfather controlled the fire element, which only in rare births, is accompanied by a powerful dragon spirit. When his great grandfather died, the spirit went down the family tree searching for a person strong enough to contain its power.
Many years later, the spirit had found Arashi, a young baby boy. It was almost as if it was his destiny as he was born on November 5th, the day of the dragon. Throughout his life, Arashi spent most of his time either training or alone. As he grew, so did his power, as did the dragon.
One day when he was training alone, he noticed something out of the corner of his eye. When he turned, he barely escaped a kunai going straight for his head. Before he was able to completely turn around, he was attacked by a ninja, but he could not recognize the sign of the village he was from.
The ninja had scarred Arashi from his left eye down along his chest. Arashi grew very angry and retaliated against the ninja. The fight only lasted about 30 seconds until Arashi dealt a fatal blow with his enflamed fist. Fearing that there may be more ninja and for his sickly mother's health and life, he ran home very quickly. Meanwhile at his house, his mother was in fact being attacked. When he arrived, he found his mother dead, lying on the floor. He noticed his brother running out of the back door. He immediately thought his brother had killed his mother.
He battled in his mind between the choices of going after his brother or tending to his mother. He didn't spend too much time thinking as he rushed to his mother. He checked for a heartbeat, but to no avail. The anger had built up inside of him to a point where he couldn't contain it. But the sorrow was also overwhelming. He felt like killing someone and busting out in tears at the same time. He couldn't bare it anymore. Arashi let his feeling take over and let out a roaring scream. An immense wave of chakra burst from him and the dragon spirit emerged, engulfing him in flames that did not burn him or his mother.
He started to have flashbacks of his mother, brother, and he. He thought of all the times they had together. It was then that he vowed to kill his brother. The next day, after he had settled down and buried his mother, he noticed that the dragon spirit had left a mark on his right arm, almost as if the dragon had sealed itself inside of him. It bothered him that a spirit that powerful could be resting inside him, so he wrapped his arm up so no one else could see.
He felt he had to find direction in his life so he went on a quest to find the Village Hidden in Leaves(Konohakagare). After Arashi had been traveling for a while, he didn't recognize where he was so he figured he was lost. After a while, Arashi met Kakashi Hatake and Alieu Uchiha(she'll be a close friend later on).
Immediately Kakashi notices a mind blowing amount of chakra in Arashi. They talk, eat, and joke just to pass the time. The next day arrives and they prepare to depart. Before leaving, Arashi asks Alieu for directions and she tells him about five different ways to go just to mess with him. She never really tells him the actual way and leaves with Kakashi. So Arashi continues his quest, completely confused by Alieu's antics.
Weeks later, later Arashi arrives at a crossroads. He takes a road and happens upon a bridge. Suddenly, the air gets increasingly thick with mist. A voice speaks, No one is allowed to cross this bridge. Arashi replies, Says who. The Demon of the Mist.