Wan was a boy who was born at the Fire Lion Turtle. Once he became an adult, he took food from the Chou Brothers and gave the food to his friends, who are starving. Wan has been recruited into an army who intended to defeat the spirits with firebending. Wan took the use of fire from the Lion Turtle so he can play tricks on the Chous. For this act of treason, Wan has been exiled from his home. He came across the Spirit World where he met the Aye-Aye Spirit. The spirit deeply disliked every type of human. Wan told the spirits that he had been banished from his home. The spirits told Wan that there are other Lion Turtles. Wan showed the spirits his firebending technique. Wan traveled to a valley where two spirits: Raava and Vaatu are fighting. Wan didn't want them to fight. Raava told Wan it does not have to do with him. Vaatu tricked Wan into freeing him from Raava. After Wan released Vaatu, Raava told Wan that Raava is the spirit of peace and light while Vaatu is the spirit of darkness and chaos. Wan realized that his friends used his fire powers to kill off innocent spirits. The freedom of Vaatu made the spirits become Dark Spirits. Wan and Raava intervened these conflicts so there can be peace, love and understanding for the humans, animals and spirits. Wan realized that he and Raava alone cannot defeat Vaatu. Wan learned about airbending, waterbending and earthbending to defeat Vaatu at the Harmonic Convergence. With the fusion of Raava and Wan, the Avatar Spirit was born. Wan used all 4 elements to trap Vaatu so nobody can release him. Wan sealed the portals of the spirit and humans worlds so the freedom of Vaatu can never happen again. Wan described the Avatar as the bridge between worlds. Wan's goal in his life is spread peace and harmony. Later in life, the people used war and violence. Wan's lecture on peace did not work for the aggressive humans. After the war when Wan was an elder, Wan believed he failed his task. Raava told Wan that she will always live in his lifetimes. When Wan breathed his last breath, the Avatar spirit came to many other bodies including Aang and Korra.
Wan in his early life, is rash and likes trickery. When he realized his mistakes, he became aware and a pacifist.