Raava (Earth-3813)

"Vaatu cannot be reborn. Do not give in to ten thousand years of darkness. You are the Avatar."

- - Raava to the Sage of the Six Paths

Raava was the spirit of peace and light who became the Avatar Spirit after fusing with the Sage of the Six Paths. One of the oldest known spirits, she existed ten thousand lifetimes before the emergence of the first humans on Earth. Alongside Vaatu, her opposite and the spirit of chaos and darkness, she spent most of her life fighting him up until the Harmonic Convergence in 19,829 BG, where neither were able to vanquish the other.

Fighting Vaatu
In 19,829 BG, the entity Raava entered in a conflict against Vaatu, her light restraining him from wrecking further havok. However, with the arrival of the Wan during their battle, Vaatu manipulated the man into separating him from Raava. After he became free to roam the mortal world, Vaatu spread his chaos and grew stronger by weakening the light.

Helping the Sage
As he traveled, the creature discovered a hidden village that lied atop of a lion turtle. His corruption was so big it transformed the peaceful spirits that lived in the settlement into rageful entities. Duo to the intervention of Raava and the Sage, however, Vaatu was prevented from destroying the village, which led him to a fist of rage as he taunted Raava, who grew weaker duo to the proliferation of chaos, promising to destroy her forever in the upcoming Harmonic Convergence.

The Ten-Tails met with Raava and Wan in yet another conflict between humans and spirits, turning the anger of his minions against them and thus molding the light into darkness. With the battle over, Vaatu revealed to the Sage that the humans were slaughtered and that he should enjoy the last days before the end of the world.

The Harmonic Convergence
With the approach of the Harmonic Convergence, Vaatu used the spirit portal in the North Pole to gain access to the Spirit World, where he battled Raava for its control. However, he faced the spirit of light allied with the Sage, who challenged the Ten-Tails, only to be brushed away duo to Vaatu's arrogance and belief that a mortal could not stand against him. Seconds later, the duel between light and darkness started, where Vaatu gained the upper hand. However, when he prepared to kill the Sage, he merged with Raava. Neverthelesss, the dark spirit bested his merged enemy, pinning them to the ground next to the spirit portal in the South Pole just as the Convergence began.

Imprisionment
When he looked to the overlapping ot the northern and southern spirit portals, it took away from his focus on the Sage, who used that very moment to permanently merge with Raava by touching a portal near him, which amplified his chi and spiritual energy to levels beyond comprehension. In the ensuing battle, Vaatu was trapped in a chi sphere surrounded by the four elements of nature.

Captured in the cage, Vaatu's essence was sealed inside the hollow Tree of Time, where he remained restrained. However, even though the dark lord was restrained for the time being, the Sage of Six Paths knew he wasn't permanently defeated; to ensure the Ten-Tails' imprisonment for the rest of eternity, the Sage used his newfound merged powers to separate the chi from Vaatu's body with his unique Creation of All Things Technique, birthing the nine tailed beasts and then closing the spirit portals so that no human would be able to physically enter them, leading him to become the fabled "Sage of the Six Paths".