Despite not having much power in the real world, The Unborn, for attain its goal, is using Xion, influencing him through his power and promises.
In the Bloody Roar mythology, The Unborn represents all the life forms that could not evolve through the natural selection and all the future life forms who will born through the evolution but are not existing yet. The Unborn was a creation of Gaia, the only force which is able to choose which life form can exist or not.
As it was becoming a demonic entity, Gaia confined The Unborn in another dimension with the only escape, the Tabula of a Thousand Beasts, being sealed by the Sign of the Beast (X-Genome Code).
Bloody Roar 3In the events of Bloody Roar 3, The Unborn manipulates Xion to kill all the Zoanthropes bearing the Sign of the Beast promising him a new world far away from his "trivial world". Once, he will defeat them all, Xion would channel the power released by the Tabula allowing The Unborn to spread and take over the planet.
To help him, The Unborn gives to Xion, the Unborn form, a powerful and demonic Beast Form.
Despite his strength, Xion is defeated and the Tabula of a Thousand Beasts is destroyed preventing the power of the Unborn to awake.
Bloody Roar 4
During the Tabula incident, Nagi was mortally wounded while trying to stop Xion. She survived but with the cost to let the power of the Unborn impregnated her, like for Xion, and obtained the Spurious Beast Form. Until the events of Bloody Roar 4, she was still freed of the Unborn's influence but, as she meets Xion again and stabs him, The Unborn takes full control of her body.
As The Unborn's minions, Xion and Nagi were sent on a mission to weakened Gaia by destroying her most powerful weapon, Ryoho the Dragon. They are finally freed from the Unborn's influence when Mana casts a spell on them. Then, Xion and Nagi combine their power to shatters the Unborn.