The Immortal, what is it. If you define Immortal it is a being who can never die or decay, and you won't be wrong. However for us we have THE Immortal. We don't know much about this being, but what we do know makes him someone of great importance.
Can you imagine a human incapable of death, processes complete authority over all ten elements of nature, and an unlimited supply of magic. That would basically describe a god, and you would be right. If it wasn't for the fact that the immortal is limited by how strong or fit its body is we can breath a sign of relief that it won't be shaping reality or blowing up planets.
After all there are plenty of creatures especially dragons who can destroy planets on their own. Even still someone who is given that much power to fight against foes who seek to do wrong is someone we need on our side, for the Immortal has been know to grant prosperity to those it deems to be its allies and misfortune to those it deems to be its enemies.
Then let us make sure that if what the chronicler says is true. Then upon this humans death he will be the Immortal and we must ensure the Immortal is on our side.