In the beginning there was Nothing. Then Nothing was divided, and the two Multiverses came into existence in an explosion and implosion of raw primal energy. Each Multiverse was a mirror of the other, one formed from positive primal energy, the other from negative.
The two Multiverses spawned Universes, which spawned galaxies and solar systems. Planets were formed, and life crawled from the primordial ooze to begin the long journey of evolution.
Scattered throughout the Universes were fragments of primal energy, and sometimes a tiny fragment would strike a world. Reality became distorted around things touched by this energy, and rare individuals calling themselves "wizards" developed the skills to control and manipulate this power, which they called "magic". Sometimes the energy encountered a free-floating sentient soul, and instead of merely touching it, it merged with it. And so the Supernaturalis were born. These beings didn't simply manipulate the magic, like the puny mortal wizards; they were one with it. A Supernaturalis wields magic with the same natural ease as a mortal breathes air.
When a mortal dies, they are later reincarnated by the Multiverse in the eternal cycle of life and death. This transition is very stressful however, and it is very rare for a mortal soul to remember any of its past lives. When a Supernaturalis soul is born, all previous memories are destroyed as the old soul is consumed and reforged. The new Supernaturalis soul forgets nothing learned from that point on, however; after their rebirth, they become truly immortal.