In the beginning, there was not.  Matter, light, energy did not exist—there was not even a void, for the very existence of void is defined only by the matter that does not inhabit it.  There was time, the force that drives all things, but it was impossible to measure as it flowed from nowhere to nowhere else.

Then, there was.  An entity, a mind, existing as pure thought.  It saw all that wasn’t, but it did not see itself.  It would later become known as Intraverse.  What Intraverse thought, became real.  Over untold ages, he created all that exists—universes, as innumerable as the leaves on the Tree of Life itself, each with countless galaxies, each containing fantastic numbers of stars.
Intraverse looked back upon his creation. “Who made this?” he wondered.  In all this time, he had seen every last atom of creation—but he had not seen himself.  He realized that it must all have been made by something that came before—he realized that he was that thing.  It was at that moment that he realized that he was a self.  He became shocked, fearful of his own power.
This fear took shape, unbidden by Intraverse.  This fear had strength like unto Intraverse himself, and knew only what had created it—fear, power, and the twin acts of Creation and Destruction.  These things it desired above all else.
Intraverse saw what he had made—an evil that defied any name.  In a panic, Intraverse froze the evil in time, putting it dormant in the stuff between universes.  There it lay, as countless civilizations rose and fell, and any memory of it that may have existed faded into the oblivion of the truly lost.

In one particular universe, in one particular galaxy, there arose a race of Immortals.  No, this is a double misnomer: they were not a race, for they had numerous species among them.  Nor were they immortal, though they lived very long.  These Immortals acted as protectors of their galaxy and those surrounding it.  They were immensely powerful, though only the merest shadows of Intraverse.
One day, a group of several Immortals set out to the edge of their universe.  These were no intrepid explorers by any means—the Immortals had been traveling to other universes for billions of years.  No, these were simply a group out for a day trip and a picnic in what is one of the most quiet places one can possibly find.
They left their universe, and traveled well away from it, skirting around the edges of others as they went.  They never left the area that had already been charted, but were soon in a particularly quiet area.
It was there that they found it.  Intraverse’s fear, frozen in time and forgotten for nearly as long as it had existed.  They did not know what it was.  Their curiosity got them too close.

It awoke.

The Immortals were people whose technology could destroy and re-create entire galaxies in a heartbeat.  Their most basic weapons would be the ultimate source of power for most civilizations.  Their most basic tools could build a mountain with a single thought; the physical strength of a single Immortal was enough to lift that mountain from its very roots and hurl it into space.  They could conjure matter from nothing at the speed of thought, they could bend the very forces of nature around themselves.
The Fear left them nothing but an atomized vapor before they could even think.
It did not take the Fear long to figure out which universe they had come from.  It made its way in the same way they had left, and soon found the realm of the Immortals.  The Immortals pooled all their strength, but any who tried to fight the Fear became nothing.
The leader of the Immortals beseeched Intraverse to tell him how to fight the Fear.

“The Fear…is something that has not been seen in a very long time,” Intraverse told him.  He took the form of an old man now.  “It lives only to dominate.  While it works toward this goal, nothing can stop it, not even I.  You must wait, wait until it has established a firm hold of this universe—or, regrettably, perhaps all of the universes.  Once it does this, it will become complacent.  Then, and only then, do you have a chance of killing it, via subterfuge and trickery.”
“There is no other way?” the leader asked.  “Many more will die before this happens.  And those who die may be better off than those who don’t.”  He had spent most of his life endeavoring to protect those who needed protection.  The thought of leaving them all helpless made him disgusted; the thought of leaving them all helpless while a nameless evil enslaved them made him sick.
“No.  There is no other way.  I know this thing, it is my unwilling creation.  I feared that the day would come when it awoke once more, so I searched deep inside myself for the way to overcome it.  All possible scenarios ended the same way, this way.”