It's just the lack of a personality flaw. If other players don't have problems with it, then it's fine.
I should just start this thing now. Reserved.
BTW, the posts in the perspective of Annihilus will be black with white glow. Technically, everyone is allowed to narrate in the perspective of Annihilus, but I would suggest that we should avoid controlling the main antagonist as much as possible. If you really have to do something with Annihilus, discuss it with the players first to make sure they're fine with it.
Sigh... This will probably come out really cliched...
Among all worlds in existence, not many knew about the Multiverse, the world of worlds; they simply believed that their own worlds are the sole existence in the vast and boundless void. That was probably for the best. If the inhabitants of a world, corrupted by greed, learned about the existence of worlds other than their own, they would surely seek to conquer those other worlds. They would become interdimensional scavengers, traveling from world to world to pillage all the wealth, power, and resources they could find. Among those world-roaming locusts, the most terrible of them all was an entity named Annihilus, the Devourer of Worlds. This creature was so powerful, that it was said to have devoured entire worlds whole; such a monstrosity would not stop until it had consumed the entire Multiverse. But fortunately for us all, the Devourer was imprisoned, trapped in a tiny corner of the Multiverse for all eternity.
Until now.
Even the Creator Himself could not imprison the Devourer forever. Over the millennia the Devourer's prison was weakening, and now the seal had already exhausted all its power. The Devourer was ravenous after its incarceration for aeons, and it longed to satisfy its hunger. LET ME OUT! The Devourer screamed. Tentacles of black nothingness slammed against the boundary of their prison, enlarging the cracks that had already been appearing on the seal.
Under the tentacles' numerous strikes, the Devourer's seal finally relinquished. The very fabric of reality itself split apart at the seams, sending shockwaves and fractures rippling across the entire Multiverse. The fractures spread, touching many worlds, and pulling many unfortunate denizens of those worlds from their homes. The fractures coalesced on one world in particular, the world closest to the Devourer's prison. With crazed glee, the Devourer plunged its tendrils of nothingness into the world it was about to devour, tearing rifts onto the world's sky.
The world struck back in retaliation. A beam of multicolored light cut through a tentacle of nothingness, severing it from the Devourer's body. "What are you?" A humanoid being made of rainbow-hued light spoke, fear interlaced in its eerily androgynous voice. "What business do you have in Zanzarino's domain?!"
I AM ANNIHILUS, THE DEVOURER OF WORLDS, the Devourer sneered. I AM HERE TO DEVOUR YOUR PATHETIC LITTLE WORLD.
The rainbow-colored being gasped, its golden eyes widening. "I will not allow you!" The being cried. Twelve spheres of energy, each with its own distinct color, formed around the rainbow being. With a wave of its arm, the rainbow being sent the twelve orbs of elemental energy at the writhing mass of nothingness that was the Devourer.
The elemental spheres connected with the Devourer's body, to simply sink into its pools of nothingness. HMM, YOU ARE POWERFUL, the Devourer mused. PERHAPS I SHALL MAKE YOU MY MINION, TO ACT IN MY STEAD WHILE I RECOVER MY STRENGTH.
The rainbow-hued being backed away, eyes wide in horror. "No... Never!" But it was too late. One of the Devourer's tentacles lashed out and plunged itself into the rainbow creature's chest. The creature shrieked in agony, as its eyes slowly turned from golden to black.
RAINBOW... THAT IS YOUR NAME? The Devourer smiled, opening a void rift in the shape of a mouth. YOU ARE A "FALSE GOD", EH? VERY WELL THEN, I SHALL MAKE YOU GREATER THAN A TRUE GOD! NOW... GO TO THE DENIZENS OF YOUR WORLD, AND GIVE THEM MY POWER. SHOW THEM THE POWER OF VOID. GIVE THEM THIS POWER, AND THEY SHALL BECOME ONE WITH ME.