A Brief History of the Multiverse

It is well known that there are barriers between worlds. Once upon a time, these barriers were presumed to have fallen after Ansem, Seeker of Darkness, attempted to plunge all of the worlds into darkness. However, he was defeated by the Keyblade wielder Sora, whose restoration of the worlds that were taken by the Heartless restored these barriers. But, unbeknownst to most, not all of the barriers fell. It is said that all of the stars in the sky are worlds, so why is it that Sora only ever visits a fraction of them in his adventures?

It is because only a small portion of the barriers fell at a time.

However, since the return of Xehanort and the awakening of the Sleeping Worlds, more worlds than ever are visible on the horizon. Xehanort and his twelve disciples' search for the hearts required to fulfill their plans has caused them to meddle with the natural order, breaking down all of the barriers at once. Thousands of worlds have been revealed, many unaware of the existence of other worlds or the danger that they were in, only that strange, malleable blocks have been raining from the sky like a meteor shower.

But this smashing of the barriers had an effect that even Xehanort could not have foreseen.

Think of the Realms as rings. The innermost ring is the Realm of Sleep, containing the dreams of worlds themselves. Inside of this ring are yet smaller rings, of dreams within dreams. Thus, the ring surrounding the Realm of Sleep is the Realm of Waking, which itself is split into the Realms of Light, Darkness, and Between. This is the realm of the physical.

But what if the Realm of Waking itself is a dream?

The Realm of Reality is the outermost ring. Here, events within the Realms of Waking and Sleep are dreams that everyday people have, or day dreams or just ideas. These dreams are translated into entertainment, seen as fiction, made into video games. This is our 'real world'.

The destruction of all of the barriers between worlds have created echoes felt in all three realms. All worlds in the Realm of Sleep have awakened, creating even more worlds that were potential targets for Xehanort. Strange rips in space and time appeared in the Realm of Waking, displacing people from one world to another; this was after sightings of strange hooded figures watching from afar.

But in the Realm of Reality, there were even stranger reactions. Normal people, though often young due to having a larger capacity for dreams, simply disappeared. All memory of them was erased, like they never were. And they awoke in the Realm of Waking, sometimes with strange new powers.

This event would come to be known as The Great Convergence.