Once, during a brief conversation between Luna, Celestia, and Discord, the Spirit of Chaos lets slip a piece of information that neither he nor Luna could possibly know, having been imprisoned for a thousand years. Upon further interrogation, Luna confesses that neither she nor Discord were truly imprisoned for the millenium they were absent.
They resided in Tirelic, a parallel world where the night never ends, where abominations of terrible origin and conspicuous means make trade and commerce, and where everything is more than it ever could have been anywhere else. A land where beasts and ponies, gods and mortals, and everything in between made their homes, their lives, and their living in the place that should be impossible in the plane of existence that is improbable.
The world where Tirek won. The world where he still rules.
And where he's been waiting for Celestia for over a thousand years.
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An old collab with RainbowBob, including original Author's notes/commentary. We never finished it, so it's posting as complete because that's all there is! I tried finding it recently and it had disappeared everywhere! Except, of course, my cloud drive. Heehee.