Discord: Your world is special. We call it the Borderworld, because for whatever reason, it's chock full of portals and gateways to other universes, such as the one your mirror relies on, and it has a habit of growing pocket universes around itself. There are eight such pocket universes now, each one about the size of your entire solar system, and each one containing a parallel version of it in its entirety, including Earth. Collectively, Earth and its eight parallel versions are the Nine Realms, connected to each other by magic as ancient as the worlds themselves. You ponies are familiar with a few, even if you don't know it. The breezie homelands, the Dreamscape, and even Tartarus itself are all located elsewhere in the Nine Realms from Equestria. Somehow you ended up in the Great Abyss, one of the Realms of Order, and now I've taken us away to a different realm, but for whatever reason, I can't take us straight back to the Borderworld. I don't know why, but I can only assume that something is reinforcing the dimensional walls around us. Maybe it's natural, or maybe something wants to make sure our coming here is a one-way trip. I may be able to get us back home, but it could take a while.
–Something Cosmic
, Chapter 1.
, Chapter 1.Twilight: You're really going to do this? You really have to embarrass me in front this world's nobility?
Discord: Always, Twilight. Always.
–Something Cosmic, Chapter 2.
