Thread:CITRONtanker/@comment-26888167-20170706181043/@comment-26888167-20170725031116

By an interdimensional portal. I was going to write a story here about that. Basically, Bright Spark attempts to create a new machine to defeat Red Fork, one that would send him to an unknown dimension. However, things didn't go as planned, and not only Red Fork envded up entering the portal, but also Lemon Glass, Blue Ocean, Bright Spark and Twi-bot.

Other ponies join in later: Dark Shadow and Black Gem enter the portal as part of a mission they have as Crystal Empire agents. Twilight enters the portal when she discovers that's where Red Fork went. And, there it is, basically.