As Twilight Sparkle was strolling around Ponyville during a visit to Applejack, she found a new type of gem that looked a lot like a Ruby but that was more maleable and contained a new type of magic she has never seen before, so she decided to bring it to her library to study it and see what it could bring to her and Equestria for prosperity.

As Twilight was studying the rock, Spike started to notice the gem to have a very nice shape and that it looked very enticing. As Spike got closer to the gem, he felt how it was calling him, ready to bring him something that he has never tasted before.

As he ate the gem, Spike very soon realized that it even wasn't an actual gem, but something far more insidious.

Crossover with the anime Full Metal Alchemist Brotherhood, an idea that's been going around my head for the last few months, I hope you like them.