This is officially a Dishonored/My Little Pony crossover.

Princess Celestia, Luna, Cadance, and Twilight Sparkle are all rulers of Equestria. Rulers of a country that is often considered the most luxurious of the bunch. Before the plague, it was a thriving nation bent on creating, perfecting, and enduring the meaning of harmony. And attaining the mantle as the wealthiest nation in the world.

Yes, Equestria was something that even made many other wealthy countries cringe. That was all before the advancement of the plague from a not so great Continent; Europoniea. From there, that was the real end of the golden era for Equestria.

Suddenly you were filled with endless cries of agony, riots in Manehatten, lawless cities like Seaddle, and once rich towns like Dodge Junction. Bodies of ponies started to mount up, and ponies from all over started to shun the princesses.

Like as Celestia says, later becoming famous for quoting publicly; "Blame the rats, blame those putrid rats."

Authors note: I have officially written a crossover, don't be mad that this is based off a really successful game with a brilliant story.