Corvo Attano + Pony

As a rat induced plague strikes Equestria, Dust Storm, once the well regarded royal protector of the princesses is falsely accused of killing Princess Cadence, the attempted murder of Celestia and the foalnapping of the newly crowned Twilight Sparkle.

In his prison, he is visited by a figure, the creature tells him of his part to play in the upcoming events. After months of imprisonment, Dust receives a letter to his cell.

They say a unicorn's magic is based around their cutie mark…

Revenge solves everything.