Imagine a world where poverty, filth, and famine plague the day-to-day lives all but a very small minority of the population. Where mares and fillies are deemed of lesser worth in a chauvinistic society that values strength over reason. Where entire cities are ruled by gangs of organized thugs, and a democratic system exists only to serve as window-dressing for the power struggles of violent brutes.
Now, imagine a mare who is able to use her talents of manipulation and on-the-fly calculation to overcome the limits put on her by society to become one of the most powerful political figures in the land, and does so with ruthless efficiency. Such a mare exists. Checkmate Master. This is the story of how she received her cutie mark and discovered her exceptional destiny.
Note: This origin story takes place approximately twenty-five years before the time of both the show, and The Phoenix of the Wasteland, where the protagonist and her family first made their debut. It also shares the same setting as the latter, but on a much smaller scale. Therefore, it stands to reason that there is an all-OC cast. If you don't mind that, go ahead and read.