It has been five hundred year since the reign of the Princesses. A curse upon the land had forced there to be a King and Queen, though their foals would never become Queen or King, as they haven't since the curse. Unless...on the low chance, made more impossible by the curse, two fillies were born of two different allignments. Until then, the new King and Queen would be picked from the fillies and colts of the civilians, of which one of each gender would have the allignments necessary of the Royal Family.
Now, there had been peace among the many kingdoms of Equestria for many years, but as unease of a solid royal line and uneven power in Canterlot grew, so did the rise of revolt.
The stress of being Queen is not lost on Milky Way, daughter of a humble farmer Earth pony. She must deal with her loyal but idiotic husband, Solaris, as well as her young daughter, Princess Nebula. Not to mention rumors of revolution if the Royal line doesn't settle. She must also find the next King and Queen before they're thrown out of the picture.