At the Royal Wedding, Chrysalis and the Changelings were revealed to all of Equestria.
But another mask was torn away that day. A mask born for a thousand years. A mask created on one promise. A mask, that has become synonymous, fused, to its bearer.
A mask that when ripped off, causes Twilight, her friends and Luna to question everything they ever knew about the one pony, one very important pony.
At the Royal Wedding, the meaning of the phrase 'Princess Celestia' changes forever.