After the events of A Royal Canterlot Wedding part 1, Twilight feels horrific. Having pushed away her brother, her friends, and even Princess Celestia over her ridiculous claims that Cadence was somehow evil, Twilight, in her sadness and loneliness, thinks to throw away the most valuble of Celestia's gifts ... her life.
But, never one to pass up an opportunity for some good mayhem, Discord offers another prize instead ... to see what would happen if Twilight was never born.
(An homage to the classic "It's a Wonderful Life")