Princesses Twilight and Celestia were dating when Tempest arrives at Ponyville to learn about friendship. When Twilight and Tempest fall in love, Princess Celestia doesn't handle it as well as she should.
When the descendants of the major villains are called to live in a better place, it is up to them to make a choice: to follow in their parents' footsteps or to choose the path of heroes.
You've found an "interesting" book recently. You don't know what it is, or why it was hidden in the back of Twilight's library, but you feel so compelled to read it. And keep reading it. And keep reading it...
In the sequel to The Lieutenant, Tempest Shadow goes back to her home town along with Twilight and Celestia. But while on their incredible journey, they come across dark forces outside of Equestria.
Tempest Shadow has an untold past that nopony really understands. One day, she tells Twilight Sparkle what actually happened on the day she lost her horn and also learns a valuable lesson; that everypony is truly wonderful in their own way...