Celestia is in love with Twilight. And has been for a long time. Yet she doesn't tell Twilight. Why? Because she's waiting for the perfect moment. She's got time after all.
After the changeling invasion, Applejack hears from Princess Luna the history before Equestria, before the three Tribes, even before the Age of Myths. The origins of Tirek, and his relationship with his brother Scorpan are revealed.