Continuing the expanded empire theory... somepony with a lot of knowledge of the elements of harmony has been interfering in the human world. Could celestia have sent her faithful student sunset shimmer as a spy into the human world. Only sunset having a thirst for power attempted a coop with humans to overthrow celestial. Foiled by princess twilight, sunset remains adverse to celestias rule and each time celestia sends equestrian magic to the human world sunset shimmer defeats it. (The dazzlings, midnight sparkle, gloriosa, the mirror, the phone) all celestial pawns in her plot to conquer the human world. Sunset (the defender of earth) is laying low playing princess twilights friend game and acting like she's on celestias side while derailing each of celestias attacks. All waiting for the opportunity to once again take the thrown of equestria and the human world. ALL HAIL QUEEN SUNSET SHIMMER!!!
(After all it is her name, sunset, as in the setting of celestia.)