The entire course of history can be changed by a single butterfly flapping its wings. So what if an entire war was won instead of lost? What if a King never existed?
Nightmare Moon received an odd omen from the one who destroyed Equestria's past and now must contend with the possibility of her sister's anger coalescing into a true being while Nightmare Moon tries to retake Equestria from the King and Queen.
If Ponyville's new repair-pony gets his way, the Mane Six won't even know he exists - and nopony in Ponyville will miss him for long once he's returned to Earth.
Taking care of a whole kingdom can be hard, teaching/learning how to act in the modern times is harder. Keeping up with Twilight is tiring, dealing with their nephew is worse. Thank Faust for their new butler.
Pharynx won't ever accept these new Changeling customs. He won't ever accept the lovey-dovey ways of his peoples. Even on his death bed he won't ever sympathize for the Ponies like his people do. Maybe he'll tolerate, for the sake of Her.
The Castle of the Two Sisters has a long history, dating back to Equestria's early beginnings. As such, many artifacts still rest in its many hallways. Relics, ancient books... and old experiments.
Magic is a strange thing, and Equus is darker than most realize, but when a piece of the grimdark future is dragged through, a cop and her human friend become awash in bodies and a hate mandated from the divine.
Legends speak of a being beyond the strength any mortal can possess, the one who created the cosmos itself. These tales are no mere legend though, the creator now walking amongst them...but not how many of them would have thought he would.