Young Princess Cadance has gained the ability to see ponies' emotions, but sometimes what she sees puzzles and confuses her. Surely Princess Celestia can't actually be depressed?
700 years have passed since the night Nightmare Moon defeated her sister Celestia and cast her to far off lands, stripping her of power. Now, the hate in the younger sister's heart has faded, and she has brought Celestia back to Equestria.
Twilight was surprised when a straight-maned Pinkie Pie showed up at her door on a cold, winter night. The pink earth pony had brought her a gift, but the meaning behind it went much further than a simple present.
Tony Stark considers himself a fairly open-minded guy, given the whole Iron Man thing and all. There's nothing that can't be explained away by science. ...Even a very tiny lavender unicorn who ended up in his lab. Maybe. Pre-Avengers
Rainbow stumbling across Pinkie drinking went a lot better than Pinkie could have hoped, what she didn't know is what would come from it. She thought she was the only one of her friends that was miserable and wearing a mask, she was wrong.
Mister Lonely Heart is a self-styled "Grievance Counselor", a changeling who mimics ponies that his clients have issues with. When Twilight Sparkle pays him a visit, he finds out how painfully neurotic the Princess of Friendship really is.