My five-year-old and I read through the three stories in My Little Pony: Friendship is Magic Vol 12. I first read Accord aloud to him, and he liked the way it ended. About when Accord was controlling the minds of almost all the ponies, he wanted me to stop reading, but he stayed to find out what would happen.
In this story, the dragon Discord changes into a super-orderly dragon who just wants to bring agreement and harmony to everything. His method for bringing such order is to control the minds of every pony that he can. Eventually, only Starlight Glimmer is outside of his control, and she must try to convince Accord to change back into Discord.
My son and daughter next flipped through the pictures of stories two and three. Both stayed glued to the computer to watch until they had finished scrolling through every page. They enjoy the vibrant colors, easy-to-understand facial expressions of the ponies, and the movement evident throughout.
Later I read the stories to my son. In For the Pony Who has Everything, Discord appears as a guest to Princess Celestia´s birthday. He observes during the party to come up with a present for her. His unconventional idea is to give her a day off. He disguises both of them, and the princess decides to spend her free day in Ponyville. Once she gets used to the idea (it didn’t take her long!), she thoroughly enjoys irresponsibility.
Finally, my son´s favorite was From the Shadows where a mysterious pony begins gathering and erasing history books and the memory of what the books contain. The pony friends gather to try to stop him, but they find him very illusive. He, Shadow Lock, also is able to call monsters from books in order to maintain the pony friends occupied while he escapes. Twilight eventually is able to talk with him, and discovers he is actually not a villain, but just a misguided pony trying to prevent a terrible evil from reemerging in Equestria. The story ends with the indication that the ponies will have to face the very evil Shadow Lock was trying to erase.