Derpy came to return the jar for the fireworks to Doctor Hooves. Unfortunately her clock caught on to Doc's secret breakthrough and travels to the past.
Derpy is feeling horrible ever since her husband, Doctor Whooves, and Roseluck started going on missions together. To get herself friends, Derpy goes to the Mirror Pond. You can guess what happens next.
Derpy and the Doctor. They were once so much, but now Derpy is old and dying. And she wants to go on one last adventure before she has to go. Even if she doesn't want to go.
Derpy is asked to house-sit for the Doctor. She's eager to help out her favorite stallion... until she has one of her mishaps and smashes one of his watches. How expensive can a "Ponex" watch be, anyway?
When a blue box containing a mysterious pony lands in Ditzy's yard, she calls for the Elements. But the more she speaks with this "Doctor," the more convinced she is that they've met already.
Dinky is different. So is Sparkler. They both have two hearts, Dinky has crazy weird skills, and both are unicorns, when both parents have no realation to that. Derpy won't tell them anything about there time lord father, but things start getting bad
After fives years abroad, Princess Cadance returns to Equestria where she is immediately placed under the protection of prodigy Battle Mage, Twilight Sparkle.