Traveling between parallel universes is impossible, especially during the process of regeneration, but the Tenth Doctor doesn't have time to question the facts. He's just been thrust through a tear in the fabric of reality, gotten a new body, and landed on a planet called Equestria. Specifically, he's landed in the worst possible place in all Equestria – somewhere that's ready to unleash a “big ol' storm of chaos”.

That's just the beginning of the Doctor's strange new lease on life: there's a whole host of mysteries to explore. Who is Derpy Hooves, the gray pegasus who understands more about him than even she knows how to explain? How does Princess Celestia already know him? And what's the truth behind the Order?

Above all, the Doctor needs to discover if this new universe can heal the wounds he suffered in the last. Only one thing is certain: there's an awful lot of running left to do.

(Warning: For those of you who haven't watched up to the Doctor Who episode 'The End of Time'... spoilers. Also, this story begins between Seasons 2 and 3 of FiM, and things start to... diverge from there.)

Side stories can be found at The Merely Mundane Tales (of a Mad-Pony in a Box).

'John Smith' has settled in Ponyville with his wife and two daughters for many peaceful years. When the TARDIS gets a temporal distress call, Doctor Whooves and his family find themselves lost in time. Now Derpy must contend with not only monsters and maniacs, but the future and past versions of her husband!

The Doctor has lived a long life, and he's seen a few things.
He walked away from the Last Great Time War. He marked the passing of the timelords. He saw the birth of the universe, and he watched as time ran out, moment by moment, until nothing remained. No time, no space, just him. He has watched universes freeze and creations burn, he has seen things you wouldn't believe; he has lost things you will never understand. And he knows things: secrets that must never be told, knowledge that must never be spoken, knowledge that would make parasite gods blaze.
But in 909 years of time and space, he has NEVER seen ANYTHING quite like where he just found himself.

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Featured on: 7-12-14, 8-22-14, 9-8-14, 9-20-14

The Doctor is fascinated by this strange new species of ponies in this strange new world of Equestria. He wants to learn everything he can about them. You can't blame him for wanting to know how pegasus wings work, but you'd think someone his age would understand personal space.
Fortunately for him, Ditzy is very patient and understanding of his antics. Any other pegasus probably would have bucked him in the face for touching their wings without asking.

T for some suggestive humor. First-person, Ditzy's POV. Cover art is mine.
Not romance-heavy, but there's probably just enough to warrant the tag.

Ditzy awakes after an evening out at one of Pinkie's parties. Her vague memories of the previous night were brushed to the back of her mind, but just as she was about to start getting ready for her day, a surprising arrival causes her day to take a turn for the unexpected.

This is my first published fanfic, so if anyone has any helpful criticism then feel free to send a message my way on how I can improve things!

Princess Twilight Sparkle and her friends have faced endless troubles while ruling Equestria. There's never been a challenge they could not conquer.

But the end of the world has come, and nopony can stop it.

Contains narrative that jumps ahead into the future, several original characters, a despondent princess, probably some crying, and the magic of friendship.

A huge thank you goes out to Semillon, who beta read this story and provided some invaluable critiques.

This story is a sequel to Old Habits

It's Steel Song's day off, and he's got plans. Plans of the relaxed sort. He's going to eat out somewhere besides the Guard cafeteria. Enjoy Canterlot's parks. Visit his family. And then, spend the evening with the most amazing mare he's ever known.

Of course, when he bumps into a strange brown stallion in a Canterlot square, it's hard to not be a little suspicious. Especially when said stallion talks as if he's known Steel for years, and they've never met before. Surely it can't hurt to follow the stallion and make sure nothing's wrong, right? Of course not. After all, it's a day off.

Fourth of the Side Stories to The Dusk Guard: Rise. Familiarity with Rise is not required per se, but recommended.
Side Stories so far:
Carry On
The Definition of Strength
Old Habits
Emoticon
Remembrance
Trust

The Saga has a TV Tropes page! Please help keep it up to date!
Special Thanks to Jorlem and Sinister Voice for their help pre-reading, editing and getting a summary together.
Art by FaisLittleWhiteRaven

Females in the Equestria Girls universe have proportionally excessively long legs. For Principal Celestia this has become a matter of some concern. Perhaps a doctor's visit can help her find a solution.

Time Turner struggles with fundings for his new inventions, as there is no need for non-magical machines anymore. Derpy has build something to help him out, but he is shocked by what it does.

This story was written for Bean's Writing Group prompt "Legal Problems" with the bonus "Existential Crisis".

Whenever Time Turner touches a pony, he knows how and when they are going to die.

This makes living a regular life rather difficult.