A/N

Probably self apparent, but I'll specify that this is based on the context of the episode Dragon Quest. I will admit that the character choices are a bit of a stretch, considering the lack of interaction in the series so far, but I prefer to use canon characters rather than OCs when possible.

The Butterfly Effect

"Hmm…according to my calculations…"

"You know doc, you could just get a regular clock instead of having to rely on an hourglass."

"True…I could. But hourglasses are cool. Like bowties. And certain stage projections that seem to encapsulate every sub-genre of speculative fiction."

Doctor Whooves expected the pegasus to roll her eyes at that, or make some other physical display of her contempt for the realm of fiction. But still, if his studies of time had taught him one thing, it was that while having expectations wasn't bad, you had to accept that they could be trounced in an instant. That he was still talking to Rainbow Dash of all people further backed this up.

"But anyway, I'd be glad to join you on your little…um…"

"Nature watch."

"Uh-uh. Of course."

Whooves (or "the Doctor" as he liked to be called-his surname had been the butt of too many pun-based jokes in high school) turned his gaze away from the hourglass nestled on his desk. He'd given up counting how many grains of sand there were in it, but suffice to say, there were enough to mark a full day, and with enough potential volume to tell him what time it was. Rainbow Dash still stood there-glad in one sense, yet seemingly agitated in another. Maybe she needed a banana.

"So…" the Doctor began. "I…never expected you to be the outdoors type."

"Course I am," the pegasus declared. "I'm an athlete, haven't you heard? Or did I move too fast for-…"

"No, as in…willing to stand still," the Doctor interrupted. "I mean, this nature watch…usually you're whizzing above the birds and the bees, not watching them. I mean, I could understand you wanting to see the Great Dragon Migration next week, but-…"

"Sometimes…you need to give the mouse a ball of string," Rainbow murmured, glancing outside at a white rabbit following another pegasus that the earth pony couldn't identify. "Give them some string, and they'll follow it…"

"Hmm…like string theory?"

"…sure, why not?"

The Doctor considered himself fairly well versed in the nature of the pony psyche. True, he'd given up attempts to create a positronic brain years ago (or any brain for that matter), but he was willing to make a few inferences-that Rainbow Dash didn't want to go to this nature watch, and that the only reason she was willing to was that it would have some kind of payoff in the future. Yet in the midst of that, she was apparently willing to single out the first person at her convenience to share this trip with. Why not one of her usual cliché, the Doctor didn't know, but…well, that was pegasi for you. Light on bones, and apparently light in a certain muscle protected by the skull.

"Anyway, I best be off," Rainbow said, glancing out the window and, as far as the Doctor could tell, seeing a white rabbit looking back. "See you at the butterfly watch doc."

The Doctor froze. Grains of sand dropped. Dropped as quickly as his temperature.

"B…butterflies…" the earth pony stammered. "Did…did you say…butterflies?"

"Um…yeah?" the pegasus asked quizzically, turning away from the white rabbit and whatever potential important date she was potentially late for. "The Great Butterfly Migration. Didn't I mention that?"

"No!" the Doctor exclaimed, feeling as if he'd just swallowed a pear. "You didn't say anything about butterflies! I…I…sorry, I can't come…"

"But…but you said…"

"Yes, I said I could come earlier," the Doctor admitted, turning back to his desk and looking for a screwdriver because…he needed to do something to take his mind off butterflies. "But that was before I knew you wanted to take me to see…those…things…"

Finding a screwdriver, the Doctor began searching for the piece of parchment he kept to record his ongoing experiment to make it sonic-something that a unicorn might be able to do, but he was a scientist dammit, not some horned git who thought they were better than everyone else who could use magic. But if unicorns were the most arrogant pony sub-species, than pegasi were the most stubborn. And flying over his shoulder, Rainbow Dash was proving to be no exception.

"Doc…they're butterflies…" the pony said, her tone hovering between condescending and puzzlement. "Why in the name of Celestia would you be afraid of a butterfly? I mean, dragons I could understand, but…"

The Doctor sighed. "Rainbow, have you ever heard of the Butterfly Effect?"

"What, the book Twilight leant me? I'm still on Daring Doo, but-…"

"No, I mean, the scientific principle," the Doctor said, turning to face the pegasus. "The sensitive dependence on initial conditions, where a small change at one place in a nonlinear system can result in large differences to a later state. Part of chaos theory, where…look, I study time, Rainbow. I know how sensitive time can be. Even a butterfly flapping its wings one more time than usual could result in a cyclone on the other side of the world. I…I just can't stand them…"

"…you lost me at sensitive dependence."

"Well that's your problem."

With that, the Doctor turned back to his work. He didn't glance back at Rainbow Dash. Not as she flew away, not as the door opened and closed, not even the exclamations of "Rainbow where have you been?" from a voice that sounded like another pegasus, but outside his own group of friends. He didn't want to look at anyone who might want to associate themselves with butterflies. Polluters of time, and worse…

Worse, because he knew what they could do. From his personal experience…yet no-one ever believed him…

Because no-one ever suspected the butterfly…