Applejack sat on her haunches, eyes wide and hat in hoof, staring at the scene unfolding in front of Ponyville’s Golden Oak Library. Leaning slightly to the side but unable to tear her gaze away from the impending carnage, she muttered, “Them two been together, what, a year now?”

Cowering behind her quivering pink mane, Fluttershy nodded. “Oh, I think so. Should we, um, intervene?”

“And do what, Sugar?” Donning her hat again and pulling it low, she shook her head. “Rainbow Dash could Sonic Rainboom half o’ Ponyville into a crater. Y’all saw how she helped demolish Barn Four? An’ Twilight could turn everypony in the whole durn town into salamanders or newts or some such without even breakin’ a sweat.” Turning down the lane to give the Library a wide berth, she added, “Nope, I ain’t gettin’ ‘tween them two.”

“Salamanders would be okay. They’re very nice.” Fluttershy ruffled her feathers and followed the farmer, still shaking with every step. “You’re right, but I still don’t want to see our friends in an argument.”

“It’s not an argument!” screamed the purple and blue ponies.

Muzzle to muzzle with the Ponyville Regional Weather Director, Twilight’s lip curled as she snarled, “You’re joking, right? I was born for this! This is what I trained for! It’s in my blood, Featherbrain, and if you know what’s good for you you’ll call this off before somepony gets hurt.”

Dash flared her wings and dropped her forequarters. Her magenta eyes narrowed as she growled, “Oh, no, Egghead. You brought this on yourself. Rainbow Stupendous Dash does not back down from a challenge, especially one she’s got locked up! Back off, Twi - this one’s in the bag and it’s all me.”

“No way, no day!” sneered the librarian, her horn crackling with bolts of lavender lightning. “You’ve been getting by on reputation and history. What have you done lately to back it up? Nothing! I didn’t spend my life learning from Princess Celestia herself just to let some overgrown bluejay insult me and everything I do!”

“Oh, so little Miss Purple Pointy Pony thinks she can do better? If that’s the way you wanna play, filly, then you’re on!” Lifting an azure hoof, she spat on it and offered it to her challenger. “Shake on it, Sparkle! You know the terms, right?”

Twilight grinned and returned the gesture with a slickly spitty hoof. “You’re on. And I know you remember what’s going to happen when I win.”

“I know what you wish would happen,” leered Rainbow, “but you can forget it. This one’s a slam dunk for yours truly! Two weeks, Egghead. Go!” The librarian vanished in a popping flash of purple sparks as the pegasus rocketed into the sky, trailing rainbows as she shot toward a floating cloud-house.

Some days later Applejack was closing her apple-stall for the day when she spotted a diminutive purple dragon trudging through the market district, an overloaded red wagon slowing his every step. “Spike,” she called, “need a hoof there? Sweet leapin’ Luna, think y’all got enough quills an’ ink? Looks like y’all musta’ cleaned out the scroll store, too!”

Spike paused, panting, and shook his head. “Nope, I’m okay. Gotta get this stuff back to Twilight. I haven’t seen this little of her since her final exams in Magic class!” Picking up the wagon handle, he continued as he walked away, “Funny thing, though. Half this stuff she uses and the other half she leaves out on the balcony every night. Gone every morning, too. That mare just gets weirder and weirder.”

Two weeks after the confrontation, Twilight and Dash smiled and waved cheerfully as the mailmare deposited two large packets in the library’s mailbox and wobbled off on her route. Twilight offered a sealed envelope to Rainbow as she grinned. “You first, Dash!”

Dash stopped whistling and flexing her wings long enough to take the letter in hoof. “Good news before bad, huh, babe? Okay, here we go! ‘Dear Prismatic Charge, Cloudsdale Aeronautics Quarterly is happy to announce that your article Techniques for Control and Dissipation of F4+ Tornadoes has been accepted for publication. It will appear in the Autumn 1007 AE (7 ALR) issue. Included here please find an offprint for review and final corrections. Sincerely, C.A.Q. Editorial Board’.” Pumping her hoof in the air, she leapt to treetop height and shouted, “Yes! Who’s the mare? I’m the mare!”

Twilight waved a hoof nonchalantly and smirked as she said, “Hold your horses, Rainbow, the best is yet to come! And here for the victory, I present… ” Opening her envelope, she bowed and read, “ ‘Dear Ms. Sparkle, We thank you for your submission entitled Use and Abuse of the 53rd Sub-Magical Element in Cross-Polyvectoral Transformation. We found it exceedingly well-written and researched. However, though ours is a well-read and technically savvy readership, we found the article perhaps too technical and erudite for even our most magically advanced unicorns to comprehend. We must therefore decline your submission at this time, and we hope you will consider re-submitting a less-advanced piece in the future. Yours, Editorial Staff / Canterlot Journal of Advanced Magical Theory'.”

Eyes wide and watering, jaw hanging open and ears drooping, she dropped the letter to the dust. Moments later she felt hot breath in her ear as Dash whispered, “So. Totally. Awesome! You knew the bet, and it's time to pay up. Here, Twi, I took the liberty of writing the letter for you. Just have Spike send it, and we’re even.”

Dear Princess Celestia,

Rainbow Dash is the sexiest mare in the air. She makes my heart quake and my booty shake.

Sincerely,

Dashie’s new pet,

Sparky T

Author's Notes:

TMP Prompt # 246.

53rd Sub-Magical Element = Trollestia reference.

No way, no day = from the movie Heathers.

If Twilight had won the bet, this would have happened. Silvernis, I am soooo jealous I didn't write that piece!