Twilight's body was consumed by lust. Her body was oozing pheromones from every pore. Her marehood was rapidly becoming wet with lubrication and filling the air with her scent. She'd never done this before. Sure, she had fantasized about it, but usually with a stallion more her size. Somepony like Caramel or that earth pony with the hourglass cutie mark she could never remember the name of.

All of her thoughts and senses focused on her nethers as Mac lifted her tail with a hoof and planted his muzzle against her marehood. The hoof that lifted her tail moved across her flank and slid down her cutie mark, sending an extra tingle through her body as his tongue got its first taste of her pussy.

Mac's mind was rapidly being subsumed beneath the lust, but he remembered enough from prior experiences that Twilight tasted unique. Slightly tangy, as was expected, but sweet as well, with an almost honey texture. He moaned, a low thrum that transferred into his companion, and slid his tongue in further, slurping around the entrance to her most intimate place. He pressed his attack, flicking his broad muscle across Twilight's clit and sniffing deeply, the scent driving him mad as his cock hardened.

Both were panting heavily as Mac stood and moved over the smaller unicorn. She had enough presence of mind to use magic to guide his massive stallionhood to her entrance, where he grunted at the feel of those hot lips at the tip of his flare, "Twi... This... might be a bit big for ya..."

"I don't care, Mac... Just rut me."

He pressed himself forward, taking a half-step as he pushed inside. It was a tight fit, tighter than he'd felt before. He no longer doubted that the mare below him was a virgin as he pushed in more.

Twilight felt his cock enter her at an excruciatingly slow pace. She had never felt so full before in her life. It hit nerve clusters she didn't know ponies possessed and her eyes slowly crossed until his flare collided with her cervix. She looked back to see that he was barely halfway. His height wasn't the only thing that made him "Big" Macintosh it seemed. He repositioned while she lowered her front half to the ground to help brace the inevitable thrust. He pulled out slowly and thrust back in, bringing a grunt out of the unicorn.

Mac slowly began to increase his force and speed as Twilight's plot loosened up. He never went too hard, despite his instincts telling him. He didn't want to break her. As the pleasure slowly overwhelmed Twilight, she noticed something.

It began as a tingling in her hooves, spreading slowly up her legs. Looking down, she noticed her purple coat fading into black chitin as holes formed. Her mane flopped in front of her face, darkening slightly as holes formed in it as well. Unable to form words, even in her mind, all she could express was confusion and lust. Despite the transformation, it felt better than just sex could ever feel.

'Ah, right, I forgot to mention. Your first actual rutting completes the transformation into a queen. You've had some minor transformation before, like you showed with Rarity, but now you will have all the abilities of a full changeling. Don't worry, you can just disguise yourself again when you're done.'

Twilight didn't care, she just fluttered her new wings happily, humming them against the sides of Macintosh's barrel. The stallion kept going, until he finally tensed and groaned. A new sensation plowed through Twilight's mind as she felt herself being filled with Mac's seed. Her own orgasm flared and she saw stars.

"More..." she panted in the odd everytone of a Changeling...

"Twi... ah can't..."

"MORE!" she shouted and her horn flared, forcing his organ back into rigidity and squeezing his prostate. His balls were worked over as well and he moaned as he felt himself cum again. He couldn't stop as he filled Twilight to the brim and beyond, his seed spilling over and splashing onto the grass as she was full.

Finally sated, as there was no more room to put anything inside of her, Twilight let Big Mac go and staggered away as the stallion collapsed against a tree, breathless and stoned on endorphins. She looked herself over. Her carapace was shining in the sunlight and the green sections around her middle had stretched to accommodate the sperm she had extracted from the male. Her insect-like wings fluttered as she smiled and conjured a small mirror to look at herself. It was held in a mostly-purple glow, tinged with green as she looked at her new jagged horn. At least her eyes had stayed the same, minus the new cats-eye pupils.

'Enjoy yourself?'

Surrounding herself with green fire, a none-the-worse for wear Twilight Sparkle smiled and nuzzled up against Big Mac, casting the memory modification spell, 'Very much, though I'm sorry I lost control... I didn't mean to do that too him...'

'With time comes control. We'll work on that while you build your hive. You need someplace to keep all these drones you're going to lay.'

'First I'm going to use this boost of power to clean up this mess and finish Mac's work and my own.' The mare thought to her mental companion before smiling once more at the now-sleeping stallion and walking off into the orchard.

Author's Note

Oh dear Celestia this is terrible, but, here you are. Twimac clop. Terrible, terrible, clop, but clop nonetheless. You have no idea how embarrassed this makes me. Why does writing pony sex make me feel like I'm revealing the darkest secrets of my psyche on national TV?