Twilight's Science Class

Twilight knew how to get Rainbow Dash to her lab-it was simple. Appeal to her pride, simply asking her to come for physical testing as a 'prime pegasus specimen.' As much as Rainbow's pride had improved to not be a huge hazard, that would still stroke her enough to turn up.

Twilight trotted around her lab to set up her device-a pegasus device, if you will. What was essentially a bondage harness hung from the ceiling, magically enchanted to read vitals...and keep the wings strapped down, comfortably at least. Under it, was a simple treadmill, Twilight planning on asking Rainbow to run on it. She knew even Rainbow would be suspicious of asking a pegasus to run, so planned on telling her it was simply to gather ALL data she could. Which was technically true, anyway.

She levitated more notebooks and quills and ink, making sure she had enough as well as spares, just in case. She had planned for everything in her anxiety...except one.

Rainbow came flying down the stairs to the lab as asked, but Applejack trotted after her. "Hay egghead! I told AJ about this, and she wanted to come see! And participate, not that she'll be as awesome as me!"

Twilight looked crestfallen, "Aw, Rainbow...I didn't want too many to know about this yet!" "Hahah, oh twi. Want whatever you're doing to be perfect first, huh?" "Well....yes...but it's okay! I did want to ask AJ eventually too, to represent earth ponies! Would you?" she asked.

AJ looked at the contraption, "Well I can't rightly say I understand what this is or why-" "To record an accurate and recent assessment of pony types!" "Uh...oh! Like how we record new and old apple variations?" "Exactly! Now, to start with...you both need to run on the treadmill," she explained her reasoning behind it, both agreeing.

They got strapped in, Twilight standing in front of a screen to the side of them. She used magic to manipulate it, the treadmill beginning at a walk. "I know it's slow, but I need to record how your vitals increase as the speed does-don't worry, I know you fillies want it fast, and it'll get there!" she assured them, the pair seeming happy with that.

As promised, the treadmill picked up slowly, and in a bit they were both running. "Alright girls, here comes the sprint!" Twilight warned, as it did indeed pick up to an all out sprint. Rainbow was struggling already, despite rather good endurance. "H-hay, Twi...I gotta..." "Oh, Rainbow..."

Twilight pressed a button on the screen, doors opening in the floor, revealing an angled downward cheese-grater, apparently, at a huge size. Pony sized, even. "That's disappointing. But I'll get all the data I need and more, your death won't be in vain!" "Wha....TWI THIS ISN'T FUNNY! WE ALREADY DEALT WITH UNFUNNY PRANKS!" "Science isn't meant to be funny!" She admonished. "Now. The speed you're at, if you slip, you'll be catapulted into this special metal board. You'll be sliced a fair amount, and I'll see how you react to stress in various ways! The same does apply to you, Applejack, but I expect someone with your physical work and stature to last much longer than a career flyer. ...I'm sorry. I know...I know this is scary-i need that data too-but the numbing agents on the board mean you won't feel it for long. Just...long enough. I really am sorry-but this...this needs to be done." It sounded more like she was convincing herself than her helpless friends.

Rainbow gritted her teeth, crying in pain and fear. Applejack looked at her, terror for her friend in her eyes. She gritted her teeth, looking forward, and leapt. She planned on saving Rainbow and stopping Twilight, but this was a possibility she'd seen. As soon as AJ leapt, the harness yanked her into the air. Her strong legs meant nothing in open air with nothing to brace or kick against. Rainbow wailed, knowing she wasn't strong enough to leap like that, even if the harness wouldn't yank her up.

"Oh Applejack...Even now you want to save a friend...But I have a special idea in mind for you," she smiled wetly. "You'll both be a part of science! Isn't that wonderful? All our friends will!" "Y-yall better not touch Applebloom or I swear-" "Of course not. A minor can't be considered for this sort of science. Besides, Scootaloo is of much more interest with her underdeveloped wings. I always wondered what did that, the poor dove." "P-plee-eh-heee-eze! Don't h-hurt Sco..."

Twilight tapped her hoof, before sighing. "Alright, I'll give you that last wish. I will not use Scootaloo for science, pinkie promise." Twilight wasn't sure if she could have done that anyway, not like she was doing to her friends. Rainbow sobbed in relief, but it was too much. She stumbled, hitting the tread and being flung back and down the grater, screaming as the grooves tore flesh and muscle from her body. Blood sprayed out from her body as she scrambled to climb up or even just halt her ripping journey down. She finally came to a stop at the end, wheezing in pain.

Rainbows hooves, back and front, were worn down to nubs at her leg bones, her chest skinned down to rib cage and sternum. In fact, most of her skin on her front was in tatters. The harness had survived, if just barely. Twilight raised her out of it, the harness lasting just enough to get her out of the range as the doors closed above the grater.

She smiled, even as the harness snapped, dumping Rainbow on her front, who howled in agony, her limbs convulsing and adding to her misery. Twilight strolled over to her, leaning down. "You know, I keep saying it's for science, and it is! But...I can't deny...how wet this makes me, to basically betray you and use you...make you hurt, die...I think I might be sick. Possessed, even...I know I should get help. Stop myself from hurting others, but I just...I need to finish this, and...seeing you like this...it's so...erotic. No one but AJ and I have seen so much of you, and she can't see much from where she is..." she whispered, casting a spell and growing a heavy sheath and balls with a shiver.

Rainbow looked confused, then horrified as Twilight rubbed her chubbing sheath against Rainbow's rear end. "Mmmh...You'll numb soon, so you...don't mind me having my fun, do you?" Rainbow writhed, "I do mind! Stop it!" She tried to kick her off, only to cry out as the spasming hurt her shredded parts. It was going numb, at least, and part of Rainbow marveled at how much more that would have hurt without it.

Twilight's mare meat spilled out, right into Rainbow's meat wallet. Twi churred, going to the hilt. "Fuck, Rainbow...so good...so tight, so hot..." She rolled her hips, leaning over to kiss her tenderly, a long, deep kiss. "I love you...I love all of my friends...I love having this last, romantic moment with you all..." Rainbow just gasped in reply, eyes dulling slowly. Even if she could respond, what could she say to that?

Twilight fucked her harder, reveling in the starting death spasms. "R-rainbow..." it was somehow erotic and romantic. No one else would ever feel this-her last moments, making love as she passed. She rolled Dash over, carefully, despite knowing the numbing agent and being so close to death meant Dash would feel next to nothing. She could SEE her cock stretching out the tunnel, hitting the cervix...it was too much.

She came, bloating up the dead womb with the magisperm, visible through the skin.

She pulled out with a sigh, cum dripping down RD's thighs. Twilight looked up at AJ, smiling, almost apologetic. "Now...I have an idea for you,"