Cutie Mark Crusaders, Spell Testers!

Sweetie shuffled on her hooves as Apple Bloom returned to her spot by the shelf with her and Scootaloo, knowing what would come next. Though she was happy for the delay, and the show, as she too was enraptured by the performance the pair beside her was putting on. She jumped as Twilight called once more for her attention "Sweetie Belle? Come on up, it's getting late."

With a nervous look in her eyes, Sweetie Belle walked up to the adjustable bar and put her hooves up. Noticing they rested above her head, Twilight brought the bar down a couple notches to make her more comfortable. With that, she was prepared to complete the final spell of the evening, which she was more than grateful for as this spell proved to be quite taxing. Most spells tended to be on the first draft.

Twilight had gotten more than enough practice by now to speed the spell along and have them on their way by sundown. Once she centered her focus on the biological signature, Sweetie's balls dropped down almost immediately. Though, despite forming quickly, they took quite a while to actually grow, and didn't quite make it to matching Scootaloo's. Wispy snow white fur over the pink flesh of her scrotum lent it a pearly pastel hue, fitting for the little marbles within.

Next as always came the penis itself, a bubblegum pink rod proudly emerging from a dull gray sheath. It began fairly thick, just thicker than Scootaloo's, and started to grow inch by inch as usual. However, as Twilight worked she struggled to get the features to come through. The medial ring would only grow to a dull ridge, and the flare rounded forward and outward more than the others, but didn't add much width.

Then, without warning, the magic fizzled out in a shower of lavender sparks. Sweetie squeaked as an electric vibration ran through her new appendage. It slapped against her belly, or rather, right between her flat breasts. The magical equivalent of a short circuit rebounded and sent shudders down Twilight's body as well. She furrowed her brow. "Hrm, that's odd." She said to nobody in particular. She tried again, but still the magic refused to finish the job. It fizzled once more sending an electrical pulse down the length of the shaft, which caused Sweetie Belle's knees to buckle and a small squirt of fluid to spray from her pussy.

Twilight started to flip through her papers, checking over her formulas and scrawling down notes while muttering to herself. "Am I low on energy? Is she resisting the spell? Is she too young? Think, Sparkle..."

"Wh... what's wrong?" Sweetie asked with shaky breath, concerned for what magical mishap may have befallen her this time. Her concerns weren't helped by the unmistakable sound of Scootaloo - still on the floor but taking a break from servicing A.B. to take a peek - snickering behind her.

"Oh nothing! Nothing. These results are just a bit uh... Underwhelming." Twilight said, quickly turning her attention to the filly to save face. She explained the situation as she brought a mirror over for her to see. "It's not bad for a foal, let alone a filly obviously, just not what I was expecting. Perhaps you're a late bloomer, or your lineage runs a bit small, or your femininity made the spell not take as well. Like I said, it does take into account the target's desires as well." Twilight rambled with a nervous energy, trying to cheer up the filly and brainstorm possibilities to prevent that from happening again. "Regardless, I'll be sure to make the spell compatible with a more basic growth spell in the next iteration"

As she gazed at her reflection, Sweetie's mouth dropped open to be quickly covered by a hoof. Sure enough, sitting tight to her body was a downright miniscule pair of balls, no larger than a couple of gumballs. Similarly the little speck of pink she could see was comparable to a fun-sized candy bar. Even Button Mash, who she certainly didn't get with for his meat, was slightly larger than her. She didn't start the day wanting this, and she knew it was temporary, but she still came out of it disappointed. A deep blush crossed her face, and she tucked her tail to hide her shame from her friends. Its well conditioned hairs tickled both her female and male anatomy, forcing meek moans past her lips.

Twilight noticed Sweetie's discomfort and tried to be assuring. "Oh, it's nothing to be ashamed of Sweetie Belle! It works all the same, I would imagine." Despite her best efforts, though, she struggled to meet Sweetie in the eyes with the display just over her shoulders. 'Why should they get to have all the fun?' She thought. Scootaloo's hypnotic musk and Apple Bloom's stunning size had really done a number on her, and it was getting harder to hide. "Why don't we find out?" She asked, as she slithered down below Sweetie's belly and popped the petite pink popsicle into her mouth.

Sweetie Belle jolted with a yelp. She was no virgin, but this felt far different than she could have imagined. The sensation of being engulfed in something so warm and wet was nearly as good as the sensation of being filled. And her size, while disappointing, made the plush tongue gliding side to side underneath her filly dick feel even bigger and more pillowy. Twilight expertly sucked on the member like she'd studied and practiced, taking it to the sheath with ease. Plenty of room to spare, she went further, engulfing the balls into her mouth as well. Some gentle nibbles and prideful hums later, Sweetie Belle was quivering up a storm and struggling to stay grounded. Her clit winked uncontrollably and Twilight tasted the first drops of her salty reward. It wasn't long before she finally came, and her hind hooves lifted up off the floor, leaving her supported only by the bar. Her eyes shut tight and mouth opened wide, but no sound emerged but a raspy gasp. Down lower, though, her legs twitched at either side of Twilight's head, and juices from her marehood ran down her legs in torrents. Twilight moaned, finally satisfied to get the cum she so craved. After all this her own plum-colored shaft was raring to go - she'd have to take care of that later before getting rid of it.

Across the room, Scootaloo was kneading Apple Bloom's sack with her hind hooves while using her front hooves to stroke it up and down, in time with the pace of her simultaneously humping it. She held her mouth open and was trying her best to catch the near constant stream of pre, but some inevitably fell on her face and became caked in her mane. To the untrained eye one might think she was worshipping it, but they were just two kids exploring their bodies and having fun.

"Buck, Ah'm gunna..." Apple Bloom's accent heightened in the moments before her orgasm. Meanwhile, with her mouth still full of Sweetie seed, Twilight's eyes shot open in shock.

"Mmh! Uh-uh!" Twilight exclaimed through a mouthful of cum. She was so preoccupied with Sweetie Belle she'd forgotten the ticking time bomb that was about to repaint the library at any second. Her horn's magic flickered to life and shot a bolt straight for the ropes of milky filly cream shooting from Apple Bloom and Scootaloo's cocks, desperate to save the floor from a sticky demise. Two orbs of energy collected the cum from each of them as they spurted out in tandem. They finished shortly, with Apple Bloom lasting a fair bit longer until she collapsed onto her spent partner, whose dick remained at attention despite all odds.

Twilight drifted the magenta orbs, now full of swirling white goo, over to the table and poured them carefully into containers. Scootaloo's went into a second vial, while Apple Bloom's required two beakers. Sweetie Belle's, she reluctantly spat into another test tube. She hoped the cross contamination with her saliva wouldn't interfere with... whatever it was she was planning on doing with those samples. She realized now she had no plan for them, but she could always think of something fun if there was nothing to research them for.

Sweetie Belle finally returned to her place with the other two newly christened futa fillies. As much as she hated to admit it, the release did wonders for her mood, easing her anxieties immediately. And the other two Crusaders were too worn out to keep teasing her, even if they wanted to. Still though, this whole day had been a bit too weird for her liking, and she was eager to get back to normal.