Rainbow took a swig of water as she watched her track and field team from the school bleachers. The sun was just beginning to touch the horizon, and the crisp autumn breeze grew chillier by the minute. Not that Rainbow was terribly worried about that; she'll be plenty warm soon.

Ever since she became team captain for almost every sport Canterlot High offered, Rainbow was tempted to take many of her teammates behind the bleachers for a little 'special exercise'. She could never sneak any of them away from the coaches though, and by the time practice had ended most of the others were too tired to even entertain Rainbow's advances. Sure, one of her friends was usually willing to help her take the edge off, but it just wasn't enough. All of their sexual appetites had grown too large for each other to handle.

That was before they even discovered their magic cocks. Their libido had increased tenfold, and their hunger even more so. Rainbow wouldn't be satisfied with just a fling with one of her teammates; her new goal was to turn each and every one of her teams into the greatest sex athletes she could ever ask for.

Thankfully, now that they had the principals under their thumb, Sunset had them convince the sports coaches to leave Rainbow in charge of practices, though she would've also been fine if she had to fuck the coaches into submission herself. This left her with the perfect opportunity to go wild, though even she knew it still wouldn't be that simple. Sunset had already advised each of them that they seek out a 'second-in-command' as she like to put it. Rainbow had the perfect idea of who she should get into her graces: Spitfire.

If only it were that easy. Spitfire was dedicated, stubborn and more than a bit antisocial. She'd rib with her teammates, but was rarely ever seen actually hanging out with other students outside of school, and usually brushes off any offers with barely a word said. Rainbow knew she was going to have to work her way up to getting Spitfire on her side.

None of that was why she was out here today. No, today was a day to relish in their freedom to fuck whoever they wanted, and Rainbow had a very particular taste. Before, she preferred the girls who had a lean physique like hers, spending most of her off time with Applejack in bed. Once she gained her dick, though, she actually came to prefer Fluttershy and busty girls like her whenever she decided to whip that little trick out, and her track team this year was full of girls like that.

Her eyes passed over each runner as they rounded the track near her seat, internally debating which of them she was going to pull aside first. Fleetfoot would probably be the smartest choice; she was the only girl anyone had seen Spitfire get close to, and having her in on the plan would make Spitfire easier to reel in. Vapor Trail was really cute and trained like crazy; she could probably satisfy her for hours. Angel Wings reminded her a lot of Fluttershy, and Rainbow would be lying to herself if she didn't admit she loved having the demure pegasus in her lap.

Derpy was just hotter than all of them.

Sure, she wasn't the most athletic of the team, being the last to cross the imaginary lap line sitting in front of Rainbow's vision, but she was even more determined than Vapor to prove she deserved a place among them, and Rainbow admired that kind of dedication. She also admired Derpy's massive jugs bounding freely with every step; she was certain the girl never wore a bra, not that she'd be able to fit in one anyway. Her ass wasn't as large, but still very eye-catching, rippling slightly as Derpy got her second (third maybe?) wind and took off to catch up with the rest of her classmates.

Having settled on her decision, Rainbow silently waited for the team to make there way back around to her bleacher before blowing her whistle. "Alright girls, that's enough for today. Everyone behind Angel will start with five laps tomorrow, the rest of you will start working with the vaults. Get plenty of rest and meet up here right after school," she called out to everyone.

As most of the crowd dispersed to go home, Derpy finally made her way up to what was left of the group. "Sorry, Coach Rainbow, did I miss anything?" she sighed through her pants and heavy gulps of breath.

"Woah, there, I think you should sit down for a moment," Rainbow suggested as she got the exhausted girl a cup of water. "Look, I really do appreciate you trying so hard, but don't push yourself too far beyond your limits. You're gonna hurt yourself if you don't listen when your body says it's had enough."

"I'm fine, really," Derpy lied before downing the entire cup of water. "I can keep going if I need to."

Rainbow briefly began to second-guess her plan, genuinely concerned for Derpy's well being before she settled on a compromise. "Well, if there's something you need to work on, I think it's your cardio. You need better breath support and circulation before we worry about how fast you're going. Tell you what, if you've got a little extra time tonight, I've got an exercise we can try to help boost you up a little."

Derpy rushed to agree, but Rainbow placed her finger against her lips before she got a word out. "But, I don't want to see you at tomorrow's practice, okay? I want you to go home and rest, let the exercise you've already done have a chance to take effect instead of running yourself ragged. Do we have a deal?"

"Rainbow, I shouldn't miss out on any-"

"Uhp-pup-pup," Rainbow interrupted. "Resting is just as important as exercising. You do this, and I can guarantee in a couple days you'll be feeling and doing a lot better."

Rainbow watched as Derpy sat in contemplation, clearly fighting with herself on what she should do. She knew Derpy trusted her judgement, but the girl was deadset on proving herself an equal to her peers, and anything less than giving all of her effort all of the time usually wouldn't suffice. This wouldn't be the first time Rainbow had to try and reel her in, but she had a feeling Derpy would be more agreeable with this extra 'training'.

"Well... if you really think it's best for me, I suppose we have a- EEP!" Derpy's agreement was cut off as Rainbow shoved her hand beneath the silver girl's shirt, groping the bare mounds that hid underneath.

"Mmm, I was right," Rainbow gloated, her voice dropping to a low husk as she leaned in closer to the helpless girl in front of her. "No bra. Guess these marshmallows are just too much to contain, huh? That's okay, I'd rather not waste any time." She tightened her grip, digging her fingers into the globes of flesh and flicking her thumbs across Derpy's quarter-sized nipples. "Fuck, I've been dying to feel these up for ages. They're even softer than I imagined."

Derpy's shocked squeal was quickly replaced by stuttered moans, her thoughts lost to the sudden onslaught of pleasure brought on by Rainbow's vigorous ministrations. She barely had a moment to attempt to collect herself before she felt her shirt lifted away from her breasts, Rainbow eagerly planting her lips on Derpy's left nipple as she kissed and licked her soft skin. Rainbow's tongue was relentless, alternating between coiling around the little nub and pressing it deep into the rest of Derpy's boob.

"Hmm, I wonder if a bra is the only thing you went without," Rainbow wondered aloud as she shifted her hand away from Derpy's tit and slid it underneath her shorts, her fingers being met with the feeling of Derpy's soaked pussy lips. "Seems it wasn't. You were prepared for this, weren't you?" she teased, violently rubbing her fingers against her swollen nether region before plunging two of her digits deep inside, vigorously pumping back and forth and coating her hand in Derpy's fluids.

Derpy writhed in Rainbow's grasp, her legs spasming every time her captain pressed against her pussy's walls. The invading extremities explored each and every corner of her vagina they could, occasionally splitting apart to spread her cunt wide open. Her voice grew more and more strained, slipping into sharp squeaks in between each of her near-deafening moans.

Rainbow relished in every second of their foreplay, though her body grew more and more impatient for its own taste of pleasure. She withdrew her fingers, granting Derpy a brief reprieve as she admitted, "As much as I love playing with this sweet, sweaty body of yours, I think it's about time we get to the real exercise." Within seconds she had discarded her own gym shorts, her magical cock standing proudly in front of Derpy's shocked face. "You ever had one of these before?" she asked playfully. Derpy slowly shook her head, her beady eyes never straying from the dick's pulsating head.

"Don't worry, I'll show you the ropes," Rainbow assured, grabbing Derpy's head by the sides and shoving her cock straight past the grey girl's lips and down her throat. "Damn, your mouth feels like it was just made for fucking," Rainbow commented as she began thrusting, pulling her shaft back until Derpy's lips were softly wrapped around her head before pushing herself back down as far as her cock could reach. Knowing how much Derpy had been gushing from just her fingers, Rainbow imagined her shorts were completely soaked by now, and the mental image spurred her to pick up her face, fervently face fucking her friend as her shaft became coated in precum and saliva.

The sheer pleasure was almost enough to bring Rainbow to climax, but she wasn't done yet. She pulled away from Derpy's mouth with a satisfying pop, pushing her by her shoulders onto the grass beneath the bleachers before yoinking the girl's heavily stained shorts off her legs. Rainbow lined her swollen head up with Derpy's needy pussy, taking only a brief second before hilting her cock in Derpy's cunt as quickly as she had her mouth. If Derpy had any protest, it was swiftly cut off by the loudest moan Rainbow had heard from the girl so far. She didn't really care how loud Derpy got; if somebody else heard, what were they gonna do about it?

Rainbow made it her personal mission to coax just as strong of a scream out of Derpy as many times as she could, mercilessly railing her tight passageway and battering her cockhead against the girl's cervix. Derpy's breasts bounded back and forth in front of her, and as much as she loved to watch them bounce so freely, Rainbow planted her hands firmly against the two mounds so she could watch Derpy's face as she fucked her senseless. She was also able to use her new position for more leverage, putting even more force into each of her thrusts.

Rainbow's efforts paid off in spades, as each of Derpy's moans blended into one continuous wail, hitching slightly each time Rainbow's head kissed her womb. Her juices leaked from her entrance constantly, Rainbow's girth doing little to stem the flow and even spurting more out with each thrust of her hips. Derpy herself was consumed in the throes of her pleasure, her only perception of reality being Rainbow's gratified smile as their minds drowned in a sea of sexual ecstasy.

Rainbow dug her fingers deeper into Derpy's breasts, leaning into her and kneading the two fleshy balloons with all of her body weight. "Fuck, you're body feels so good Derpy," she teased without missing a stride in her ramming. "I'll bet this is the best workout you've ever had. Don't worry, you'll need to do this exercise often if you wanna see some results. I know I won't mind helping you out." Rainbow figured Derpy couldn't really make out much of what she was saying, but there was something about the thin veil of an excuse she was drumming up that turned her on even more.

Rainbow could feel her climax creeping up on her once again. She vaguely recalled Sunset saying something about their magic dicks being sterile, and the idea of pumping Derpy full of her sperm was almost enough for her to let loose right then. Her thrusts grew more and more shallow, driving even more of Derpy's fluids down her thighs. At this point Rainbow wasn't sure if Derpy was just constantly cumming or if this was just how wet she normally got; she loved every second of it either way.

Derpy seemed to catch on to Rainbow's intent, using what little strength she could muster to lift and wrap her legs around Rainbow's waist. The unspoken encouragement was enough to send Rainbow over the edge, letting loose a gargantuan volley of her semen that flooded what little space was left in Derpy's pussy. Rainbow felt Derpy's walls constrict around her shaft, milking her balls for everything they could give as Derpy's own orgasm coursed through her nerves. Her heels dug into Rainbow's back as she desperately tried to force her captain's hips as close to herself as she could.

The moment the last drops of Rainbow's cum left her body, her magic gave out and her cock disappeared, leaving Derpy's pussy wide open and allowing both of heir fluids to flood out and coat the ground beneath them. The sight of Derpy splayed out leaking globs of her cum was just enough to mitigate her frustration at only being able to go one round. Perhaps the one thing she envied of Twilight and Sunset, though she hoped with this exercise things would change for her. It didn't matter right now; she got exactly what she wanted, and she knew it would only get better from here on out.

Speaking of which, "You still with me there Derpy?" she playfully inquired, receiving only a small nod as a response. "Good enough. Like I said, take tomorrow off. Get some rest, and if you do, I'll make sure we can continue this exercise the next time you're here. Sound good?" Another nod. "Good!" Rainbow picked herself up off the ground and gathered her clothes, stopping just before she left to add, "Oh and Derpy, I'm sure I can count on you to help me introduce this exercise to the rest of the team. It'd do wonders for everybody, don't you think?"

Rainbow could see Derpy's body quiver at the thought as she let out a hoarse "Yes, captain,". Mental note: have my toys refer to me as captain while I fuck them. Rainbow's imagination ran wild as she got herself dressed and left for Sunset's apartment to finish herself off. Now that she had Derpy on her side, it was time to start working up the ladder to her ultimate goal, Spitfire.

Oh, this is gonna be fun.

Author's Note

So the plan is for each of the Mane 7/Spike to not only have their own corner of characters at their whim, but a general goal and theme to their plan. Rainbow making sex a full-on afterschool sport, Rarity showing off her new style with a strip club, Fluttershy filling her corner with her new pets, etc. I haven't figured them all out yet (Pinkie, Spike and Applejack especially), but any and all suggestions are welcome. Thank you so much for reading and I hope you enjoy what comes next.