Heat in a Bottle

Big Mac bent beneath the doorway into Ponyville general. All attention turned to him as he smiled nervously back at them. In his hand was a bag, and inside the bag was one of his remaining bottles of the concoction. He walked up to the counter and said, “My sister scheduled an appointment with Nurse Redheart?”

The nurse working the station took a sniff towards Big Mac and recoiled from the sweat he had collected over a hard day’s work. Plugging her nose, she pointed down a hall. “She’s waiting for you. Room 107.”

Big Mac sighed and he started heading through the hospital. He had meant to take a shower, but the plow had broken earlier today and fixing it had taken much longer than he had wanted. He lifted an arm and recoiled at his own stench. He then opened the door and stopped the inner groan he had whenever he saw Nurse Redheart.

She turned to him with her normal stern expression. She wore her nurse’s outfit which hugged her curves a little too well. The skirt was so short that the cutie mark of a red cross with hearts at each corner was easily visible on her thigh and allowed full view of her long white legs. Big Mac looked away from the tight top that outlined her massive rack and left little to the imagination. “None of that today Big Mac. Now get undressed.”

He turned back to her as his jaw went slack. Nurse Redheart rolled her eyes. “I’m keeping this on so as not to skew the results by being in extra provocative clothing. However, if we are to test this properly, you should be in a patient’s robe in case of side effects that may cause certain part to, er, grow. Understood?”

Big Mac reluctantly nodded and Nurse Redheart turned away from him. “Um, shouldn’t you leave?”

Slam. He turned to the door and swallowed hard as he realized someone must have put something heavy against it. Nurse Redheart replied to the sound with a terse, “Neither one of us is allowed to leave.” Her tone softened. “I don’t like this Big Mac, but the test would fail if I ran after one gulp of this stuff. Please understand and…” She was silent for a few moments, but then picked up a clipboard.

“Unlike popular opinion, mares do not have to be in heat to be aroused. However, we don’t think about it very often, and it takes much more than with stallions to get off or be turned on. Couples that are naked together may have sex because of love, and with enough heavy petting a mare will start to get off. However, we are taught to repress sexual fantasies, and that idea will be our baseline for this experiment.”

“Nurse Redheart, shouldn’t we not be doing this on ourselves? Or together?”

Nurse Redheart turned around and scowled at him. “Normally we would examine the potion for it’s magical and medical properties and experiment on other animals. However, we must assume this was made for equine anatomy, and with the normal age of a mature mare going into heat being twenty, time is of the essence so we can know what repercussions may have happened to your sister.”

Big Mac nodded and sat down. Nurse Redheart turned just in time to avoid being flashed. “Please stand. You are too tall to wear a robe that small.”

Big Mac thanked the fact that his coat was red as he stood back up. “I’m sorry. One of the problems being so tall.”

Redheart sighed and put a hand on his chest. She had talked to him many times about the fact that he was about a foot and a half taller than any mare in Ponyville. She had always found the height interesting, at least until two years ago. At the thought she withdrew her hand and picked up Big Mac’s bag.

“Alright, we’ll be doing this in increments. From what your sister told me, a full bottle will turn a mare almost to a sex driven monster, unparalleled by any other aphrodisiac, correct?” She watched as Big Mac nodded. “Alright then, we will both be only having half of the bottle today then.”

“Me too?”

Redheart gave him his cup as she looked down at the green liquid in her own. “We may as well get testing stallions out of the way at the same time.”

Big Mac put a hand over Redheart’s cup. “Then it makes less sense that we are together.”

Redheart sighed. “I’m the only person on staff willing to do this. Besides, I need something to fantasize about otherwise I may not be affected by the early stages at all.” She paused as Big Mac’s eyes widened and downed her glass before saying, “Besides, you need something to fuck in case it drives you insane with lust.”

Big Mac looked down at Redheart as she said that. She turned away and pulled out a pen and paper to jot down preliminary notes. She pulled at her skirt, as if trying to hide her rear, something he had never seen her do before. He downed the glass, hoping he didn’t have to rape her.

Redheart looked back at Big Mac as she had managed to shove the sudden thought of fucking him out of her head. I’m not feeling anything really in my crotch yet. She bit her lip as she thought about what could be feeling down there. However, there is definitely an increase in my fantasies and the effects they have on me.

Big Mac let out a groan. “I think I’m feeling something. It feels like my balls are tightening.”

Nurse Redheart and wrote on the pad possible increase in sperm count and production. She turned back to him, finding it rather easy to keep her fire in check. However, that was to be expected of an older mare like herself. She needed stimulus to actually check the potency. She thought back to what Cheerilee had told her when getting her hips checked two years ago.

“What is the best part of my body? And please be specific.”

Big Mac looked up and simply stared at her for a few moments before clenching his jaw. “Your smile.”

She scowled and said, “I don’t like lies. Now come on, say my tits.”

Big Mac bit into his lip, but couldn’t deny that that was where his eyes were glued. “They’re nice, but your smile brings joy. I’ve seen you make sick fillies and colts forget about their pain as you played with them. Not to mention the gentle calm it brings your older patients as death closes on them. I only wish we adults weren’t so annoying to you.”

She stiffened as she thought of how much of an actual interest he had to have taken to her through the years to notice all of that. How he had noticed so much about her job, while so many of her older patients simply thought she was bitter. Then again, they usually act more like children then the fillies. She glanced back at Big Mac and blushed while remembering the pleasant visits he used to have with her.

Stop it! She took a deep breath before announcing, “Time to take another drink.” She giggled as Big Mac raised his glass.

“To old friends.” Big Mac shotgunned it down. He marvelled at the fact that it still tasted like a freshly picked apple. However, his mind was soon distracted as his the erection he had been fighting started to win. He slammed an arm over his hips and winced at the impact.

Red Heart noticed it and felt her crotch finally react to the potion’s effects. She bit into her lip as a warmth spread through her body. It then grew when she realized why Big Mac would be covering himself up like this. She shakily wrote, One third: Forced arousal from little to no stimuli, forced erection. She glanced back and forced herself to calm down.

Redheart sympathized with Big Mac as he tried to keep it from being quite so obvious, but he wasn’t a great actor. “If it might relieve you, you could turn around and attempt jacking off. May provide data on early level stamina and cum production.”

He nodded and turned around. He lifted the gown and attempted to forget about Redheart being there. However, it was her, or Apple Bloom on his mind at the moment. Doesn’t help that I felt so guilty that I didn’t take care of myself yesterday.

Redheart stifled a gasp as Big Mac’s unbelievably toned ass pointed in her direction. She swallowed hard and tried to accept that this was his body, nothing more. However, the desire in her was stoked by thoughts of what that ass might feel like in her hands.

Fap, fap, fap.

Her heart almost stopped as she listened intently. No. That is the pinnacle of what is wrong with penises. Stop thin– “Unn.” She glanced down at her chest where her hands were lightly gripping herself. They’re just confined and need release. I’ve only had a third of the potion, I’m fine.

She undid the first three buttons of her shirt and spread it wide open. However, her wrap of a bra kept her chest tight. She ripped off the cloth and sighed to herself while continuing to tell herself that the lust was dying.

Big Mac gave one last grunt as he came all over the bed he would have normally been sitting on. He breathed heavily as he looked down upon the excessively large amount of cum that lay before him. “You may want to see this Nurse.”

Redheart shakily stood and glanced around Big Mac. She swallowed as she saw the cum, and her groin whined in need as the thought of her drinking that much came to mind. “Alright, third drink. Now!”

She had them down it immediately, and felt a tingle run across her body. She now wanted all of it off, all of it. She slowly moved a hand down to the pad and barely wrote, Sensitivity. She took a deep breath in and smelled the stench that came off of Big Mac. However, it now smelled wonderful.

She turned to Big Mac who was just happy that it didn’t seem to do anything this time. He quickly lost that happiness as Redheart walked very close to him. “Eeyup?”

“When was your last check up?”

Big Mac gave her a nervous grin as beads of sweat came down his face. “Six months ago, but an apple a day right?”

Redheart smiled at him. “I may as well make absolutely certain that you are right.”

Big Mac tried to stop as she squatted and moved the gown to the side. She stared at the mare breaking eleven inches. The cock that made Cheerilee not be able to walk for a week. The cock that caused her to want more She looked up at Big Mac and gave him an eager smile. “Please fuck me. I don’t think I can take much more.”

“Are you certain?”

Redheart laid on the ground and spread her legs, revealing a pair of glistening black panties. “Eeyup.”

Big Mac couldn’t take anymore and tore off the gown before gripping her breasts. He used one hand to quickly move the slick fabric from his path, and then slowly put his cock in. He knew he couldn’t go too fast, but the folds clung to him and the moans just drove him further and further into his need.

Redheart gasped as she tried to breath between lewd moans. She loved every minute of the screw, even when Big Mac dramatically increased the pace after his first thrust. With each collision with the back of her pussy, Big Mac came closer and closer to hilting her.

He lowered himself while his cock continued to throb and pulse within the mare. He collapsed on top of her as his hooves lost purchase on the tile floor, driving his dick harder then his held back thrusts could. Immediately the walls of the pussy tightened around his penis like a vice. He continued almost unimpeded, but still found that release alluded him. Finally with her second orgasm grabbing his cock did he give her his load. Thick spurts of cum poured out of her as he deposited his load deep within her.

The two laid there for a few moments, staring into each other’s eyes as if they hadn’t done this as part of an experiment. Redheart attempted to nuzzle into his chest, but gasped as his cock became hard within her. This time, Big Mac was in more control and slowly thrusted into her. Each thrust flooded both of them with pleasure. Pleasure Redheart was quickly learning to adore.

The thrusts gave Big Mac more time to enjoy his lover’s body this time. The soft ass that most complained was hard. The bouncing tits that now entranced him as he moved in time with their motion. And finally, a lustful smile that begged to be fed.

Redheart was surprised when he leaned down. However, the moment his lips were in range she lunged and pulled him down into it. She didn’t care about the shy tongue as she tried all she could to continue the kiss. Pleasure and happiness flooded through her with each kiss, locked in a deep embrace that was only ruined by the smacking of his balls against her.

Finally, the wave that had been building in Redheart released again. This time they were locked in a deep embrace, and Big Mac slowly released his load as he pulled out of Redheart who curled up in the fetal position, gently shaking. He breathed in deeply, but knew the already rock hard cock on him wasn’t going anywhere.

Redheart turned around and asked, “Are you leaving?”

He scratched his head. “Only if you want me to.”

“Hold me, please?”

Big Mac knelt down before gently scooping her up and putting her on his chest. He laid on the pool of cum on the bed, ignoring his massive hard on for her.

======+++++======

It was this tender embrace and possible loving moment that now kept Redheart up as her hands gently stroked her pussy. She couldn’t get rid of the rogue thoughts, no matter how much she knew better. If I want to continue these tests and not lose myself to that kind man, I’m gonna need help. Royal help.