This Is For Science, Tilly.

Here's the great part; when I push the IV needle through the pale skin inside her elbow, my cock is already deep up her ass. She's just begun to catch her breath from my single impaling thrust, when the needle's prick comes without warning. This is the part I love-- I feel her ass contract tightly from the pain, but she's well-disciplined now, and doesn't even flinch. Her name is Dr. Linsmuir, but I call her Tilly when we conduct our experiments. She's the new resident; I've only ever had one before who was this cooperative, but he was a boy, and I prefer girls. He was a keen student, and very dedicated to science, but Tilly may be more dedicated still.

I feel her asshole quiver and relax as the mild cocktail of ketamine and valium surges up through her carotid artery and penetrates her blood-brain barrier. She's facing me, her legs high in the stirrups. Her dark eye-lids go half-mast as I thrust in and out of her ass, lubed up by the slick run-off from from her cunt. An animal moan, and all her golden mulatto skin rises in goose bumps; her vulva, which I've yet to touch, opens out red and shiny from her thick black bush.

From a stand next to me, I take the breathing apparatus and place it over her nose. It is attached to a tube of nitrous oxide, which will mix with the air she breaths through her nose in the proportion I specify on the instrument panel.

"Comfortable, Tilly?" I ask.

"Yes, Dr. Reynolds."

I pull my dick out of her ass and wipe it off with a hot towel. In place of my it, I shove an 8" stainless steel dildo completely in, and at the same time, alter the composition of gas/oxygen from 0 to 15%. The val/ket cocktail keeps Tilly from lurching around and pulling out the IV or breathing too fast and hyperventilating; pure sexual stimulation makes her pupils dilate.

Her thighs begin a low-frequency quiver. The dildo starts to slide out of her ass, but I push it back in and secure it with a single strip of medical tape. Lower the gas ratio to 5%, I walk up to the head of the examining table, and with a finger on her chin I turn her head to the side. She opens her mouth, parts her large red lips, and just her tongue the slightest bit between her teeth. Grabbing her soft, kinky hair by the scruff with my right hand, I pry open her jaw with my left thumb and thrust my cock past her teeth, fucking her mouth at my liberty.

On one of the instruments to which she is attached, there is a number displaying the oxygen concentration in her blood. I push a button a few times, and raise the nitrous feed to 60%, while I start forcing the head of cock past her tonsils and inter her warm throat. I fuck her throat while she slowly lets out the last breath she took and moans, sending extraordinary waves of pleasure through my parasympathetic nervous system. Her jaw starts to tighten—oxygen deprivation is just beginning to set in—and her adrenaline is beginning to fend off the dissociative drugs coursing into her soft right arm. I lower the nitrous, and watch the oxygen saturation in her blood rise to normal levels.

There she is, dildo in her ass, arms and legs strapped naked against the examining table's cold synthetic leather. I dial down the nitrous to zero, let her bloodstream clear, walk around the table to take a close look at her cunt; it's pulsing, purple-orange, her clit contracting and drawing up into a shiny pink bullet. Her juices ooze out of her hole, soak the thick hair running down between her large round asscheeks; they soak the medical tape holding the massive steel dildo in her ass. I pull off the tape, and the dildo slowly slides out, leaving her gaping asshole to flinch against the shock of cold air (we keep it surgery temperature in the lab).

After making some notes on a chart, I walk back around to Tilly's face, and I shove my cock in her mouth again while turning up the nitrous to 100% for 25 seconds. I do this twice more, giving her break periods of 10 seconds. A third time, I reach down and gently brush Tilly's clitoris.

Tilly moans loudly, making my cock buzz from tip to prostate. She cums ferociously but neither bucks nor thrashes; her body remains relaxed while all sensation is channeled and focused into her clitoral body.

I force my cock into her throat and feel her generous lips tighten around its base. Her oxygen saturation level go from green to yellow, and just as it's getting to red, I pulling out of her throat and spray hot cum into her mouth, her lips wrapping it behind the head.

I go soft, and Tilly's jaw goes slack, eyes faraway. As my cum dribbles out of her mouth and down her chin, I remember to turn off the nitrous feed before she loses consciousness.

At this point, I grab a couple of swabs, and take the samples of secretions and blood. I will analyze these later with the assistance of Doctor Linsmuir. I am an endocrinologist researching various kinds of sexual hormones, of which the human body releases an enormous variety whose function is still largely unknown. While institutional funding is hard to secure because of the nature of the experiments, I have managed to find a number of interested private and corporate patrons. Good help, however, is harder to find, and I am very pleased with Dr. Mathilda Linsmuir.

"Thank you for your cooperation, Tilly. That was superb."

"Ahma..guhwu..sho," she mumbles, her mind still in an orbit of transcendent pleasure.

At this point, I figure she deserves a little extra credit for her performance. I shall have quite a sample to analyze from this experiment. I dial the nitrous up to 15%, get on my kness between her glorious legs, and lap furiously at her swollen clit, giving her orgasm after orgasm.

Here, in our private, soundproof laboratory, Tilly can wail and yowl with pleasure while I eat her pussy fast and sloppy-like, pushing the dildo once again into her ass. Her cunt tastes spicy and strong, and her continued spurting coats my face. Yes, she was an excellent candidate. Perhaps I will ask to keep her on when her residency is through; hmm-- perhaps I should solicit her for an experimental design.

In the meantime, I draw the IV out of her, and lead her naked and stumbling down the hall to the breakroom, where I lay her face-down on the couch and fuck her ass hard until we both come again.

I leave her on that couch, gently rolling back and forth and hugging herself, smiling distractedly while her ass oozes my cum over the vinyl upholstery, but the next morning, she's in the lab, sharp-eyed and professional, ready to do some biomolecular analysis. Definitely a keeper.