The next morning Marcy was dragged from bed by a strapping Swedish masseuse named Mrs. Swenson, and bullied into eating a breakfast twice the size of the one she usually had.
"Eat it! Eat it all!" Mrs. Swenson ordered. "Dr. Villiers has prescribed each item to increase your strength and stamina for the experiments to come."
"But I'm tired," Marcy complained, "and I ache all over."
"The soreness will be gone by the time you are bathed, massaged, and exercised," the broad-hipped, muscular woman said. "But we have only an hour for all that, so we must hurry."
"Only an hour? What's the rush?"
"Doctor's orders," Mrs. Swenson said. "I do not make the rules around here, I only see that they are carried out. I do not approve of what goes on, but Dr. Villiers is my boss and the pay is good, so I keep my mouth shut and do what I'm told. I advise you to do the same."
"Oh, all right," Marcy sulked, but she let the big woman strip her, and followed instructions to take a hot and then a cold shower. When that was done, Mrs. Swenson lifted her onto a massage table and pummeled and pounded her until her flesh was rosy and tingling, and all her aches and pains were rubbed away.
Dr. Villiers arrived in time to watch as a tightlipped Mrs. Swenson dressed Marcy in long, black net stockings, sheer bikini panties with a zipper from the front to the back of the crotch, and a bra that was merely a display shelf for the lush mounds of her breasts. The doctor took over then, pinching Marcy's nipples into hard peaks and then applying a deep red lipstick to them.
When he was finished, Mrs. Swenson turned the girl around to face a full-length mirror, and Marcy's face flamed as she stared at her reflection. Then the woman brushed her hair until it shone. Could this wanton whore who looked back at her, this tart with the garishly painted tits and underclothes that flaunted her blatant sensuality – could this be the Marcy who had been so prim and proper only yesterday morning? No, it couldn't be! That Marcy wouldn't have permitted her body to be so vulgarly exhibited. That Marcy wouldn't have yielded to the temptation to move her shoulders, and see the brazen globes jiggle. She would not have swished her hips in a suggestive manner that made Dr. Villiers grin and Mrs. Swenson scowl.
"Come along, X-999," Dirk Villiers said, dropping a white, transparent poncho-like garment over the erotic under things. "The Karlows will love you. There's nothing they like better than dressing up for sex games."
Marcy followed him obediently down a long hallway. "Do they – I mean, do they really make love to each other?" she finally found the courage to ask.
"I wouldn't call it 'making love'," Dr. Villiers said. "They fuck each other just as they fuck any other living creature that crosses their path. That is why they make good experimental subjects."
He turned the knob of a door marked Laboratory #2, and entered ahead of Marcy. The Karlows rushed to greet him. Kyle was dressed in a loincloth and headband, and his tanned body glistened with fragrant oil. A copper slave collar was fastened around his neck, and Karla held the other end of the chain attached to it. She was dressed in a flowing Grecian gown that left one shoulder and one high, golden breast bare. Her pretty face was flushed, and in her hand was a small black whip which she had already used, judging from the red welts on her brother's back.
"Dear Dr. Dirk!" Kyle said, and dropped to his knees to kiss the man's feet. The movement caused the loincloth to fail to one side, and Marcy sucked in her breath at the sight of the strong young cock in a state of throbbing erection.
"We have been heightening our sexual sensitivity with an extemporaneous playlet," Karla explained. "I am the cruel mistress, and Kyle is my worshipping slave. He crawls to me and begs permission to lap at my golden fountain as he revels in the pain from the whip."
Kyle's finger ran caressingly up the doctor's legs, and attempted to fondle his prick. "Perhaps our beloved experimenter would care to share our pleasure."
Villiers backed away, shaking his head. "No, not this time. I must observe and take notes."
Karla pouted, and Kyle's red mouth puckered up as though he were about to cry. Watching, Marcy thought how like children they were. Spoiled brats, really, who had been given so much all their lives that they couldn't stand being denied instant gratification of any desire.
Karla stamped her foot. "Why can't you be with us? You know we'd do anything for you! Why do you repay our devotion with indifference?"
"I repay it with scientific interest," Dr. Villiers said calmly. "I have brought the new experimental animal to you. I wish you to teach her the significance of troilistic lust, while I observe from the recording station."
Two pairs of eyes swung to Marcy, and she shivered slightly under their appraising stare. Would they accept or reject her? She didn't know which would be worse.
Karla's pout slowly turned into a sly smile, and her tiny red tongue flicked over her lower lip, while her free hand moved to her bare breast, and began fondling the extraordinarily large nipple.
Still kneeling, Kyle lifted his head, and his expression changed until it was almost an exact duplicate of his sister's. One of his hands moved just openly to erect his prick, and began stroking it.
"Yes, Doctor Dirk, we will be happy to teach your newest subject our games," Kyle said. "Won't we, Karla darling?"
"Oh, yes," Karla agreed enthusiastically. "And look, brother, they dressed her all up sexy for us."
"Her name is Marcy McCall, and her laboratory number is X-999," Dr. Villiers said. "Take good care of her, she cost a lot of money." He strode quickly to a door on the other side of the room, and went through it. Next to the door was what looked like a two-way mirror, and apertures through which cameras could be focused.
"Wait!" Marcy cried, starting after him. "Don't leave me!"
Kyle got to his feet and barred her way, putting an arm around her and holding her close. "He's not leaving us, really. He'll be watching everything we do, and if he gets excited enough, he'll come back and join us. Just relax, and let us teach you the things he wants you to learn."
Karla came up on Marcy's other side, still playing with her big, puckery nipple. "Shall we give her a quick kick to get her mind off Doctor Dirk? That outfit kind of turns me on anyway. Look how those lipsticked tits show through that thin silk. Doesn't that give you ideas?"
Without waiting for her brother to answer, she leaned forward and put her mouth right on Marcy's left breast, expelling her hot breath onto it as she wet it with her circling tongue. Kyle immediately did the same thing to the right breast. The sudden lustful assault caused Marcy to gasp, and her knees almost buckled.
"She digs that," Karla said, sucking noisily on the rigid flesh that gleamed like a ruby through the wet silk. "Keep sucking, Kyle. She's as hot as a pistol already."
The girl's hand darted up under the transparent outer garment, located the zipper, and opened the crotch of the tiny panties. Slipping a finger between the cunt lips, which were still swollen from the activities of the night before, she laughed gleefully. "She's all wet and slippery, and we've hardly touched her. Shall we just keep doing this until we make her cum? It shouldn't take long. Feel for yourself."
Marcy nearly fainted from excitement as Kyle's finger joined his sister's in her sopping cunt. And when both mouths returned to sucking greedily at her nipples through the sheer cover-up, tides of lust crashed through her, and she shook like a leaf in a gale. Two arms, one male and one female, went around her to support her, and two sets of fingers fucked in and out of her juicy furrow. Meanwhile two expert mouths licked and nibbled at her throbbing breasts.
"Wow! She's almost there," Kyle giggled. "Do her clit, Sis, and she'll go off like a firecracker!"
"Yes," Karla agreed, and the pad of her thumb made instant, tingling contact with the sensitive button.
"Oh God," Marcy wailed, jerking and pulling at the arms holding her, trying to get away from, or closer to – she didn't know which – the sucking mouths and probing fingers. She screamed again and fell to the floor, thrashing around wildly. Kyle and Karla fell with her, never stopping their maddening caresses, and obviously enjoying their control over her.
"Cum!" Kyle ordered, his fingers sinking into her passionate depths.
"Cum!" Karla echoed, her touch on the clitoris delicate but sure.
Marcy was lost. All semblance of reason fled, and she shook and trembled as though having a fit, wailing and rolling as orgasm after orgasm swept through her.
"Please," she begged helplessly, knowing she was at their mercy. "Please!"
And finally they relented and let her go.
"Great!" Kyle laughed. "The Doc has got himself a hot one here."
"He sure has," Karla agreed, busy pulling the filmy white garment over Marcy's head. "Now let's get down to some good, old-fashioned screwing. Dirk Villiers can call it an experiment if he wants to, but we all know what he wants to see is some plain and fancy fucky-fuck."
"Please, just go away and leave me alone," Marcy said, trying to crawl away from the reaching hands. "I'm going to take a bath, go to bed, and sleep for the rest of the day."
Karla grinned impishly. "Did you hear that, Kyle? Marcy wants to take a bath and go to bed."
"Groovy!" Kyle said, grabbing Marcy's ankle and hauling her back toward them. "That's just what we'll let her do."
"Sure we will!" Karla giggled. "We'll throw her in the Roman bath, soap her up, and show her what fun it is to play our version of bathtub games."
"And then we'll take her to bed and act out all the dirty jokes we've ever heard about the farmer's daughter," Kyle added.
"No," Marcy said, afraid of her own reactions as much as of this outrageous pair. Their all-pervading sensuality seemed to be catching. She could feel something dark and hidden stir inside her, responding to them. "I'm going to bed by myself."
"No you're not, baby," Karla whispered, bending over to kiss the sloping white shoulders and satin-skinned neck. "We've got all kinds, of things to teach you. Doctor's orders."
"What we did to you just now was only a sample," Kyle whispered in the other ear. "We're the only brother and sister sex team who admit to it openly. There isn't anything we won't do, especially for such a sexy, long-legged cunt as you."
Karma's soft little hands fluttered over Marcy's breasts, caressing them with feather-light touches. "You want us as much as we want you, Marcy. Look how hard and swollen your pretty titties are! You can't fool me. I'm a woman too, you know."
Marcy shook her head in denial of the girl's words, even though she knew they were true. The beautiful bodies so close to her were driving her crazy. The girl's perfumed fingers were gently pinching her nipples, and the youth's thumb was agitating her clitoris, while his palm pressed against the dripping cunt lips, moving in a deliberately arousing circular motion.
"Marcy is going to swing with us," Kyle murmured. "We've got her turned on, and we're not going to let her stop until she's done everything with us."
"Yes, she's all ours," Karla purred, unhooking Marcy's bra and tossing it aside. Her hands cupping the freed spheres, her lips sought Marcy's, and her honey-tipped tongue dipped into the other girl's mouth.
Kyle fondled his sister's exposed breast, and then leaned over to suck it briefly, pulling the oversized nipple into a long coral point.
"It excites you to see me do that, doesn't it, Marcy?" he asked. "Nearly everyone gets an extra charge out of seeing Karla and me handle each other. Just knowing we're brother and sister somehow adds to the thrill. I guess you could say they enjoy our incest vicariously."
Again Marcy was amazed at the impact words could have on her. She could feel the sudden increase in wetness around the fingers Kyle was teasing her with, as a shiver of undiluted lust went through her. Incest! Wasn't that what she had been thinking about before Dirk Villiers had ruptured her maidenhead?
"You wouldn't believe some of the things we do," Kyle said, unhooking her garter belt and tossing it aside. His lips followed closely behind his hands, as he slowly rolled the black net stockings down her thighs, planting moist kisses on one leg and then the other, and leaving hot spots to sear her flesh like brands.
Karla's mouth pulled one of the lipstick-smeared nipples, sucking it hard while crushing her bared breast into Marcy's other aching mound. The erotic sensation of breast pressed to breast was incredible.
Marcy's breath was coming fast. She had never even imagined being made love to by two persons at once, and the waves of passion radiating out from her throbbing nipples broke continuously through her whole body. Her thighs ached with a hunger she could no longer make a pretense of denying.
"Beautiful sexy Marcy," Kyle was crooning as he drew the ridiculous zippered panties down and off, and then opened the lushly forested slit between her legs. "Look, Karla, look! Isn't that gorgeous? Did you ever see a pussy so lusciously eatable?"
"Never," his sister said, crouching beside him to press her mouth into the silky fuzz that covered Marcy's mound, parting the hair with her tongue and licking the inflamed cunt lips. "Delicious!"
"Oh God!" Marcy moaned, and thrust against the girl's mouth in wanton invitation.
"That's it! Open up that spicy cunt and let her taste the sweetness!" Kyle urged, planting kisses all over Marcy's belly and flanks, before lowering his head and watching his sister lap at the pink slit.
"That's enough," he said. "Don't make her cum! Keep her panting for a while. Let's get her into the tub."
"Right on!" Karla said, and got to her feet. Between them they lifted Marcy and guided her toward the bathroom.
"In here," Kyle said, pushing open a door. "Welcome to our watery paradise!"
Marcy blinked and looked around. The bathroom was anything but little. It was almost as large as the living room in an ordinary apartment. The walls were hung with copies of erotic murals, which depicted all kinds of sexual acts being indulged in by a remarkable assortment of men, women, children, and animals.
"Our inspiration," Kyle grinned, as he saw Marcy's eyes grow round, "although I must admit that generally we don't need any."
"Here's the Roman tub I told you about," Karla said, urging Marcy toward the center of the room. "How do you like it?"
To Marcy it looked more like a small swimming pool than a bathtub, and the divans and piles of cushions around its edge added to the air of luxury. The slanting sides of the bath were padded and covered with waterproof material as soft and sleek as satin, and the water was warm and scented.
Karla turned Marcy so that she was facing her, took her in her arms, and kissed her passionately. Marcy moaned as she felt the prodding of the girl's nipples against hers, and the hot insistence of Karla's sex pushing into the pulsing pink lips of her own cunt.
"Get undressed, darling, so we can begin," Kyle said to his sister, casting aside his headband, loincloth, and slave collar. Karla released Marcy, and went to stand beside her brother while she undid the clasp at her shoulder. She let the flowing gown drift down her body and settle around her feet.
The pair clasped hands and faced Marcy, proud of their naked bodies and supremely confident of her approval.
"Do you like us?" Karla asked, and Marcy could only nod. The dizziness caused by the scented warmth and the lust they aroused in her caused her to sway.
"Are you ready to fuck us?" Kyle asked.
Marcy's knees turned rubbery at the incredible eroticism of the brother and sister inviting her to share their incestuous passion.
"Will you join us now in blissful carnality?" Karla whispered, coming closer.
"No, not yet," Marcy said, surprising them and herself. "First I want to see you two together. I want to see the brother fuck his sister – no, I want to see the sister fuck her brother! You get on top, Karla. I want to see you capture Kyle's hot cock in your dripping cunt. I want to see you impaled on your brother's prick." The words poured out in a rush before she could lose her nerve.
Karla clapped her hands in delight. "Oh, what a lovely idea! We just love to put on sex shows for our friends! Lie down on that mattress right there in front of Marcy, Kyle, and let me rape you."
Kyle stretched out with his rigid cock aimed at the ceiling, and as his sister moved to mount him, he caressed her breasts and nibbled at her neck and ears. "Okay, Sis, rape away. I hope Marcy enjoys it as much as we will."
Karla was poised over her brother, letting the pink folds of her outer cunt lips barely touch his eager cock. He groaned and squeezed her breasts while she rubbed her nectared pussy back and forth over the highly sensitive cockhead, and shivered in lustful anticipation.
"They're brother and sister," Marcy was muttering to herself. "Sister and brother, and they're about to fuck each other. If they can do it, why can't Jimmy and I?"
Hardly aware of what she was doing, she got down on her hands and knees and crawled between their outstretched legs so that her face was almost touching Karla's round bottom. From there she could see the pouting pink cunt lips open under the pressure of the pulsing cock, and the musky odor of their arousal surrounded her.
Marcy watched, entranced, as the rosy folds slowly engulfed the tapering cockhead, and then the long length of thick pole. When Karla's lips met Kyle's in an openmouthed kiss, and they started the full, deep, fucking movements, Marcy's hand sought her overflowing cunt, and her fingers worked frantically in and out in a matching rhythm.