Incest Sex Stories

Unintentional Incest

by Anonymous

Disclaimer: This sex story contains incest between brother and sister

"Fucking morons!" Kirsten thought.

At the door to the chemistry room, two of her classmates Bill Taylor and Scott Vance, or Jackass #1 and Jackass #2 as she thought of them, were waiting as usual. The pair of morons partially blocked the class's doorway forcing all the girls entering to pass between them, giving the boys the opportunity to goose them or fondle them in some manner.

As Kirsten tried to enter Scott bumped into her side shoving her towards Bill who, on the pretext of helping her, reached out his hand and squeezed her breast. Anticipating this crude assault, Kirsten elbowed him in the stomach and for good measure kicked Jackass #2 in the ankle.

"Hands off pervert. Try that again and you'll be singing Soprano for the rest of your worthless life."

Her quick response got a laugh from all those who witnessed it, especially the girls who got the same treatment before.

Chemistry was the last period and Kirsten was too tired and bored. While she enjoyed chemistry usually, today her mind was preoccupied and she was unusually horny. Alas, she had no boyfriend currently to help her relieve the incessant itch that was bothering her today. At seventeen, she had yet to find the perfect guy that she felt she needed.

In hope of cooling down her horniness, Kirsten decided to do some weight training at home right after school. So as soon as the final bell rang, she threw on her coat and ran out to her car and drove quickly home.

At her seemingly empty home, Kirsten dumped her schoolbooks and coat on her bed and stripped off her clothes, panties, and bra. Her breasts luxuriated in the release from their tight confinement. Her bra is getting to tight again. She got new bras barely a couple of months ago and it seems she's already outgrowing the 34C that she replaced them with. Her breasts settled hardly at all. Her twin mammary peaks rode high on her chest, a beautiful testament to her youthful tight skin.

It must have been her horniness affecting her sub-conscience, but this day, for working out, she chose to wear a pair of old, too small jean cutoffs that barely made it over her hips and whose crotch was so narrow that it rode up high between her ass cheeks and parted the lips of her pantiless pussy. A loose short tank top that barely covered her tits completed her outfit. She headed for the basement to her dad's workout room.

As she came to the weight room door she heard sounds inside. She padded quietly to the door and peeked into the room. Her fifteen year-old brother Kevin seemingly had the same idea of an after school workout and he had gotten here first.

Though two years younger, Kevin was already two inches taller than Kirsten. His tousled sandy hair, deep blue eyes, cute face, and the dedicated work with the weights made him a fine figure of a lad. Actually he had quite a hunky body, even if he was only fifteen.

Kirsten admired her brother's muscular body and was especially fascinated by what seems to be hidden under his shorts. She had not seen many cocks, but Kevin's seems to compare well in size with all of them. It looked to be much larger than Pete Hanson's.

Pete had been her date for last springs' Junior Prom. He was an okay guy; and last year before her body had filled out, he was the only one to show any interest and asked her to the dance.

After the Prom dinner and dance, Kirsten and Pete had been invited to an After Party at his friend Jane's; but like many of the couples they had made a stop at Davis Park first. Davis Park was a series of lanes and fields back near Davis's Farm. It was the favourite parking spot for the area's kids.

Pete found a secluded spot under a tree. He pulled in and turned the car off. Kirsten had done a bit of necking and groping before, but tonight she intended it to be more than that. When Pete slid across the seat and put his arms around her and craned his neck forward for a kiss she met him with her lips parted and welcomed his tongue between her moist lips.

Her excitement ticked up a couple of notches as he pressed their heated kiss and moved his hands up to caress her shoulders. Heat spread through her arms and torso as Pete's hands slid down over her smooth shoulders. His mouth left hers and he slowly trailed kisses across her cheek and lightly nibbled on her ear and neck as his hands moved to the top of her gown zipper and started to tug it down.

Kirsten hugged him tighter as she leaned slightly forward allowing him to pull the zipper completely down. She sat back and Pete pulled her dress top down leaving her naked from the waist up. Back then her breasts were only smallish swellings, but her ultra sensitive nipples even then were engorged like large erasers, advertising her extreme arousal. Pete dove forward and captured a nipple between his lips, gently tonguing and teasing the swollen nub out even further, as one hand came up to fondle and pinch the other boob.

This double assault caused fire to sweep from Kirsten's breasts throughout her body and quickly kindle a bonfire between her thighs. She felt her vaginal lips start to swell and her as yet virginal love tube begin lubricating. Her own hands were stroking up and down his back as the assault on her tender tits kept on. Pete lifted his lips back up to hers and their mouths locked as both his hands squeezed and molded her pliant breasts. All thought was gone from Kirsten, just raw sensation and lust controlled her hands as she pulled the jacket from Pete, unbuttoned his shirt, and started to work on the zipper of his pants.

She moaned softly when his hand left her right breast, but she felt it quickly settle on her knee and start to push her skirt up. Her hands were urgently kneading the bulge she found under his zipper and she worked the opening wider to get into his shorts.

Pete soon had her skirt bunched up high enough to get to her bare knee and slid his hand up the inside of her leg pushing the dress with his arm. Kirsten let her thighs spread apart to allow access to her already wet crotch. Both fumbling fledglings jerked when Pete's hand reached the junction of Kirsten's soaked thighs. He, in surprise at finding no obstacle to is probing fingers, because before leaving the prom Kirsten had slipped into the Ladies Room and removed both pantyhose and panties, hoping that things would progress this far; and she, as a male finger abruptly slid in where only her own fingers had been before. Both jerked a second time as Kirsten's hand found it's way into Pete's shorts and her fingers wrapped around his stiff penis.

Both teens were too inexperienced, not to mention too excited to indulge in much in the way of foreplay. There was a brief hilarious (for anyone watching) Chinese fire drill as the semi-clad pair scrambled out of the front seat and into the back; then more pulling and grunting as bodies were arranged and clothing disarranged. Finally Kirsten got herself mostly reclining on the seat with her gown pulled up around her waist and Pete lying between her splayed out legs.

There was even more maneuvering and huffing as the two virgins tried to get the appropriate body parts aligned. Finally Pete managed to get the head of his cock seated between Kirsten's puffy vaginal lips. Then more by accident than planning pushed at just the right time and jammed the head of his swollen staff up into Kirsten's receptive woman sheath. Both froze for an instant. Kirsten tried to shift her legs a little to better accommodate the thick intruder into her body, but Pete didn't notice or seem to care. He jerked his hips down and forward trying to force all of his cock into her.

There was only a brief flair of pain as his intruding piston pushed deeper and deeper into her passion swollen tissues. The breath whooshed from her lungs as a final jab brought Pete's hips firmly up against Kirsten's cuntal mound. She had no time to sort out separate feelings or sensations before Pete jerked his hips back, drawing his now cunt juice coated prick nearly out of the newly fucked girl's honey pot, then slammed forward again until their crotches slapped together. All sensation was centered in Kirsten's clasping cunt. The quick stabs of the frenzied boy's penis into her still sore woman canal sent shocks of lustful electricity throughout her body.

Kirsten lifted her legs up around Pete's waist trying to get more pressure on her clit, as he started a rapid pumping of his blood fattened sausage into her dripping female hole. He hammered into her only a few times before a final lunge and shudder signaled he had shot his load of cum juice into her. He cuddled her for a few minutes and sucked on her tits, then started to get dressed mumbling about getting to the party. Kirsten had not come and felt vaguely unfulfilled and very disappointed that that was all there was. But she said nothing.

They had only gone out a couple more times before school was over for the year and had screwed only once more. Kirsten had taken to rubbing her clit and sticking a finger into her ever-horny pussy each evening. Then one Tuesday after supper her Mom called up to her room that Pete was at the door. Kirsten pulled on a tee shirt and a pair of shorts and ran down to greet him.

"Hi Kirsten", mumbled Pete. "I was wondering if you would like to go for a walk, or something."

"Yeah, sure," smiled the pretty teen.

The two of them wandered hand and hand in the general direction of the school and the park behind it. By unspoken agreement they strolled to the edge of a small copse of trees and stood there making desultory small talk. Pete finally put his arms around Kirsten's shoulders, pulled her to him and kissed her. His hands stroked down her back and gripped her tight butt cheeks as his tongue probed urgently into her mouth. Kirsten kissed back, her own tongue battling with his. Her arms went around him and hugged his body tightly to hers. She ground her hips against his and felt his penis rapidly hardening.

Pete broke the kiss long enough to fumble at the buttons and zippers of his jeans and Kirsten's shorts. He pushed his pants down, then hers, and returned to the fierce, sloppy kiss as he mashed his sex weapon against the hot girl's bare stomach. Pete was a few inches taller than her so Kirsten finally broke the kiss and turning around, dropped to her hands and knees. She looked back over her shoulder and said, "Come on Pete. We can do it this way, no one will see."

The excited boy gazed a long moment at the hot ass of this beautiful female, then dropped to his knees behind her and awkwardly shuffled between her legs. After a bit of fumbling he succeeded in shoving his cock up her. It was over quickly, just like in the car after the prom, but at least this time Kirsten managed a weak orgasm. She had not seen Pete, except occasionally at school, again.

These thoughts quickly flashed through Kirsten's mind as she watched her brother doing arm curls. Yes, his cock definitely looked bigger than Pete's. But this was her brother she was ogling— so she dragged her thoughts back to her workout and bounced into the room.

"How's the bicep building biz, bro?" she quipped as she headed for the barbell stand.

"Have to keep in shape to beat off all the women, Muff. You're looking pretty good, how was practice?" returned her sweating sibling.

Kirsten put 103# on the bar ends and lay down on the bench to start her presses. When she reached up to grasp the bar the short top pulled up almost uncovering her nipples. The whole under slope of her breasts was exposed to view. She grasped the bar and grunted with strain as she started her press.

"Hey dummy, you know better than that!" admonished her brother.

He laid down his hand weights and came to stand behind her head so he could help with the weights in case she tired too quickly.

"The guys at school would never forgive me if I let you harm that magnificent chest of yours. They enjoy watching your tits bounce too much," Kevin grinned as he watched his sister's straining bust.

"Names! I want names, darling brother," kidded Kirsten as she set the bar back in place. "I've heard a couple things said about your bod as well— in the girl's locker room."

They traded places and as Kevin got himself comfortable Kirsten added more weights to the bar. At his 9th rep Kevin was obviously straining.

"Ah— Muff, watch close. I think I can get one more but may need a bit of help."

He had the bar almost back to the stand rungs when his arms started to tremble and shake. Kirsten tried to help from where she was at behind his head, but couldn't get the right leverage. So she quickly jumped around to straddle his chest and lift that way. Phil's arms gave out; but between them they managed to angle the falling bar so it did not hit either of them. Kirsten's momentum caused her to fall across her brother and the exertion pulled her top up to her armpits, exposing her chest and the fully engorged nipples. One of those nipples ended up pressed against her brother's lips.

As they lay still a moment, catching their breath, both gradually realized what parts of their anatomies were situated where. Kevin's lips slowly parted and his tongue gently flicked at the nipple. This sent a thrill throughout Kirsten's body. When his sister didn't move, Kevin started to slowly suck on the still hardening breast tip and his hands came up— one to rest lightly on Kirsten's half bare butt cheek and the other to grope for her other tit.

The suction only intensified the sensations firing throughout Kirsten's body. She shifted her body to shove more mammary meat into her brother's mouth and allow his hand access to her other breast.

There was only the sound of heavy breathing in the room. Kevin sucked harder and harder on the full-bodied woman flesh in his mouth as he pinched and pulled on the other nipple. His other hand found it's way under the narrow strip covering Kirsten's crotch and worked it's way down to tease at the bottom of her steadily lubricating crack.

Kirsten spread her legs wider over her brother's hard chest allowing his finger to slide up through her vaginal lips and sink into her by now dripping hole. The intimate contact jolted them both out of their lustful haze. Kirsten jerked her upper body back, popping her red and straining boob from Kevin's mouth. She gazed deeply into her brother's eyes and trying to keep the mood light, quipped, "Hey bro, that finger is getting kind of personal, don't you think?"

"I know, Muff. We shouldn't be doing this," Kevin said slowly. "But it feels so good to hold you," he continued adding a second finger to the first inside his sister's hole and easing them both deeper into her body. A low moan escaped Kirsten's throat as her hips hunched down, the muscles of her love tunnel working to draw the welcome intruders deeper inside.

Kirsten, again almost lost in a lust-induced trance, leaned down to kiss the loving face of her little brother. Their tongues invaded each other's mouths and Phil's hand went back to the breast it had been fondling. As the intensity of their kisses grew Kevin tried to slide a third finger into Kirsten's slippery pussy folds. The discomfort of the stretching caused her to reach a hand down to pull his fingers out. But in the fumbling, Kirsten's fingers found something more interesting. The thrashing about when the barbell fell and the bodily squirming since had pulled Kevin's jockstrap awry. Kirsten's questing fingers found his hard cock. His loins jumped when she wrapped her hand around the solid length of his rod. She pulled and stroked on it, reveling in the feel of the satiny skin and bulbous head.

"Please, Muff, be careful or you'll make me shoot," pleaded Kevin. "It feels so good. Do you like this?" he asked as he slid his fingers in and out of her clasping cunt.

"You should know I do," smiled Kirsten as she pumped her hips slowly onto his fingers.

They stayed this way for a minute or so, slowly and lovingly masturbating each other. Then Kirsten carefully stood up pulling her clinging vagina off her brother's fingers. As Kevin was about to protest, she slipped her shorts down over her hips and lifting each leg took them completely off. As she skinned her tank top up over her head, Kevin quickly pulled his jockstrap down his legs and off.

"OK brother dear, let's do this right," Kirsten said as she positioned her still dripping slit over Kevin's rock hard man length. She slowly bent her knees to bring her gaping nether lips to just touch the red top of his straining penis. Kirsten bit the tip of her tongue in concentration as she gently worked the head of his large sex tool into the entrance of her love canal.

The blunt tip of Kevin's sex weapon parted the dripping lips of his sister's cunt. Their mutual masturbation had already engorged her female flesh and had her juices flowing at full flood.

"Muff, please-" Kevin almost whimpered in his desire to feel more of her hot clasping cunt. Kirsten lowered herself a bit more and felt the broad part of his cock head wedge tightly at the entrance to her vagina. She slowly increased the pressure until the fat pussy plunger popped past her love canal lips and into the waiting woman flesh beyond.

"Uh, —um—oh yes," groaned Kirsten as her brother's thick penis started a slow slide deeper into her body. She planted her hands on his shoulders and held herself in place as she let the incredible sensations wash over her body and her clinging womanhood adjust to the fat man-rod forcing itself inside.

The wild sensations were overloading Kevin's nervous system. This was his first time with a girl and the magnificence of his sister's body and the feel of her tits in his hands, plus the over-powering liquid fire of her pussy slowly engulfing his cock, sent him over the edge.

"Muff, Muff, - I'm coming, "he cried as he hunched his hips upward trying to cram more of his flesh into her.

Though only the head of his cunt club was inside her, Kirsten felt the jets of baby stuff hose the walls of her woman chamber sending her into waves of overpowering orgasm also. Her cunt clamped hard on the delightful intruder that was causing so much pleasure to her body. But her brother's cock had not been very far inside her so her muscle spasms just pushed it out, —still spurting gobs of come, that splashed up her stomach.

As the climax waves slowly let up on both of them, Kevin looked into his sister's eyes and sheepishly said, "Sorry. Sis, guess I'm not so hot at this, or maybe too hot!"

Kirsten smiled lovingly at her brother and wrapped the fingers of one hand around the slimy still hard length of his manhood and softly said, "That's okay Phil, there will be plenty of time to try again."

Kevin's face lit up. "You mean we can do this again? How 'bout right now?"

Kirsten laughed and slowly stroked her hand up and down his cock.

"Don't think I'm going to let this fine piece of meat lay around idle. But right now we had better get this place picked up before Mom and Dad get home."

Later that evening as the two of them sat in the Rec Room watching TV, while their parents were watching in the family room, Kevin couldn't keep his hands off his sister. Kirsten lay on her side on the couch and Kevin was seated on the floor by her legs. He was wearing his usual at home attire of loose gym trunks and a tee shirt. She had on a knee length nightshirt, but had left her panties off.

Kevin had been rubbing and massaging her legs and was gradually moving higher and higher, pushing her nightshirt up her thighs. Kirsten enjoyed the strong rubbing and caresses and was gradually allowing her legs to drift further and further apart giving Kevin more room to massage. Her thighs spread further apart as Kevin's massaging hand worked higher and higher up her legs. His fingers kneaded her muscles deep between her legs then slid out and onto her lower stomach. Just his fingertips lightly caressed her mons, before carefully tracing their way through her curly, silky pubic hair to find the top of her moistening crack.

The television was forgotten as Kirsten pulled the bottom of her nightshirt up over her flat stomach to more easily watch her brother's fingers playing with her most private parts. Kevin's eyes were glued to the Y of his sister's legs. He couldn't believe that she was letting him play with her pussy. He slowly parted the lips of her femaleness hunting for the way to get his finger up inside her.

Even though the erotic intimacy, not to mention the forbidden nature, was causing Kirsten's tight little cunt to get very juicy and wet; Kevin's probing fingers were a bit impatient in their quest.

"Easy, little bro, - not so hard. Here, move your finger down a little, — there — gently, —ug, —oh yeah, now push in and up a little—slowly— there." Kirsten sighed as his finger slid up and into her welcoming hole. Kevin goggled at the sight and feel of his finger thrusting into his sister's cunt. Her legs splayed further apart as he worked his hand in and out of her clinging cunt. The lips of her pussy swelled and opened more and more until he could see at the top of her slit a little button of flesh swelling up.

"Muff, may I stick another finger in?" asked Kevin.

"OK, but slowly, it's tight, —and here— put your other finger up here and rub this very softly," breathed Kirsten as she took his little finger and moved it to rub on her clit.

Kevin now had two fingers plugged into his sister's soggy female hole and another trying to play with her clitoris. His other hand was busy inside his loose shorts rapidly stroking his hard cock. His manual manipulations were definitely getting to Kirsten. Her breathing was getting faster. She pulled her nightshirt up still further so she could squeeze her breasts. The juice from her sloppy slot ran down the crack of her ass and over Kevin's hand. As he worked his fingers in and out of her, his thumb was pushed between her butt cheeks and the pussy slime made everything down there very slippery.

After a couple minutes of increasingly heavy breathing on both parts, the steady pressure of his hand pressing up and in brought Kevin's thumb into direct contact with Kirsten's puckered butt hole. She jumped slightly when he initially started pressing on it and said, "Don't, not there—unh, unh, oh rub harder up there," as she redirected his fingers to pull and tug on her clit more.

But Kevin liked the idea of invading his sexy sister's ass, — so after another minute of pumping his fingers into her tight cunthole he slowly repositioned his thumb, then shoved quickly— forcing the end of his thumb through the tight muscles of her anal opening and into the clasping channel beyond.

"Oh shit, —stop it Kevin," screeched Kirsten trying to twist away from the rude intrusion. But she was at a real disadvantage because her body wasn't cooperating completely. It wanted to keep those pleasuring fingers in her warm pussy. In fact, her twisting about actually forced her brother's thumb deeper into her rear passage.

"Ow, — stop it," Kirsten cried as she brought her hands down to try and pull Kevin's still plunging fingers out of her stretched openings. Their wild thrashings pushed Kirsten's pelvis even harder onto her brother's hand and his palm rubbed roughly over her mons with all his fingers buried deeply in her cunt, up her ass, and massaging her clit. His thumb was still very uncomfortable in her butt, but all this stimulation was overriding this with waves of passion.

Kirsten rolled off the couch landing on her butt-reaming brother, but he managed to keep his grip between her legs. Just then they heard footfalls in the hallway, then their father's voice called from the doorway, "All right, what are you two up to now?"

Luckily the couch screened them from the doorway and Kirsten was able to drag her nightshirt down over her heaving tits before the two of them sat up and grinned sheepishly.

"Ah, Kevin was tickling me again, Dad. And I guess we got a bit carried away."

"Yeah, Dad," Kevin added. "Sorry about the thudding about."

"Your mother and I are heading for bed; so please keep things to a 5 on the Richter scale." Their father smiled as he turned and left the room.

As soon as they were certain he was gone Kirsten pulled her top up and looked down at her brother's fingers still plugged into her holes.

"I'm sorry if I hurt you much, Muff. I'm not sure what made me want to ream out your poop chute. Does it hurt much? I'll pull out." Kevin asked with a very tender look on his face.

"Not just yet," smiled Kirsten. "It was just the suddenness. It doesn't feel too bad now."

She gently rocked her loins back and forth getting used to the feel of having both her pussy and ass filled at the same time. Reaching into her brother's shorts she pulled out his still hard rod and started to stroke her hand up and down its length. Than leaning forward, kissed her sibling full on the mouth and pushed her tongue between his teeth.

At the state they were both in, only a minute of this torrid kissing and mutual masturbation was enough to set them both off. Kirsten was moaning into Kevin's mouth and bouncing harder on his fucking fingers when he shot squirt after squirt of semen onto his sister's belly and thighs. While his fingering caused her clinging cunt and ass to spasm in orgasm.

After a couple minutes of tender cuddling and hugging they lovingly helped each other clean up and then tiptoed up to their beds.