"Hey mom, some of the others were talking about spending the evening on the beach around a campfire. Is it okay if I stay up a little later than usual?" the young rodent asked as he finished his meal, almost startling his mother whose mind was elsewhere.
                "Oh. Uhm sure sweetie, just be back before midnight and don't cause a racket." She replied, figuring it was better than having him in the house while she was having her issues.
                It had been a while since they'd managed to have one of these little family getaways, and they'd all been so excited, especially Kenneth. There was a three day weekend coming up and Diane's husband had managed to get a day off Thursday, meaning they'd have four days to spend at the little lake-side bungalow they'd booked.
                The first wrench in the gear works came when one of David's coworkers got in a car accident, one that was just serious enough to keep him away from the office for weeks. That meant that somebody else had to pick up the extra work, and her hubby would be lucky if he managed to join them for Sunday. Diane had suggested they put it off for some other time, hating the thought of her mate working long hours and then having to come back to an empty house, but he insisted that they go since Ken had been looking forward to this for over a month.
                With an eager thanks, her son dutifully cleared his plate and dashed out the door. When he got up, Diane couldn't help but catch the sight of his swim trunks. She made sure to buy him very baggy pants, but despite that they were looking a little snug in front, something she knew was her fault, as well as her son's... endowments.
                Looking at Ken one wouldn't assume for a second he was anything other than a rat, same as his parents, but once he was born Diane and David learned they both had a little canine somewhere in their family tree, and that meant Ken also had a bit of a canine trait. One that required a sensible mother to buy him pants that were as loose as possible around the crotch.
                The sight of him had gotten her a little short of breath, because of the second little calamity that had befallen their vacation. With the packing, unpacking and making sure her hubby at least had a fully stocked fridge and a few meals he could heat up, Diane had managed to forget her pills. She could imagine the little box, probably still on her nightstand (in plain sight, so she wouldn't forget!) and just over a hundred miles out of reach. 
                She'd been taking them since she had Kenneth back when she was twenty, and after fourteen years without one, her heat had come back with a vengeance. She tried to keep her son in the dark about it, since it was so irresponsible that it was embarrassing. To make matters worse, an all-species blocker was still only a pipedream, which meant that there were separate meds for females of every shape, size and form. Every pharmacy was required by law to keep a little bit of every variety in stock, and these days most mega-marts covered pretty much every species since it was over-the-counter medication.
                But they were now in a lovely, remote little vacation town, the place that was meant to supply various necessities to the tourists renting the cozy bungalows dotting the lake's shore. It had one supermarket, and while they carried contraceptives they didn't carry heat blockers. And that was the perfect storm for Diane - if her husband hadn't been called away, they would just have bought an economy pack of condoms (or two) and their only concern would have been keeping quiet enough not to wake Ken up.
                Once her son was out the door she breathed out a sigh of relief. It was their first day, and she was wondering how much longer she'd be able to keep coming up with excuses for staying indoors. The thought of going to the beach in her condition was out of the question! Diane was proud of the way her body had bounced back after her pregnancy, knowing that she was almost thirty-five and had the build a twenty year old might envy. Having a child had filled out a svelte rodent frame in just the right places, particularly the DD cup breasts gracing her chest, still firm and bouncy even after all these years.
And that was part of the problem. She knew David loved the way she looked, and since this was a little getaway, she'd intended to give her hubby something to look at. The swimwear she'd packed left very little to the imagination, which would have been fine if she'd been out of heat with her man by her side, obviously a spoken-for woman looking to entice her mate a little.
But it would be an altogether different story if she went out in a skimpy bikini reeking of estrus. Even her wedding ring wouldn't help there, with people assuming she was some sort of slut so eager to have an affair that she went off her blockers on purpose. While the meds were species-specific, the pheromones she was giving off weren't and she couldn't go out and have Ken watch as a steady stream of horny males came over to hit on his mother. Or worse - to introduce him to his new friends and have the teens suddenly sport tents and drool over her.
She wondered briefly if she could drive back home, or try to find a pharmacy, but it was no use. She wasn't keeping track of her cycles and this morning she'd missed a critical pill. Even if she took one now, it would only kick in once her heat had run its course. And it would get worse tomorrow! Her only hope was to bluff her way through this. She'll try and tell Ken she wasn't feeling well in order to excuse herself from going out, but that left other problems.
She was hesitant to air their little bungalow out to much, since there were species out there that could track the scent of her heat to it, and she didn't want some horn-dog showing up at her door suggestively asking if he could borrow a cup of 'sugar'. But that meant Ken was in a house reeking of a female rodent just coming into heat. She was sure her boy wouldn't be able to tell what it was, but smell had a strange way of triggering instinct. There were several pretty young girls among his new friends, and Diane was worried that her pheromones could cloud Ken's mind enough for him to... to do something her baby was still too young for!
Sighing in both feminine and maternal frustration, she made her way upstairs, to what should have been her and David's room. The upstairs was just a bedroom with a comfy bed big enough for two, with Ken having a folding couch and the living room/kitchen all to himself. If she'd forgotten her blockers but had David along, the only problem would be that the rat would have gone back to work looking more tired than when he left for his relaxing vacation.
Still, the rat femme had managed to find something at the grocery store that might help a bit. She popped out one of the pills - a non-prescription sleep aid - and almost swallowed it before remembering just how hard getting to sleep would be. Instead she wound up taking two before getting ready for an early, and what she hoped was a peaceful night.
She sighed in relief when she got down to her underwear, since being in estrus always made her feel like she was hot and stifled. And it being early summer, she figured she'd just sleep naked tonight, with the sheet being enough to preserve her modesty should Ken walk in. The last thing he needed to see was his mother buck naked in a room smelling to high Heaven of feminine need!
As she peeled her panties off the rat femme blushed when she saw the neatly folded tissue she'd pressed against her lips was already soaked through. Diane had even sprinkled a few drops of her perfume on it, hoping it would mask her scent, but her body had seemed determined to drown it out with her own personal fragrance.
With the last remnants of her clothing gone, she settled into bed and got ready for what she hoped wouldn't be a restless night. One of her hands drifted lower, her belly twitching as her fingers slid along it as they reached further and further down. Diane knew how futile this was, that all her touch would manage to do was get her frustrated, but she couldn't help herself. She was still squeaking quietly, her fingers dipping in and out of her sex vigorously at first, but slowing down as the pills granted the rodent femme some respite from her burning urges.
*******
True to his word, Ken got back a little before midnight. He'd had a blast with his new friends and was ready to hit the sack until he stepped inside and seemed to get a second wind. He'd unfolded the couch and made his bed when he got the idea to go and check on his mom. She'd been acting funny since they got here and didn't even walk up to the beach, and the young rat knew he'd sleep sounder if he knew she was fine.
The narrow staircase took him to the upstairs room and Ken figured he'd just peek in without knocking, not wanting to wake his mother up. The door opened silently and as wide as the rat's eyes as they fell on his mother's body lying supine on the large bed. She seemed to have dozed off without switching off the bedside lamp, and while Ken had inherited his dad's light-brown coat his mother's fur was a pristine white that seemed to shine in the soft glow. Especially since so much of it was on display!
She was lying on her back but Ken guessed she must have been tossing and turning a lot since her hair was spread out all over the pillows and the sheet that had been covering her was tangled between her legs. And it was the only thing that had been covering her! The burning in the teens lungs reminded him that he hadn't taken a breath since it had been knocked out of him by the sight of the sleeping beauty, and he found himself trying to pant as quietly as possible.
His first coherent thought had been to close the door and give his mother some privacy, but he never got around to it as his head seemed to swim with every lungful of air he took in. He thought he might be hyperventilating so he closed his mouth and began to breathe through his nose. Even though he didn't know it, that had sealed his fate. Diane had forgotten to leave a window open, and the air in the cozy little loft was thoroughly laced with the scent of her heat, especially after her little fingering session.
Ken had sat through sex ed classes in school, but he'd never caught scent of a fertile female. Knowing what pheromones are and how they affect the brain wasn't a lot of help when you were taking breath after breath of the mind-fogging scent without realizing it. The young rodent didn't even notice his canine shaft swiftly swelling and leaving his sheath, his feet carrying him as if on their own closer to the sleeping female.
Kenneth had never seen his mother like this - buck naked and seemingly frozen mid-writhe, her muzzle parted slightly and her breasts rising and falling gently with her every breath. It was because of that that he wasn't really seeing his mother, but rather a gorgeous woman still in her sexual prime, her alabaster curves seeming to glow gold from the light of the nearby lamp. A part of him told him this wasn't right, that he shouldn't be thinking of her like that and that he needed to get out of the room and go to sleep, but it was getting harder and harder to listen to that voice.
Before he knew it Ken was at the side of his mother's bed, staring at that chest rise and fall to the rhythm of the sleeping female's breathing. Her naked breasts looked nothing short of perfect - two snowy mounds with little patches of pink in the center, her perky little nipples close enough to...
It seemed to the teen like he was watching someone else, his heart pounding in his ears as his hands moved closer and closer, each one headed for one of his mother's tantalizing mounds. He held his breath as he held his palms an inch or so over them, close enough to feel the heat of her body until he finally mustered the courage to lay them against the pale teats. He let out a long shuddering breath of both relief and arousal as his mother didn't seven stir at the touch, her perfect globes feeling magnificently soft and warm against his palms.
His cock throbbed in his swimming trunks as he gently squeezed the alabaster globes, his nose twitching as the scent of the fertile female stroked his already hormonal brain even further. The voice telling him this was wrong was gone now, and the teen only wondered how far this could go. He continued to lovingly grope the rat femme's breasts, occasionally running the pad of his thumb over her pink nipples and watching as the nubs stiffened and poked out. His mother gave no sign of waking, her expression unchanged since he'd came in here - eyes closed and her slender muzzle slightly open, soft lips parted just a little...
Even though he didn't know it, Ken was now almost drunk on his mother's pheromones, his nostrils widening as he kept in taking in more and more of her scent without even realizing it. And with every second his inhibitions were lowered even as his need grew, to the point he found himself taking his shorts off and freeing his member.
His mother had always insisted there was nothing wrong with him down there, and that his boy-parts were just a little special because he had canines somewhere in his ancestry. His member was all the way out of its sheath, and the teen knew that counting the still slim knot it was almost a foot in length, something that should have been swinging between the legs of an almost seven foot tall Great Dane rather than a teen rat that had so far barely cleared five feet.
He always wore baggy clothes and didn't have an attitude to go along with his endowment, so he usually wound up with somewhat shy and inexperienced girls who got intimidated once they realized what he had. That was why despite having several girlfriends Ken never got further than some mutual touching, since girls seemed to be nervous about even taking what he had into their mouths.
It was that thought that unglued his eyes from the pliant globes of feminine flesh under his palms, to his mother's long, slender muzzle, and those just barely parted lips. He took his hands off the buxom rat's chest, noting that they were trembling with excitement as he used one to gently prop up his mother's muzzle while the other guided the tip of his red shaft towards her mouth.
Ken had to bite his lip to stifle a groan at the sensation of velvety lips kissing his tip, his cock immediately twitching and sending a strong squirt of pre into the sleeping rodent's maw. He pushed in a fraction of an inch before he felt Diane's incisors blocking his path, wondering at how great it would feel to slide his cock further in, to feel her velvety tongue pressed under his shaft.
"M-mom? You awake?" he asked softly, the words still seeming loud in the utter silence of the room, but despite the fact that his mother's big round ears should have caught the question, the woman remained sound asleep. That encouraged Ken and he pressed one finger against his mother's nostrils. With her nose blocked, the sleeping female instinctively opened her muzzle just wide enough for the teen's cock to slip in. Ken unblocked her nose as he moaned softly, slowly sinking inch after throbbing inch of his shaft into the rat femme's warm, wet and apparently welcoming muzzle.
His tail twitched as he did his best to muffle a groan, the sensation of his slumbering mother's mouth around him feeling more amazing than anything he'd imagined. A voice in the back of his head cried that this was wrong even if she didn't catch him, but Ken just eased his conscience by telling himself he'd just do this for a few seconds longer than go downstairs and finish himself off. That was before those parted lips wrapped themselves around him and the sleeping woman began to very gently suckle the length she was being fed.
The nature of Diane's heat-dream was predictable, but the rat femme was surprised when the sensuous haze seemed to crystalize, becoming more lucid but no less lewd. In her dream she opened her eyes to see her husband by her bed, naked and quite obviously glad to see her. They didn't exchange any words and she guessed he must have gotten out of work and driven here to surprise her. She felt a thrill at the thought that her knight in shining armor was here, that her heat was a dragon that had taken her captive and her hubby was about to defeat it with that spear that was even now bobbing in front of her face.
She opened her mouth to the point she felt her jaw straining slightly, guessing her mind had upgraded her hubby a little since she never had to work all that hard to get his shaft into her muzzle. But despite the slight exaggeration, the whole thing was amazingly vivid, down to the sensation of a throbbing cock pressing her tongue down, the taste of the juices it was leaking into her mouth and the smell of an aroused male cutting through the miasma of her pheromones.
In the waking world, Ken couldn't believe what he was seeing. His mother's full lips were wrapped around his canine shaft, forming a seal as the sleeping female suckled lovingly on the throbbing length. He knew just how big of a mess his equipment could make and it seemed to be outdoing itself now that there was something other than a hand wrapped around it. His eyes went to his mother's throat next, his mouth hanging slack at the sight of the gorgeous woman gulping down every squirt he shot into her mouth.
Any thoughts of just pulling out and leaving her in there went out the window when his sleeping mother moaned softly into his cock, the vibrations of her lusty vocalization threatening to push him over the edge already. His plans changed then and there - he was going to finish inside his mother's muzzle, clean her up as best he could, and then he'd definitely leave.
Putting one hand gently on the back of her head, Ken very carefully pushed the rest of his shaft into Diane's mouth, feeling the tip slide into her throat before the swollen bulge at the base of his cock pumped her nose. He was worried his mother might start choking, but she kept moaning all the while, the tip of her tongue stickling out and just barely reaching the teen's massive sack. The two heavy orbs were almost as big as tennis balls after Ken spent the whole day seeing both girls and women in their bathing suits, and were eager to empty themselves down that slender throat.
He carefully began to pull out, still afraid that his mother might stir, but the woman remained completely out of it, dreamily sucking and moaning around the cock that was now slowly sliding in and out of her muzzle, pushing part way down her gullet every time Ken sheathed himself. Ken buried one hand into his mother's hair, pulling her head back and forth just a little in time to his thrusts as the other remained fisted at his side. 
He was struggling to hold back, wanting to prolong this moment as much as he could since he had no idea when he'd be able to find a girl willing or able to do something like this for him. His toes were curling and his swollen sack was drawing up against his body, sure signals that the young rat was about to feed his sleeping mother his incestuous load. When the mounting pleasure got too much to bear the teen groaned out, pushing his mother's head against his crotch and ensuring the tip of his shaft was lodged in her throat before he finally let loose.
In her dream, Diane's role was a lot more active. Her husband's hand was on her head but she was the one greedily bobbing up and down on his shaft, suckling on it like a babe at her mother's breast. She could almost hear his muffled moans, something they'd both gotten into the habit of doing so that Ken wouldn't overhear them. She could almost see herself whorishily attacking the throbbing member until her man pulled her head down and kept it there, the first rich, warm jet of his seed shooting right down her throat.
Ken's hand flew to the nightstand to steady himself as pulse after thick pulse traveled along his twitching length and into the muzzle of the woman who'd borne him. He could see she was swallowing, but he was still worried she might choke with his shaft blocking her throat, so with some lingering regret he pulled out. His cock continued to spray thick globules of his cum along his mother's tongue, and once the tip was out of her mouth all over her lips and muzzle. The glistening cream shone against the matte white of the rat femme's fur as the orgasming teen drenched the slumbering woman's face in his seed.
As he came down from his high he noticed something under his palm. It was a blister pack of pills with two missing, and even though the teen didn't recognize the name of the medication, the fact that his mother hadn't even stirred while he mated with her face made him guess what it was. As he caught his breath he finally realized there was something about this room that smelled amazing. Acting on some basic rodential curiosity he lowered his muzzle and sniffed his mother's neck. 
It was mostly the smell of her fur and the shampoos she used, with a lingering hint of perfume but there was also something else. He swung his nose lower, sniffing at his mother's breasts, and it was a little more intense now but still not it. When he sniffed her belly he finally realized where the scent was coming from, but it was too late at this point.
Everything he'd learned in sex ed about preventive measures, fertility cycles and pheromones went out the window when his brain got hit with the full force of a female in heat. It no longer mattered that this was his mother, that she was clearly out of it and that what he was thinking about doing was profoundly wrong. He was between her legs before he knew it, spreading the shapely alabaster limbs and leaving nothing but the tangled sheet covering what lay between them. The scent had kept his shaft from retreating back into its sheath, and the foot-long canine length twitched at the flash of glistening pink in that white sea as Ken pulled the sheet away.
Spreading those thighs a little farther apart, Ken had his muzzle between his mother's folds before he even realized it, the taste of the fertile female's rich honey overpowering any last vestige of restraint he had. Enthusiasm made up for a lack of experience as he pushed his tongue in as deep as it would go, feeling the velvety walls twitch to life despite the fact that the woman they belonged to remained soundly asleep. A few rapid, messy licks were enough to coax a whimpering moan from the slumbering rodent's throat, and that in turn spurred on the horny teen.
He moved into a kneeling position between his mother's legs, his hands trembling slightly as they gripped her hips. The adrenaline coursing through the teen's body made him feel like the sleeping woman weighed as much as a doll as he easily lifted those hips, stopping when her inviting slit was level with his crotch. He did his best to keep still and stop his shaft from twitching as he carefully aimed the tapered tip at the center of the sleeping female's petals, holding his breath as he half pushed in and half pulled his mother towards him.
In her steamy dream Diane was panting eagerly as she watched her husband get into position, hoisting her rear before lining himself up and sliding the first few inches of his hard member into her. The piercing cry she let out in her dream was merely a whimpering moan in real life, the member forcing its way further inside her feeling much bigger than she remembered it. Her heat-swollen sex struggled to stretch around it, but the slight twinge of pain was oil in the fire at this point, and Diane writhed impatiently, bucking her hips to signal her man to hilt himself.
In the waking world she remained still apart from a few twitches and tremors running along her curvaceous form, but fortunately the male actually mounting her needed no urging. Her mouth had been amazing, but it had barely prepared Ken for his first taste of a woman, and the teen was sure that if he hadn't just spent himself in his mother's messy muzzle he would have cum before he was even all the way in.
His shaft slid smoothly into her despite how hard those velvety walls seemed to be squeezing around his canine rod, the pink lips of his mother's sex lewdly splayed around the rosy length sinking between them. He finally felt himself hit some sort of barrier when his knot was a fraction of an inch away from the sleeping female's stretched folds. He gave a little buck of his hips, trying to see if maybe he could get a little further in, but his mother just winced a little and he didn't manage to slip in any further.
Probably for the best if I didn't tie with her anyway... he thought, although just the image of his cock buried and knotted in the gorgeous woman below him was enough to make his canine length squirt into that deliciously tight slit. He found it strange since he'd never had a sexual thought about his mother, despite the fact that he was aware she was a very attractive woman. Now the sight of her naked in the lamplight, her cum-streaked muzzle gently parted as she let out little moans and squeaks, inspired nothing but passionate thoughts, each one lewder than the last. Just this once. She'll never know and everything will be back to normal in the morning...
With that thought Ken had shed the last vestige of reservation, holding the sleeping woman's hips firmly as he slid his shaft out of her, the red length glistening with the juices he'd pumped into that velvety slit so far. Her shuddering gasp was drowned out by his own, the teen's tail twitching behind him at the sensation of feminine lips clinging lovingly to every inch of his cock that he pulled out of that tight tunnel.
Once only an inch or two were still inside he reversed direction, sheathing his cock in the slumbering female in one smooth stroke. He once again grazed that wall deep within his mother, drawing a squeak from her even as her sex squelched around his girth. Instinct made up for the lack of experience, and Ken soon found himself panting as he pistoned his cock in and out of his mother, his strokes still slow but steady as the sex he was pumping into began to gush with every thrust.
He moved his hands just a little lower so that they were cupping his mother's round cheeks and he swore he could feel her wriggling just a little into his grip. Her DD-cup breasts looked even bigger as gravity flattened them out on Diane's chest, and the horny teen couldn't take his eyes off the soft globes while they wobbled enticingly as his rutting shook his mother's whole body.
While only cute little noises left her muzzle, in her dreams Diane was screaming and moaning like a whore. The strong hands groping her ass felt wonderful, but the sensation paled to what she was feeling between her legs. Her husband's cock had never filled her like this, the throbbing rod stretching her almost painfully and bumping against her cervix every time her man buried it inside her. But her body was getting what it needed and it was all it mattered now. 
Well, it felt like it was getting it. On some level Diane knew that despite how lucid it was, this was only a dream, and that any time now she'd wake up with damp sheets and the same problem she went to bed with. She only hoped she'd stay asleep long enough to get at least the illusion of having been bred. Just the thought of this being over before she managed to climax made her spread her legs wider and beg for her husband to fuck her senseless.
What was a lusty scream in the rodent femme's slumbering mind came out as a soft mumbling. As quiet as it was, Kenneth's round ears clearly picked up '...uck me...' coming from his mother's cum-drenched mouth. He'd thought she was completely out of it, especially since she hadn't woken so far, but the idea that his mother was feeling, and more than that enjoying this made something click in the teen's pheromone-flooded brain.
His hands moved to Diane's slim waist, since he knew he'd need a good grip for this. Shortening his strokes he began to jackhammer away at his mother's straining sex, showing no restraint or mercy as he unknowingly battered away at the barrier to her womb. The over-stuffed sex gushed and squirted with every savage shove, drenching both rodents' crotches in their combined fluids as Ken pummeled away between his mother's legs.
Diane found her grip on her dream had become tentative as sharp jabs of pain tried to drag her brain from the drug-induced slumber. Taking her husband had never hurt so much, and in truth his shaft stretched her quite comfortably and never came close to bottoming out inside her. In her dream, Diane was squeezing her eyes shut and blinking back tears.
But there was as much pleasure as there was pain, and the rat femme found herself gritting her teeth as her sex clenched up around the pistoning rod, making it seem twice as thick as her sensitive walls milked around it, almost as if they were trying to caress the savage member and calm it down. It wasn't doing much good, and after a particularly powerful jab her eyes flew open, shattering the dream and confusing the still orgasming woman as her vision struggled to focus.
"Wh-wha..." she mumbled, her mouth feeling like it was full of something thick and bitter-tasting.
"It's okay mom, it's okay..." came a panted reply, the voice sounding distant despite the fact that the speaker was directly above her and...
...inside her! Diane still felt groggy, having been pulled back into wakefulness before the drugs left her system, but panic was clearing some of the fog away as she recognized the voice. It was her little Kenneth, holding her waist as he hammered away at her sex. She was horrified but not nearly enough as she should have been. She should have screamed, struggled, ordered her son to pull out of her this instant.
"P-please Ken...you can't... you can't..." she mumbled. To her shame she wasn't trying to say 'You can't do this!' but rather 'You can't come inside me.' And she couldn't even get that much out.
In her defense, her son's rutting was so forceful that every thrust drove out what little air she managed to get into her lungs, and every now and again she felt a sharp pain that almost seemed to be in her belly. She was wondering what it could be when the slap of her son's huge sack against her cheeks filled in the blanks. An image flashed in front of her mind, a glimpse when she'd walked into her boy's room before he learned to lock it before having a little personal time. She didn't see much before averting her eyes but she did remember she saw him gripping it with both hands!
Ken was too far gone now to care that his mother was awake. His was so close now, and with the scent of the woman's heat fogging his mind there was nothing short of a cattle-prod that could have gotten him to stop. Even that barrier inside her seemed to have given way, and the teen could now feel those plum pink lips touch his knot every time he ground it against them. And every ounce of strength he had left was devoted to getting that hard red bulb inside his mother, the boy instinctively eager to feel her velvety walls gripping his shaft as he bred her.
Even though she still felt woozy, her brain struggling to form so much as a single thought as the sleeping-pills and her heat both made thinking a struggle, she managed to read her son's intention in the way he looked at her. She tried to speak but nothing but pants and squeaks got out as her heat-swollen folds received a pounding. Her son's shaft was going further inside her than a male was supposed to go, but the pain was now buried beneath a burning desire.
Her first climax had merely whet her appetite, and the rat femme found herself licking what could only be her son's cum off her lips as she eagerly awaited for another load between her legs. With her last shred of both resistance and dignity buckling, she lifted her legs and hooked them around her son, spreading herself just a little wider as she waited for the inevitable.
Her boy didn't make her wait long. There were a few more bruising thrusts, the teen grunting as his knot splayed his mother's lips but failed to slip between them. It was only when Diane moved her hands down and managed to spread her slick and sore petals that her son's knot managed to push them open far enough to sink all twelve inches inside her.
Diane's eyes rolled back in her head at the sensation of a cock now firmly wedged past her cervix, the bulb at the base growing with her son's every heartbeat now that her pussy was clamping around it. She knew what was coming, but for this one blissful moment she didn't care. Even if she found the will to do so, there was no stopping this now. Ken's knot had barely managed to slip inside her and she could feel it growing even bigger. 
Time seemed to slow for her and even though her son remained still his member was moving within her. Not in and out like before, but the shaft was inflating, throbbing and twitching, her stretched-out sex picking up every miniscule movement as her whole body seemed to tingle. Her pupils shrunk to pinpricks when she actually felt her son's sack twitch against her cheeks, the first rush of hot seed traveling up that canine length before being deposited directly into her womb.
She let out a shaky, almost keening whimper, a sound she'd never heard (let alone made) before. She heard her son, her darling little boy, groan as he began spending himself inside her, his young face a mask of ecstasy as Diane realized he'd given her his virginity even as he took her. The knotted shaft inside her felt like nothing ever had as it throbbed with every pulse of thick sperm, her body eager for more no matter how much the young rat shot into her.
She didn't even realize one of her hands was drifting lower until the fingers slid across her abdomen and felt a slight curve to her normally flat tummy, one that was growing subtly larger with every twitch of her son's heavy pouch. The digits trembled as they drifted lower, until they reached her sex. She gasped as she felt her lips stretched so taught she could feel the hard knot just past them. 
The touch had left her panting, her toes curling as she realized she was on the edge of a massive climax. She needed just a little push, and when her deft fingers found her clit she knew she'd found it. The sensitive little nub was pressed against the swollen knot, and a few gentle rubs were enough to push her over. She bit her lip just in time to stifle a shriek she was sure would have made the other vacationers call the police. Her body shuddering as her stuffed cunny still did its best to milk the shaft that didn't need any help pumping her full.
As she was coming down from her mind shattering orgasm Diane felt a slight, and very specific twinge in her tummy. One that usually meant her eggs had left her ovaries, but she realized it was something different this time. Her womb was full, to the point that she looked like she already had a little bit of a baby bump, but with that fat knot sealing her off, her son's seed was flowing into every nook and cranny inside her.
In a post-orgasmic haze she stretched out her hands towards her son, beckoning him towards her. With her legs still wrapped around him, Ken gently lowered her down and then laid himself on top of her, his mother whimpering quietly as this caused his knot to tug and shift within her. She could feel her son's chest working like a bellows from his exertions, and his heart beating away within it right next to hers.
Ken's face was now buried between her lush breasts, and as his muzzle found one stiff little nipple Diane coed in sheer delight when he began to kiss and suckle her. She wrapped one hand around his back while the other pressed his face into her teat, the two lovers forgetting everything for a brief moment while they savored this new level of intimacy they found themselves in.
*******
Diane set the glass down and immediately tossed the packaging away at the same time she forced the pill down her throat. She pulled the strings of the garbage bag tight and immediately went out to throw it away, erasing the last of the evidence of the incident with her son. She got the Plan-B pill the moment they got back to civilization, having little doubt she was pregnant after the night spent with her son.
She blushed as she remembered the whole thing, and the mixed feelings she had. She knew she should feel violated, and she did a little, but it was still her child, the growing boy who loved her as much as she loved him. The moment he'd walked into the room reeking of her heat he didn't really stand a chance. Neither of them were really to blame.
An image came back of him in her embrace, nuzzling her breasts even as his shaft continued pumping within her. She thought she was going to burst until that knot finally shrunk enough to slip past her sore lips. She remembered quickly slipping the hand that had been gently coaxing her to several more climaxes over her well-bred slit, expecting a torrent of watery canine seed to gush out of her the moment her son's shaft left her. To her surprise the load oozing out of her was quite thick, and she could still recall the sight of the pearly strand of the syrup-thick goo connecting her thumb and forefinger as she examined it.
Ken had been quite attentive, dashing off to get a towel, placing it under her rump and gently using a washcloth to clean away everything that her body couldn't keep inside it. But it kept more than enough. Her husband never found out she'd forgotten her blockers because her heat had been quenched that night. When they got home she'd thrown herself at him, taking the stunned male to heaven and back to try and ease the guilt she felt.
To her relief making love to her man felt just as good as it always did. He was loving and gentle, and he knew her body well enough that it made up for the fact that he wasn't endowed in quite the same way as Ken was. But that didn't matter. She was ready to put it all behind her and continue her life as usual. Ken was also acting like nothing ever happened, but every now and again Diane caught him giving her a look that told her he'd come running if she were to call.
I just have to keep a grip on my self. she thought even as a memory of a knot growing inside her made her rub her thighs together. And if I fail, at least it's not the end of the world...