Chapter 5 - The greatest achievement of mankind

by MadGenuis

Granted that the term "sometime" is loose per definition, Keith still had some kind of expectation that when his sister used it to describe the time of their next 'test' that she had meant "soon", and had resolved to abstain from masturbating until then so that when the time came, he would be positively overflowing with sexual energy. He was determined that next time they were to have a 'test', which would likely once more include him banging her magnificent little pussy, it was going to be something special.

This, however, turned out not to be quite as easy as he had figured it would. For one thing, Keith and Emma's last 'test' had probably been the single sexiest thing the thirteen-year-old had ever experienced, yet he had not gotten the release that he so desperately craved... and it had even been two days since the 'test' before that, and he had not masturbated in the meantime, meaning that he was already pretty damn horny. Already the morning after having made the silent pledge to abstain from pleasuring himself, Keith was hurting, especially in his testicles (if he had known the term, he could have said that he had blue balls), and spent the day walking around with an almost constant erection, which ached incessantly. It was incredibly hard to ignore, but somehow he managed.

The first day, that was. Then came the second, and third, and fourth... days slowly turned into weeks, and by the time nearly twenty days had passed, the very sight of Emma, no matter her appearance, nearly drove him to find the nearest leg to hump like a dog. It was horrible, but no chance to get Emma alone presented itself. To be frank, after the first fortnight of celibacy Keith was more than ready to break his promise to himself to finally get some sweet relief, but when he tried it turned out that he could not think about anyone else than Emma, and thinking about her made him remember his inability to finish last time, which inadvertently prevented him from finishing again.

He was pretty desperate by then, having no concentration left for school as he just spent all his time poking the underside of his desk with his boner; out of curiosity he checked one time when he was alone in the classroom, and found that yes, his pecker was indeed hard enough for him to tip his desk over on two legs with. He tried fantasizing about the girls from school, but after their wicked prank (the one that initially drove him to violate Emma) all thinking about them did for him was to effectively kill his erection.

At the three-week milestone, Keith had been driven so far that he locked himself in the bathroom and decided that he was simply going to keep at it until he could unload all that pent-up tension within himself. He recalled nearly every dirty fantasy he had ever had and replayed it in his mind with just about every girl he knew, but even so still managed to spend so long out there that his father eventually knocked on the door and asked if he was taking a bath, and if he was, to hurry up so that someone else could use the toilet.

Desperate, Keith had kept jerking it off for several minutes even after that, until the woman he least expected to visit his mind came by: his mother. In Keith's mind she was very sympathetic with him about his troubles and (ignorant about his relationship with Emma even in his imagination) offered to "teach him about sex". Unexpectedly, this had him erupting like a geyser in a matter of seconds, launching four record-large and -thick shots of semen high into the air which splattered on his knees and the tile-floor of the bathroom. Sighing with immense relief, the boy decided that there was probably no evading by now that he was thoroughly twisted in the head, and went to cleaning up before the rest of the family got even more suspicious.

This kept him going for a few days, as Keith discovered that sex fantasies about his mother actually turned him on very much, having the same forbidden feel to them as any about his pre-teen sister, though his mother was still not as exciting as Emma. Sure, his mother was pretty hot for a thirty-something-year-old, but she lacked that childish innocence and petite charm in Emma that drove him mad. It was enough to give him a few orgasms, though, and for that he was grateful.

He decided that this could not go on, though. His sister was one thing; she was in on this, and wanted the 'tests' too. His mother (although she was very eager in his daydreams) was not, and he felt fairly certain that it would have dire consequences if he ever propositioned anything of the sort to her. He needed something else to fantasize about � fast.

That was the day his class were doing some project for which they needed to use computers, and one of Keith's classmates tried to pull a new nasty prank on him by sneaking over to Keith's computer while he was gone, open an Internet browser and went onto some address or another that ended up displaying several images of naked women near the top of the window. His classmate had probably hoped that a teacher would notice and Keith would get punished, but luckily Keith caught his classmate in the act and went to close the browser before anyone saw. He did note the address, though.

When he got home, Keith checked that site again, this time on his own computer, in relative privacy. As it turned out, that malevolent classmate had inadvertently saved Keith from having to resort to masturbate to mental images of his mother. It was a free porn-site, containing links to preview-videos of probably hundreds of others, featuring just about every fantasy and fetish ever conceived by mankind.

Needless to say, there was no lack of inspiration after that, and Keith even upped his masturbation frequency to once a day instead every two or three days. He found that he really enjoyed watching girls (or young women, as it were - although he could get excited about his mother, other mature women freaked him out a bit) pleasuring or even just showcasing themselves, and became a connoisseur of all the wonderful things that could apparently be fitted into a vagina. He skipped all the videos about pleasuring the anus, because he had no interest in doing that, and absolutely no interest at looking at it. After a while he also discovered lesbian porn, which was just as good as solo-girl porn, and even developed a certain fondness of watching girls bang each other with strap-on dildos. He did not watch any videos with men in them, though, as he found that he was thoroughly grossed out by men in general, even if they were busily doing some hot chick.

Now, aside from having sweet, sweet porn to keep himself somewhat satisfied during this time of sexual drought, Keith also learned a few very useful things, such as numerous different positions girls wearing strap-on dildos (and thus presumably also heterosexual couples) could have sex in. He learned that he was actually doing pretty well girth-wise, even if his penis lacked length, and that he apparently admirable sexual stamina. And, perhaps most importantly, he learned a whole lot more about the female body and sex, such as what a moist vagina meant, or why nipples got hard, and what a female orgasm looked like. That last one rather shocked him; he did not realize it until then, but through the enlightenment of Internet porn, Keith realized that he had actually driven Emma to her climax several times already. That thought most definitely helped him finish masturbating right quick that day, and served as additional motivation to finding a moment alone with his sister.

Finally, about six long weeks after their last 'test', the opportunity Keith had waited for appeared. Both of their parents were going out shopping, Mike was visiting a friend, and both Keith and Emma were staying home alone. Upon coming to the realization that he was going to have Emma all to himself for several hours, the thirteen-year-old first nearly whooped with elation, then spent the time until his parents left vividly imagining charging over to his sister, pushing her to the ground and pounding her like a wild animal until one of them passed out. He had coincidentally been saving up orgasms (part of him just figured that the longer he waited, the more was stored) for a couple of days, and had meant to masturbate today, so he was horny even before hearing this. This, he had decided, was going to be a 'test' to remember!

When he finally found her she was in the kitchen, making herself a sandwich or something, her back turned to him as she leaned over the counter, applying butter to a slice of bread. Keith's throat went almost instantly dry: she was wearing a pair of pinkish sweats that fit her somewhat loosely, but because of the way she was bent over they still fell to frame her petite little ass beautifully. She had these pink little socks on that seemed adorable for some reason, and a moderately baggy T-shirt that seemed to enticingly depict her slender shoulders, but left the rest of her frame to his imagination and memory. She wore her hair loose, and somehow Keith could not shake the feeling that this was definitely the most attractive he had ever considered her... or maybe he was just extremely horny right now. His pecker felt hard enough to be used as a chisel.

He moved up behind her, trying to walk silently as to surprise her, and leaned in close to her ear, breathing into it as he spoke.

"Wanna go... upstairs?" Keith asked, and although he had meant to sound smooth and seductive, the dying bashful side of him seemed to make a persistent last stand, causing his voice to fail him halfway through the sentence. "For a... you know, 'test'?"

Emma hesitated a moment, but did not pull away from her brother or push him away. She simply kept concentrating on her food. Impatiently, Keith gave her butt a little shove with his pelvis to tell her of the fact that his erection was right there, practically mashed up against her and very ready for action. Horny as he was, even just grinding against her felt amazing.

"After I've eaten," she stated flatly, then took her food and moved out of the boy's grasp, heading into the living room.

Keith was left behind, feeling completely lost. This was not an outcome he had prepared himself for... but she had accepted. That was something... maybe?

Confused and almost dazed, he followed Emma out of the kitchen, through a short hallway that lead right past the stairs from the top of which he almost thought he could hear their beds beckoning, and into the living room where he found his sister already sitting in the couch - the very place in the couch where they had masturbated one another last time they had been together - and ate her food at a leisurely pace. Just looking at her from a few feet away, impatiently waiting for her to finish, the boy felt convinced that she was eating slowly just to mess with his head. It worked. His erection made a very visible tent in his pants, and she just sat there, eating as though nothing in was wrong.

"You standing there looking at me doesn't make me eat faster," the girl said after about a minute of the two of them waiting and eating respectively. "We agreed on doing it in your bed this time, so go get ready."

Needless to say Keith did not have to be told twice... but then again, he figured as he pretty much flew up the stairs towards his room in but a few half-leaping strides, at this point Emma could probably make him do just about anything to get her to participate in a 'test'. As it was it barely took him ten seconds to get from where he had been standing next to the couch in the living room to the short ladder that lead up into his bed, and hardly a second to hurtle up the ladder and onto the bunk bed mattress after that.

"Go get ready," she had said, and Keith gleefully replayed the words in his mind, but then abruptly felt the eagerness drain from him when he realized that he had no idea what that meant. Get ready... how? For a moment he just sat there in his bed, trying to think of something to do with this time of preparation. He milled about, sorted through and moved some things in his room, particularly in the vicinity of his bed, but did not really accomplish much of anything because his mind was pretty much focused on what he intended to do... for which he did not really need anything aside from himself and his sister.

In the end Keith just crawled back into bed and stripped himself naked, after which he lied down in what he hoped was a confident and attractive posture; a plan that was pretty effectively ruined after a couple of minutes and the initial excitement had passed, and the lack of inspiration had his erection fade quickly until it was reduced to its very unimpressive soft state in which it was only an inch long and looked utterly ridiculous.

By the time Emma actually arrived at Keith's room, she found her brother naked in his bed, sitting at the top of the ladder wrapped in a blanket, looking down at her sheepishly. In the end, even after this vast experience with sex the boy felt he had accumulated over these past couple of months since their first 'test', Keith was still just a boy, bashful by nature, and the only romantic experience he had ever had remained - quite disturbingly, he realized - to be with his little sister.

The act of wrapping himself in a blanket had somewhat reminded him of when he and Emma had done so together last time, and had secretly masturbated one another in the presence of the rest of the family, and thus had actually served to have his erection slowly recover, even if only some of the way.

Then Emma saw Keith waiting for her, naked in bed, and hesitated. For a moment the boy grew utterly terrified that his sister had perhaps changed her mind, that this 'test' would never happen, that his boldness had forever ruined their relationship... until Emma reached down to her waist, grabbed the hem of her T-shirt and pulled it over her head, leaving her torso naked. Then she pulled off first her socks, then her pants, revealing a pair of cute little white panties, which she finally shucked as well.

By the time Emma stepped out of her panties and went to climb up into her brother's bed, the sight of his sister disrobing and the thought of why she was disrobing had already revived his erection almost completely, and he once more found himself feeling anxious and fidgety, so eager to just reach out and feel the soft skin he knew the little girl before him hand, to caress her shapes, and to... to pretty much continue where he had left off the last time they were together like this.

Soon Emma had seated herself on his bed, her legs beneath her and her hands on her knees, her back straight and her gaze turned to her brother, its expression seeming mildly curious, a small smile gracing her lips but otherwise revealing nothing of what went on behind those pretty little brown eyes, her brown locks of hair falling gracefully upon her slender shoulders. It was the same pose she had assumed several times before during these 'tests', Keith realized, but somehow he thought that this time was different; like there was a new kind of beauty to her, almost poetic, that warmed his heart and hardened his dick. Something was different about her from last time he had seen her naked, but he could not quite seem to figure out what.

Noting the impatience that briefly flashed across his sister's eyes, Keith decided that this would have to be enough gawking for now and that it was time to get down to business and involve her more in the excitement of the situation than just letting her be the passive object of his desire. Throwing off his blanket to crawl over to Emma, thus revealing his own scrawny frame and eager boner to the other, Keith reached up with his hands to begin the by now almost ritualistic caressing of her body, starting with his hands tracing the shape of her collarbone and shoulders, feeling down her sides where he could feel her ribs plainly, letting his hands wander to her chest to -

By the time Keith had gotten to where he would usually have just gently stroked his sister's chest and played with her nipples a bit, he abruptly froze as he felt something like a... a lump, was the best way he could describe it, under her skin in just the immediate area around both her little areolas. They were very small, perhaps three or four inches in diameter and just barely thick enough that it prevented him from feeling the ribs behind them, but they were definitely there.

"Emma!" Keith gasped, breathless with excitement as he first removed his hands to confirm that these little swellings were indeed slightly visible, and then went in to gently rub and knead the little softly padded areas. "You've... you're starting to grow breasts!"

"Yes," his sister responded in a thin voice, nodding her head. Keith was almost ecstatic, gently rolling the tiny budding breasts under the palms of his hands, tracing their outline with his fingertips, groping them with his whole hands as if intending to grab onto them. He neglected her nipples a bit to explore these new wonderful toys of his, leaning in to first lick each breast until they were slick with saliva, then he placed his lips over her the entire span of her right breast and sucked carefully, as though to draw the entire breast into his mouth - and with a little, almost soundless pop, he actually succeeded!

Giddy with how well this was already turning out, Keith let his sister have her newly acquired boob back, only to concentrate his efforts on her tiny right nipple. He went in and licked it, even bit down on it with his lips, let his tongue play with it until he felt it stiffen at least some of the way through his attention. Then he leaned over and gave the left nipple the same treatment, all the while letting his right hand wander up to play with her now-vacant right breast and nipple.

By the time Keith leaned back, feeling that he had achieved as much as he possibly could by playing with her chest, both of Emma's nipples had gotten hard and both her beautiful little breasts were coated in a glistening layer of saliva. The girl's breathing had gotten a little faster, he noted, and recalled from what he had seen that this meant that she was getting excited as well.

Feeling much bolder knowing that he had her approval thus far, Keith went back to work, reaching out with his hands to give both of her little tits an affectionate squeeze before he let his fingers crawl downward, caressing her stomach and navel, then let them wander to her bony little hips, stroking, almost tickling everywhere they went, before they continued down her silky thighs and down to gently rub her knees.

When Keith got that far, Emma seemed to recall how the past 'tests' and progressed and started to lie down on her back, straightening her legs as she did so, but before she could settle in properly her brother had an idea.

"Try turning around," he croaked past his dry throat. As incredible as it was, he felt almost as nervous and shook almost as bad as at their first 'test'. "Lie on your stomach."

She did, and Keith was rewarded with the sight of the two soft, flawless little globes of her buttocks, which he immediately found too beautiful to resist touching. He leaned in and first gripped her ass firmly, then gently kneaded her butt cheeks with his fingers, spreading them and squeezing them together to feel their supple tissue beneath his hands as much as possible. He then let his hands work their way further down steadily, caressing every inch of the back of her thigh as he moved over it, until he got to the back of her knee. When he got there, he gripped each knee firmly, then moved them apart, causing Emma to spread her legs for him. She did not resist at all, but actually helped moving her legs, which exciting Keith to no end. Just about anything she did to actively further the advancement of these 'tests', he found, just seemed incredibly sexy.

As her legs parted, Keith almost expected to hear a choir of angels in reverence for what came into view. Up high was her little (to Keith) unattractive rosebud, puckered in its eternally inhospitable appearance that was in direct contradiction with how much he knew Emma enjoyed having things put in there, and below it, looking perhaps even more amazing from this angle than when his sister had been lying on her stomach, was the wonderful, delicious vagina.

Keith was a little shocked when he saw it, because initially he had thought of it as "my vagina", which he found a little disturbing. It was his sister's, after all... but somehow, he could not help it but feel possessive about this magnificent thing that he had been the first one ever to touch in the best of ways, which he had deflowered, which he had been inside. Even more surprisingly, he found that it there was also a feeling of rightness about thinking of his own sexual counterpart as "Emma's penis". He felt that she belonged to him, and he to her. It was a nice feeling, if a bit unexpected.

With renewed fondness for this almost sacred place on his sister's body, Keith moved in and gently caressed her vulva, tracing his fingers around her slit but being careful not to touch her labia. He moved in only briefly to flick a fingertip at her clit, but then let his hands dance away again before returning moments later, prodding her little bean, and then hurrying away again. He noticed her entire body squirming slightly as he did this, and he felt all her muscles tense up whenever he touched her clit, and knew that he was on to something good. Her snatch was also going from moist to wet very fast, until her juices were actually running from it in little droplets, traveling past her clit and down the curve of the front of her pelvis, which would have lead up to her stomach had the mattress not been in the way.

When Keith saw one of those droplets escape the folds of her nether lips, he could not resist the urge to reach down deftly with a finger and catch it just before it would have reached the mattress, taking it onto his finger, which he in turn put in his mouth.

The familiar taste of her pussy was too much a temptation, and Keith lied down with his head between her legs to start lapping at Emma's box like a dog, letting his tongue press lightly against her labia and push them apart just enough that the tip of his tongue could slip into her. He only did so briefly, though, before he regained control of himself and sat back up. Stick with the plan, Keith. Stick with the plan.

Reaching down with his hands he let his fingers massage her vulva some more, but only briefly before he let them concentrate on playing with her clit and labia, secretly working at smearing his fingers thoroughly in her juices.

"Could you..." he began as he had an idea, but somehow what he was about to suggest felt perverted and naughty, even more so than what they had been doing together thus far, although from a logical point of view there were probably few things more so than putting his penis in his ten-year-old little sister's vagina. Regardless, he found that he had even more difficulty saying this than he usually had speaking during their 'tests'. "Could you moan? Just a little?"

From the current angle Keith could not see Emma's face, but when she spoke she sounded slightly irritated, and somewhat out of breath. "No."

"Please?" He slipped his index finger inside her, letting it explore the inside of her vagina a little. He had thought that it was pretty hot when the girls in porn moaned from pleasure, and when they practically cried out loud at their orgasm. He had figured that it was a rather common reaction, since pretty much all the porn-actresses did it, and thought it would be sexy if Emma would do it, too.

"I don't want to," his sister maintained. Her tone sounded adamant, so Keith decided that the subject was not worth pursuing. It was just kind of hot, anyways; not nearly as exciting as the actual sex and stuff. Besides, even now he worried that he might end up doing something that would push Emma away, scare her or otherwise make her resent the 'tests' so that they might not happen in the future... or worse, she told someone about them. That could not happen, for both of their sakes.

Once Keith's fingers were nice and soaked in Emma's juices, he removed his right hand from it, letting his left hand continue playing superficially with those heavenly folds. He put his now-free right hand up by her anus, and started gently massaging it and the area around it, methodically smearing it with her own pussy juice.

When he slipped the tip of his index finger into her ass, he noted how both her sphincter and pussy clenched momentarily before both relaxed, allowing him to continue his administrations. He only fingered her ass for ten seconds or so, though, before he withdrew from her entirely, earning a disappointed sigh from his sister.

She started to sit up, but Keith gently but firmly pushed her back down, keeping her on her stomach. "Wait a moment," he urged her, half-turning to examine some of the things he had put in his bed during his time of preparation. He picked up two items, then turned back, a smile on his lips.

Leaning back down to her posterior, Keith took one of the items he had brought - a small, thin, red plastic sausage - and prodded it first cautiously, then more firmly against her pussy juice-lubricated anus, slowly prying open the tight hole to admit the toy passage. At this, Emma apparently was so confused by what she was feeling that she raised herself onto her elbows to look back over her shoulder at what her brother was doing to her, only to witness him shove about half of the almost six inch long toy sausage into her butt.

At first her eyes just sort of widened while she held her breath as Keith began moving the toy in and out of her rhythmically, her expression unreadable. Then he brandished the other item he had brought with his other hand - a small plastic banana - and smiled at her lasciviously. If at all possible, her eyes seemed to widen even further. The banana was probably some eight inches long, somewhat pointed at either end as bananas are, and perhaps a little over an inch at its thickest. It was significantly larger than the sausage, and longer than Keith's member even when it was the biggest, but did not have the overall girth of his penis.

Even so it certainly got Emma's attention as he began slowly inserting the banana into her pussy, spreading her nether lips even as he kept inserting and extracting the plastic sausage in her ass, pushing it a little farther in with each insertion.

By the time the banana had been pressed into her nearly to where it was the thickest, Emma finally released the breath she held in a long, ragged exhalation, her eyes shifting curiously and her eyelids fluttering. As Keith began working with both the toys in her holes, she even let out a little trembling whimper, followed by a strange drawn-out humming noise, like she was really thinking about something hard. Just, "hmmmmmmmmmm."

But even as she seemed to keep her lips tightly pressed together to prevent any sound from escaping her, little whimpers and hums were still audible with irregular intervals, and after a minute or two she began doing what Keith could only describe as moan through the nose. It was not long before her arms apparently failed her and she had to relinquish looking at herself being played with, and stretched out on the bed once more.

Keith really went to town on his little sister by now, trying to remember how the women in the porn movies had done this and mimicking it. As he thrust in and out he made sure to turn and twist his wrists a bit every now and then, turning the toys so that their angle of entry was a little different with each thrust. Admittedly, this part of the 'test' was not what he had been looking forward to, and it was not really for his sake at all. It was more a case of the boy wanting to make sure that Emma got some pleasure from this session, and not just him, as he was not entirely certain that she would actually approve of what he had planned to make himself cum.

Still, playing with her like this was undeniably very hot, and he was glad that both of his hands were occupied, or he might have unconsciously started masturbating out of sheer horniness. As it was, his sister's cute little noises and the sight of the plastic sausage and banana pumping into her butt and pussy respectively was more than enough to keep his tool nice and hard, positively throbbing with pent-up sexual energy. Hell, even his testicles felt tingly, which was unusual for him. They had only ever hurt or otherwise felt uncomfortable, but now they kind of felt... pleasant.

After a while of playing, Keith angled the banana so that even as he kept pushing it into her vagina, it also mashed up and rubbed against her clitoris. This finally had her part her lips and produce some real moaning, and with an adorable little sound like "guh", Keith noted that it became significantly harder to move the toys, and virtually impossible to push the banana any further in.

Once Emma relaxed enough for her brother to retrieve the toy food from her holes (causing each of them to quiver slightly once more), Keith could not help but to smile at his beloved little sister as she lay there, panting heavily from what he knew must have been her orgasm.

"How did that feel?" he asked her, the words passing his lips surprisingly easily considering how hard it had been to speak up until then.

"It was..." Emma began breathlessly, then held a ponderous pause while she kept gasping for air. "Special. But nice."

Keith nodded to himself, his smile widening. "That's called an orgasm," he told her happily. He paused. "I thought you said that you weren't going to moan?" he teased her, though not unkindly.

"Shut up," she breathed. She did not sound angry. There was a moment's pause. "Are we done?"

"Not if I get to decide." He almost laughed when he heard the near-disappointment in Emma's voice. She wants more! She actually wants more! "I'd like to try what we did at our last 'test' again, but a bit different this time."

"Okay." Emma began moving to lie on her back, but like last time, Keith stopped her with a gesture. Having somewhat caught her breath by this time, Emma furrowed her brow in confusion. "What, then?"

"I was wondering if you could, err..." There was that old tightening of the throat and the knotting stomach! He knew it could not be far away, and now it seemed all those old symptoms of his anxiety and bashfulness returned to hinder him once more. "Somehow... be on top?"

His sister's brow furrowed more. "On top?"

"Yeah, like you could... you know, straddle me. Down there." He pointed to his crotch, where his erection waved at her eagerly.

But Emma shook her head. "No."

Keith bit his lip. He really did not want to beg, but... "What if next time, we do whatever you want to do, if we do what I want this time?"

"If we do whatever I want at the next 'test'?" she muttered, and something about the way she drawled the word "I" and that creepy little smile of hers made her brother's butt clench in fear for what she might already be planning. "Well... Okay, then."

Delighted that he had talked her into doing this with him, Keith hurriedly lied down on his back in the bed, his erection hovering just above his abdomen, its tip quivering in the air just above his navel, his entire body shaking with eager expectation of what was about to happen. Even as Emma somewhat hesitantly crawled by past her brother's legs, one leg on either side of his, Keith's mind was already stuck in a loop of just thinking Yes, yes, yes, yes, yes, yes, YES!

Soon, Emma's groin was hovering directly above Keith's pelvis, the folds of her vagina so close to his penis that he could actually feel the warmth emanating from it, and after about two seconds he felt something wet drip onto his shaft, and then quickly run down its length until it came to nestle in a little pocket-like hollow made in his scrotum right between his balls. Just knowing that Emma was still so wet from being played with that she was positively dripping was enough to make Keith's dick twitch all over again. It throbbed as mightily as ever, positively trembling with eager impatience to be allowed to return to that wonderful place it had only visited once before.

"How do I..." Emma began, but even before her older brother could come to her assistance, she had already reached down with her right hand and taken a hold of his member, and pulled on it so that it ended up pointing upwards, the red eye of its head staring directly into the wet folds of her flesh.

The siblings gasped in unison as Emma lowered herself onto him, her weight pushing the rigid penis farther and farther into her, all the way to the hilt when she was resting her pelvis on his. She took a moment to adjust her legs, planting her knees firmly in the mattress on either side of him, and then, with an expression of utter concentration, began raising herself up and pushing herself down on him, quickly finding a very comfortable bouncing rhythm.

For almost the entire first minute of this exercise, all Keith could do was to lie passively and stare, spellbound by the sight of his shaft disappearing into and reappearing from his sisters beautiful pussy. In that other position last time, which he had learned was called the missionary position from the porn videos, he had not been able to actually see what was happening down there, but like this he had a wonderful view of it all. He could see his dick getting slick with pussy juice, the magnificent nether lips of the vagina spreading and accepting his girth, see the two sexual organs merge with and emerge from one another... all while he felt that wonderful warm, moist tightness envelop him. It was beyond wonderful.

And best of all, this time Keith did not get exhausted from doing it, so he could actually enjoy every second of it. After half a minute or so of just watching his sister bounce on his dick he reached up with his hands and gently caressed her hips, using his arms to help her move and guide her rhythm to be more regular. After a full minute, he grew bold enough to start meeting her bounces with upwards thrusts, which quickly earned little gasps and whimpers from Emma.

It was good times, but after about three minutes or so of heavenly bouncing, Emma suddenly exchanged her until then vigorous bouncing with a short series of small movements that barely even qualified as wriggling, and then stopped moving altogether.

Keith looked up at the girl with an unspoken question in his eyes. Oddly, he did not feel all that opposed to her having stopped moving... probably because where she had paused, his member was still buried within her to the hilt, wrapping it all the way in the sublime folds of her flesh. He wanted her to continue, though; just being inside her was great, but what they had done before that was heaven.

"I'm getting tired," Emma breathed, regret in her voice. "I... I don't think I can keep this up much longer."

Damn it! Keith thought, gritting his teeth. Well, of course there had been a fair possibility that being on top tired her as much as it tired him, but he had hoped that was not the case. He had to figure out a way to do this with her without either of them getting exhausted...

"I have an idea," he finally said, reluctantly gesturing for Emma to get off of him. His member slid out of her pussy with a wet "flop", practically drenched in her juices, and felt suddenly very, very cold and lonely. He sat back up. "Try getting on your hands and knees."

Emma complied, apparently getting the fact that she was to turn her butt his way on her own, and presented him with the globes of her buttocks once more, along with a great view of her pussy.

Feeling his member twitch impatiently, Keith wasted no time; he got on his knees and moved up behind her, gripping his own dick with his right hand while grabbing his sister's hip with his left, and quickly guided it to her entrance. He pressed against her carefully until he was sure that he saw her nether lips begin wrapping themselves around the head of his dick and felt the familiar warmth of her flesh begin to envelop him. Then, once he was confident that his aim was true, he let go of his penis and gripped both Emma's hips... and thrust in.

It felt absolutely divine to be back inside her, and Keith could not help it but to give a happy little sigh even as his sister gasped from the sudden intrusion. He held still for a moment, just enjoying the feel of the two of them having merged like this, and then he started moving.

This position, he realized delightedly, was just as handy as the previous one in terms of visual aid... or at least it was for him, whereas Emma could not see anything, facing the other way. But when Keith looked down, he could plainly see his member going in and out of his sister's tight little pussy. Not only that, but it somehow felt like he was closer to it like this than he had been lying down... and like this, he decided the pace, he moved how he wanted, and he knew that it was his will that thrust his penis into her.

He kept thrusting, slowly at first, but as the good feelings kept intensifying he picked up the pace quickly, each inward thrust faster and harder than the last, until each merging of dick and pussy produced little slaps as his pelvis hit her butt, and Emma let out little moans and whimpers simultaneously with each insertion.

For a while Keith just kept this up while lovingly caressing the beautiful butt that was placed conveniently right in front of him with his hands, but after several minutes, Emma fell from her hands to her elbows, then down until her shoulders were resting directly against the mattress. Keith only managed to grab his sister firmly by the hips just in time to use his arms to keep her behind in place, even as her legs began to grow wobbly.

"What is it?" he panted, although he kept thrusting into her even as he spoke. It was not that he was anything less than sincere in his concern for her, he could just feel his orgasm approaching in the distance and did not want to stop and have to start over again. "Did you get tired like this, too?"

"N-no," Emma whimpered, letting out little half-cries each time he entered her. "It ju-ust sta-arte-ed to feel real-ly good." Listening to her speak while he was pumping into her seemed extremely sexy to Keith, and he felt his climax get closer. "I thi-ink I'm go-ing to ha-ave anoth-er of tho-ose orga-asms," she gasped.

And sure enough, within seconds Emma let out a long, almost melodious moan like "ahhhhhhh", and Keith felt her pussy clamp down hard on him, squeezing his dick so tightly that he could barely even move, massaging it lovingly as though her vagina was hugging and thanking his penis. Keith swallowed past his constricted throat, pulled halfway out and then pushed all the way in, and -

"Oh goooood!" he groaned, feeling his entire body spasm in the most powerful climax he had ever experienced, his hips almost moving on their own, slamming into his sister's pussy in repeated little twitches as if in an effort to get as deep as possible. It was an orgasm so strong that he almost started crying from the pure pleasure of it, and he could not help but to feel immense satisfaction as he felt his cum shooting into his beloved sister's depths.

He held himself and her still like that for a moment, both of them panting from their individual orgasms. After several seconds of just sitting still, when Keith's massive orgasm finally subsided and his dick started softening and shrinking inside her, he pulled out, and they both just sort of collapsed in his bed, gasping for air.

"That was..." Keith began, but fell silent, his mind so blown by all the pleasure that he could hardly even think.

"Great," Emma finished for him, and he nodded his agreement. They lied back, basking in post-coital bliss.

After a couple of minutes of this, Emma began to sit back up, but as she did so she abruptly froze. "What is that?" she asked, fear in her voice, as she pointed down at her pussy. Keith groggily raised his head to see a mixture of his semen and his sister's juices dripping out of her snatch and running onto the mattress in thick globs.

She looked at him. "Did you...?" He smiled. Her eyes widened. "Wow. That's... wow."

"Yeah," Keith agreed happily. "Yeah, it is."

After wiping herself clean in Keith's blanket - which Keith really did not mind because any reminder of this 'test' was more than welcome - Emma climbed out of her brother's bed and began to redress, although she still seemed a little unsteady on her feet.

Keith just remained where he was, still caught up in how wonderful it was to finally have achieved what he had wanted ever since that last time.

"So, remember that in the next 'test', we do what I want to do, right?" Emma reminded him from beside the bed. Keith gave her the thumbs up to confirm their agreement without raising his head. "Then I decide that it will be tomorrow, in your bed. Okay?"

Another thumbs up. Oh yeah, whenever and wherever she wanted, Keith was more than happy to oblige.

"It's a date, then." And with that, she left him to his blissful stupor.

"I love you," he told her quietly, much too quietly for her to hear now that she had exited his room. Tomorrow. Life was good.