Humanity 2.0, Year 001, Day 022

"God, it's huge... I had no idea, Ben. Where were you hiding this monster all those years?" She continued to stare at it, not really hiding her excitement. I could see even under her loose blouse that her nipples were standing up. I flexed my dick again, making it pulse. She blinked, and seemingly without thinking, her hand went to my length. Just like that, grabbing her own brother's bare, stiff cock. She couldn't actually get her fingers all the way around me, I remember; she knows I like when she tries to, though, even now. "I've never seen one like this... even in porn."

"It's you making it that big, you know." I smiled as she looked up at me, and she knew I was telling the truth this time. There had been a few cute girls I saw in the lobby before I came up, but it was definitely she who had made me hard.

"The truth comes out." She gave me a big grin, which then vanished as she seemed to suddenly realize something. She shied back somewhat, but her hand didn't leave my dick. "I'm sorry... you must think I'm sick. I just felt like I had to see it. You know, like something every girl wants to see before they die. I'm sure guys want to do the same with girls with big tits or something."

"I like small boobs too, actually... like yours." Before she could react, I took her head in my hands. "Besides, I have a story better than even that. I got my hot sister to play with my dick. Most men can't say that... not that I'm telling anyone."

She blinked and looked up at me, her eyes wide like she just now realized what she was doing. "Oh my god. I'm sorry, Ben – um – I-" Her hands came away, and she clasped them together in front of her mouth. "I'm such a sicko. I can't believe I did that." Still, she didn't get up and move away.

"You're not. Even if you are, we both are." I guided her by the shoulders to the bed, where I sat down on its edge and pulled her toward me. I made her sit on my lap, the towel now forgotten on the floor. No longer wanting to hold back, I stroked my arms up and down her sides, over her clothes.

She had kicked off her sneakers without really thinking. My hands drifted down to her ass, cupping and squeezing the taut muscles beneath. So much for my half-formed plan to make it with that uber-hot blonde Nina chick upstairs first; here my sister was, right in front of me, like putty now. My cock raged at me; it wanted to claim her. My fingers found the hem of her blouse. "Em... I'm going to take this off."

"Okay... why, though..." It was almost like she was a bit drunk, but without any of the associated clumsiness or other side effects.

"Well, like you said. Guys want to see girls' tits. Ante up." She nodded, still acting a little out of it as the pheromones made her head swim, sealing incestuous desire within her thoughts. Together, we pulled her blouse off her. Beneath, she wore a simple cream-colored bra, cupping her smallish tits tightly.

My hands stroked her skin some more, and our eyes met. She leaned in toward me, and our foreheads touched. I smiled. "I'm going to take everything else off."

"Then I'll be naked." It wasn't a rejection, exactly, the way she said it; it was more like she was just making a confused statement. The power always made girls want the same thing, but I figured out later on that the specifics of how it affected their minds were unique to each individual.

"That's right... like you should be right now." I unbuttoned her jeans, and soon she was down to only her underwear. She seemed quite concerned suddenly that she still had her socks on, and worked on taking them off as I came around behind her and found the clasp to her bra. I found the catch and undid it, letting it go slack. Her eyes met mine again as I slowly pulled it up and off her head, revealing her smooth, A-cup cappucino tits that I had wanted to touch for ages – and their small chocolate-colored nipples, stiff and playful.

I let my hands slide up along and over them, taking one nipple in between my fingers in each hand. Emily's boobs weren't great big sex-globes like Nadine's, but they were hers, and they felt great. I already could sense my future attraction to the unique kind of feminine beauty present in a small pair of breasts, on an equally petite and slender body - yet one nobody, certainly not me, would mistake for that of a child.

She slowly stood up, turned, and then before I knew it our lips met, and we began to kiss in a way that brothers and sisters just didn't in that day and age. My hands slid down to near her ass, finding the band of her panties – and together, we divested her of even those. She stood in front of me nude, and then seemed to realize she was naked; she looked at me and bit her lip.

Gone was the furious and overbearing elder sister of a few minutes ago. Now she looked vulnerable and quite smaller than me, and she had folded her arms over her small breasts – like she was afraid of me seeing them. I took her hands in mine, pulling her close and admiring her slim, well-shaped body. I realized I needed to put even more effort into working out if I was going to feel at all adequate next to such a beautiful woman. I pulled her arms behind my back, then let go and closed my own hands behind hers; it drew us together tightly, pressing my dick against her stomach and her breasts to my chest.

She was so slender, and her skin so soft, that I didn't want to let go. I kissed her on the head and ran my hands up and down her bare skin, teasing the sides of her small breasts. I sat down on the bed again, and pulled her close again and then sucked one of her nipples into my mouth. I could feel her quickening breath in my arms, and knew instantly that she had sensitive breasts. I could have sucked on those little tits all day if my cock wasn't raging at me to fuck her. I also felt her trembling a little – and I remembered, she was one of those people who got cold much too easily.

"Are you cold?"

"Um, kind of." She sounded a little sheepish, and still vulnerable – looking to me to take charge. So, I realized, as tough as she was, in bed she wanted the kind of man who would just be a man. That suited me fine.

I led her onto the bed and under the covers, and simply held her for a while. She had to be noticing my erection pressing against her – my pre-come was smearing against the skin of her lower body, leaving trails of gooey stuff all over her stomach. After a while, her passive attitude began to fall away, and she started to return my kisses and turned towards me in my grip. I'd never noticed how much more slender she was than me. I felt so powerful, so mighty, so dominant.

My sister had seemed for so long to be the one who knew everything and always led the way – and even as we aged, and I grew bigger than her, until then I'd always seen her as the big sister and it somehow made me overlook how short and feminine she had become as I grew. Now here she was, naked in my arms and giving herself to me. I had already decided at that point that I wanted her to be changed. I rolled over so that she was under me, and planted my hands on either side of her head. She looked smaller and more submissive than ever now.

She's probably blushing - or getting mad - as you all read this; with other girls, she's a powerhouse in bed and eats weaker lovers alive, and only I apparently affect her this way. She used to get mad at me all the time if I focused too much on her when I was doing more than one girl at once, because she didn't like the other girls seeing her as weak and vulnerable as she does under the power. Sorry, Em. You'll forgive me, I know, even if it takes a little while. Every time since that we've made love it's been as tender and affectionate as that first time.

"Are you going to fuck me?" She said it quietly, while she wrapped her arms around the back of my neck.

"Do you really have to ask?" I smiled. "Yes. I'm going to fuck you."

"I'm your sister, though..." There wasn't a real objection in her voice.

"And I'm your brother... what about it? I'm still going to fuck you."

Her arms went up and around the back of my neck. "... Then just do it, and don't stop, okay? Even if I tell you to." She looked away again, biting her lip. "I love it that way."

I bent down and kissed her, already following her instructions. Until we both came, nothing else she would say mattered now; she would become the object of my passion. I searched my thoughts, rifling through the endless memories of sex as a woman that the Experimenter had given me.

As tempting as it was to engage in a half-hour of foreplay, I didn't have that much self-control back then. All I could manage was to find one of her memories – of being fucked in this position by an experienced and tender man, and how he'd made her come with a gentle but powerful rhythm of thrusts while playing with her clit. With that in mind, and one hand under the sheets, I guided myself between her legs as she spread them.

At this point, the fact that my semen would change her into the new species was almost ancillary; I just wanted more than anything to make her mine, to do the forbidden and turn my sister into my lover. I wanted to explore this submissive side of her, to know her more deeply than I ever had, and to simply take her like this whenever I wished. I wanted our sibling relationship to turn into real love, consequences or not.

My head found her opening, and she gasped. Slowly, gently, I eased my cockhead within, staring every second at her changing expression as she was invaded. She was tight, tighter than the Experimenter had been; I knew I would have to take my time or it would hurt for her. Despite what she said, I didn't want to take this submission thing so far that she would be in actual pain.

I felt her legs wrap around my lower back and she drew me in, forcing my cock to penetrate her even when she wasn't ready. I sensed a kind of desperation in her, a need to have me inside her whether or not it hurt. She grimaced and continued, my huge meat forcing her open and sliding into her deepest places.

She clung tightly to me after I bottomed out. I simply remained there, almost suspending her in the air as I remained on all fours with my cock buried inside her. Finally her grip loosened a little, and I shifted, bringing my legs up and spreading her even wider. My hands slid under her back, all to let me hold her easier so I could begin truly fucking her. My dick was harder and readier even than it had been when I was with any of the women I had had sex with up until then.

This was special. She was my sister, and the first time we crossed into that forbidden place and made love in her hotel room is still as fresh in my mind as if it was yesterday. Nowadays, of course, it's not really forbidden. Siblings fuck all the time, it's viewed as a good way for kids to get a handle on their sexuality and feelings with less of the adequacy issues that come with learning from their mothers and father. Back then, though, that was a big no-no. You could actually go to jail for it, though under the circumstances we were in right then we were pretty unlikely to get caught.

Right around then, I remember thinking that maybe the effect of the pheromones was to make women submissive like this. Bethany had seemed to genuinely want me to come inside her mouth and the things she said had the same man-on-top feeling that Emily was giving me now; Bethany also hadn't seemed concerned at all about her own pleasure. Maybe, I thought, the effect simply made women's minds crumple and give in to anything I wanted.

I was only a few days away from finding out how incredibly wrong that was...

Affixing one hand to her waist and one over her head, I rocked my hips back and forth a little. She'd told me to simply fuck her as hard as I wanted and to disregard her own pleas, should they come. She wanted to simply be taken and fucked, for me to not control myself at all and use her body the way I wanted to – and I would do exactly that. My dick ached to be set loose, and I slid it out about halfway, then rammed it back in.

She squealed, calling out my name softly as the pole forced her back open. I knew whatever pain she felt now would quickly become pleasure. I didn't care if this whole episode was brought on my whatever artificial attraction the pheromones had put into her; if I had to, I would use the power on her again and again, just to feel this. I roughly kissed her, taking her head in one hand, and she sloppily tried to respond. I slid myself out and in a second time, then took on a steady pace. She groaned and remained still, letting me have my way with her.

Eventually she closed her eyes but stayed in the same position, her arms and legs wrapped around behind me. I wanted this to go on forever, but I knew my penis had other ideas. Already I could feel my balls boiling and I was trying my hardest to keep from exploding right there. I wanted to see her come; I couldn't go this far – capture her fascination with my power, strip her nude, and fuck the hell out of her – then deny myself the sight of her losing her eternally reserved expression to pleasure. I wanted to see that calm face of hers fall off and look at the real, beautiful, passionate person below as she let the last of her defenses crumble.

Our relationship would never be the same, even if we never did this again; this kind of closeness, as I'm sure you all know, changes the way you see people. From now on, every time I saw her, the sight of her naked beneath me would flash before my eyes, moaning every time my dick thrust into her. I could see her small boobs giving tiny jiggles every time my waist slapped against her hips and ass; had it been possible to contort myself enough to suck on them again in that position I would have..

"Unh! Ben.. Ben! It's too... unh!" She grimaced. "Slow down! It's so rough thaaaaa-!" She trailed off with a moan as my finger teased her clit. I remembered what she'd told me, to not stop even if she said to. Her mouth was simply running on its own while her body made no effort to stop me. I instead increased my pace, pumping even harder.

As much as I loved the touch of her warm, soft skin against mine, and feeling out her every curve and crevice, I was having trouble paying attention to anything other than the silky wetness my cock was exploring. This new pole the Experimenter had equipped me with was also more sensitive, and I felt like I could make out every detail of her womanhood with it. The sense of her pulse beating in the flesh surrounding me, the tiny variations in texture inside that were unique to her, her heaving chest as her passion built, all of it I could feel through my penis. My balls kept brushing onto a wet, sticky spot on the sheets below where we met, and I knew it mostly wasn't my pre-come.

She was so hot that her girl-juice was pouring out of her, sliding down past her ass onto the bed. My thrusting became rapid, pulling almost all the way out then slamming back in. The headboard was smacking against the wall in front of me, probably pissing off the people in the neighboring room. If it was occupied at all, they never called the hotel to come up and make us stop. Emily called out my name a few more times, then her cries became unintelligible – she was moaning some gibberish in my ear as I railed her, probably meaningful but mumbled too low to make sense of.

I grabbed her hand and roughly forced her to touch herself, and after a few seconds her fingers began to circle her clit in a blur – masturbating hard once I'd helped her begin. My pole continued to piston in and out. I wanted her to come before I did, and as her cries became shorter, more rapid, and louder, I almost drooled in both lust and anticipation. Her back arched and her legs tightened behind me, and I felt her whole body tense in my arms. She loosened for an instant, then tightened again.

I could barely thrust, her legs clamped me so tightly to her. Her face was the most wonderful part – her mouth was open in a silent cry, her eyes still closed, and she was making a face of incredible, agonizing pleasure. After the third pulse of her orgasm, she finally let her breath out, and the final few pulses were accompanied by long, rough moans as the last of her pleasure released itself into her.

She was still coming down as my own passion overflowed, and I couldn't hold back anymore. Seeing her come was too much. I pumped hard a few more times, groaning louder with each thrust, and felt a familiar pleasure rushing up from the base of my dick, rapidly becoming intense. I gave a long, loud moan as my balls pumped and my cock began to spurt itself inside her.

Somehow, neither of us talked about birth control; I knew, of course, from what the Experimenter had told me that, this time, there was no need to worry about pregnancy – but she wouldn't have known that. She just laid there and let me blow my load inside her; remember, the old species' females couldn't control their fertility. I might have done it anyway even if there'd been a risk she would get pregnant – once my rod had slid within her pussy, it felt inevitable that our bodies, thoughts, and feelings would merge for a while until my semen would spill out inside her.

I slowed down as my cock pumped away, savoring the intense pleasure of it. I thrust a few more times, weakly, and let my dick stop moving and rest inside her for a few moments. I opened my eyes, and she was staring up at me, studying my face as if she was just meeting someone special for the first time.

Come to think of it, I felt the same way about her. Somewhere during this whole thing, she'd taken off the band holding her ponytail in place, and her hair was spread out under her head. I'd never seen my sister like this; gloriously nude, sweaty, messy, and glowing with post-coital bliss. We kissed again, and I withdrew, eventually coming down onto the bed at her side.

I belatedly remembered then that her body was now filled with the retrovirus the Experimenter had made me able to produce, and any time now it would begin to change her inside, altering her DNA forever to make her a member of the same species I'd been forcibly made the first of.

The Experimenter had told me that this may or may not mean she would get sick, and the process could take a few days or weeks, all depending on vagaries of the girl herself, her health, and the environment around her. There was no rush, anyway. Emily cuddled up next to me. Neither of us spoke; there was no need to. There was a lot to talk about, of course – volumes – but it could all be done later. For now, both of us had just felt something we'd been longing for, and we simply wanted to enjoy our newfound closeness.

I didn't sleep, but she took a short nap. I felt her breathing change as she nestled in the crook of my arm, her head against my chest. That patch was becoming very sweaty, and so was everywhere else we were touching, but I didn't care. It was the hotel's bed anyway, we didn't have to wash the sheets. I brushed her hair away from her face, stroked her skin gently, and then simply looked out the window as I held her. She seemed utterly content, in a way I'd never seen her. She remained asleep for a little less than two hours, before she was awakened by the phone ringing.

It was the hotel, telling me my laundry was done. Interrupted by the mundane, she sat up as I spoke on the phone and arranged to have the stuff brought up. Her nipples weren't hard anymore, but she didn't try to cover her little breasts up again this time. I came up behind her, wrapping my arms around her stomach and pulling her back to my chest. My drifting hands cupped her breasts a few times. She looked out the window too.