I was past the point of thinking twice, so I worked my shorts down and also got my shirt off. I turned to my side again, facing her back in the darkness. She move back against me and encouraged me to wrap my arms around her, and I did so cautiously. I wrapped my arms around my sister’s small waist and she put her hands on mine where they rested on her stomach. Being naked under the sheets, holding my sister, sent a tremor of nervous anticipation through me.
“Go ahead.” she whispered.
I gently began to push my penis upwards, guiding it a few inches along her butt cheeks. She held my hands a little tighter but otherwise was still. I drew myself back down and slowly pushed up again. I could feel her nightgown push deeper between her cheeks as my dick wedged into her crack. I slid myself up and down against her butt, holding her tight.
After several moments of this, I could feel our bodies growing much hotter and we were both beginning to sweat. My penis ground against her firm butt, sliding on the fabric of her nightgown. Her hands were gripping my arms tightly as we pushed together. Suddenly she began to shift and turn her body, holding my arms tight to her and forcing me to follow as she rolled onto her stomach, pulling me on top of her and sighing contentedly. She encouraged me to slide my hands to her hips, then put her arms under her head. She moaned happily as I resumed my thrusts.
Laying fully on top of my sister was a feeling I couldn’t fully grasp. The excitement, the dangerous thrill of it was so much to take in. I concentrated on my dick, nestled between her fleshy butt cheeks as I rubbed it up and down. I couldn’t believe we were like this. I couldn’t believe my sister had just pulled me on top of her. She had just given me permission to use her body as I wished and as her moans suggested, she was as excited about it as I was.
Figuring I wouldn’t get this chance again, I slowed my thrusts down and took a firmer grasp on her hips. I concentrated on sliding my penis as deep between her cheeks as I could get them through her nightgown. The sheets stuck to my back as I pulled my hips back and moved them forward to slide myself up. I heard her release a breathy gasp and she rocked her hips back a little, giving me access to as much of her butt as she could. I took the hint and worked my cock through the grove again, and again, seeing her smile in the moonlight. I reached my arms up and placed my hands on her ribs, just under her breasts where I could feel them against the edge of my hands. She moaned happily. She spread her legs a little. I wasn’t sure what to do about that, wanting to be careful. I thrust a few more times deep into her cheeks, and with each pull back, dragged the tip of my dick a little further down each time. In response, I felt her get her knees under her a little, rocking her hips back more.
We were both fully concentrating on this game now. We both felt it when her nightgown lifted higher and my dick slipped past the edge and pressed against her panties. The head of my dick was now just under the crest of her buttocks and there was no way I could get her nightgown back down without some embarrassing struggle. So I cautiously pressed forward again, and, though she seemed nervous like me, she didn’t stop me. My little sister let me press my dick between her cheeks, right against her soft panties.
I tucked my dick deep against her panties, wedging it into her crack. Each slow stroke I made against her soft body felt incredible. I closed my eyes, gripped her hips again and ground against her slowly.
I felt her moving and paused for a moment. She was reaching down to her waist and before I could figure out what she was doing, I felt her panties slide down and catch briefly on the tip of my dick before being pulled under the crest of her buttocks. Her body trembling, she then pressed her bare ass cheeks against my naked penis.
It felt like my body temperature had just doubled and I started to faintly see stars. My body reveled in the feel of her skin, her naked skin against mine. I just lay there, enthralled at the warmth I felt from her body. I started to stroke my dick against her crack and was pleased to feel it slide against her easily. In fact, it slid really easily. It only took me a moment until my dick had burrowed right between her cheeks.
She encouraged me along with a moan so I eagerly tucked my penis between her butt cheeks as I looked at her face in the moonlight. I even took the liberty of lightly touching the top of my balls against the bottom of her cheeks and really enjoyed hearing her happy groan. Her skin felt so good against mine, her cheeks were so smooth and warm.
I began to stroke my dick through her ass enthusiastically. She grunted quietly as I jammed my cock up and down through her crack. Her sweat and my precum made the channel fairly slippery and I was taking full advantage of it. In the darkness, Sara and I, brother and sister, struggled together under the bed sheets. I gripped her chest firmly and pressed my body against her lithe frame. Knowing the end was near I allowed myself to lay fully on her, breathing heavily next to her panting face.
Finally there was nothing more to do than reach down and grasp her hips tightly. I strained forward as the head of my cock throbbed with stimulation. My balls tightened and I grunted against Sara’s cheek as my hips started to buck and my body started pumping hot semen between her ass cheeks. My cum squirted a little up her back, stopped where my stomach touched and pooled between her cheeks.
As I lay on her, gasping for air, she laid beneath me, cooing and stroking my arms and rubbing her butt firmly against my pulsing dick. She kissed my cheek and encouraged me to wrap my arms around her and hold her tight.
After a few minutes I had recovered and was able to grab some tissues from the box on the stand by her bed. She quietly allowed me to clean her up, letting me run the tissue along her back and between her cheeks where my cum had pooled. It was a very tender moment between the two of us. She was in complete surrender to me, granting me this very private, very vulnerable moment with her.
Her eyes never shined brighter than they did that night in the moonlight.
I thought of them all night after grudgingly leaving her room to return to mine to sleep.