It had been like any other family vacation with my dad and step-mom, traveling south to visit my grandparents over spring break. My eldest step-sister had been allowed to stay home, so it was me (Mike), the twins Jerry and Julie, and and my younger half-brother Tim. I was a year into puberty, the twins were two years older and Tim was half my age. Grandma and Grandpa lived in a retirement community, so there weren't any other kids to play with. Their house was at the end of a cul-de-sac surrounded by ravines, making it rather secluded. The folks and grandfolks left for the afternoon to play some golf at the country club and tour the newest changes in the community. "Mike, could you do us a favor?", Julie inquired. "Sure", I responded without hesitation. She opened her purse so i could see the pack of cigarettes hiding inside. "Can you watch Tim while Jerry and I go check out that old shed in the ravine?" I didn't care to be left out, but I had no desire to try smoking, plus I liked having Julie putting her trust in me. "And please don't tell mom and dad", she pleaded and I simply answered with a nod. Jerry and Julie casually headed into the trees, leaving me alone with Tim. He didn't seem to even notice them leave as he played with his Tonka trucks. Some time had passed and I was curious what was keeping them so long. Tim noticed me slipping away and asked where I was going. I told him that the twins had gone to explore and that I was going to see what they found. I made up a story about making sure there weren't any snakes in the path so he wouldn't follow, knowing he was afraid of them. I quietly crept down the path, careful not to startle them and get beaten up. As I got close I started to hear moaning coming from inside the shed. I carefully crouched down to peak through a gap in the planks of the wall and was shocked by what I saw. Jerry was leaning against the wall with his shorts and underwear at his ankles and Julie's head bobbing upon his erection. I was frozen in place, my eyes fixed on Julie's angelic face as Jerry's penis slid between her lips. Jerry had one hand on her head and reached down to fondle her breast with the other. "Take your shirt off", he suggested and she happily complied, braking in her dick sucking just long enough to remove the garment. I held my breath in anticipation as she unhooked her bra to reveal her young pert tits. Jerry playfully sqeezed them and pinched her nipples, causing them to protrude even further. I became aware of my own erection and rubbed it through my shorts, imagining what it would be like to suckle on my dear step-sister's breasts. Julie's talented mouth was suddenly rewarded as Jerry's hips bucked and he pumped loads of cum down her throat. Julie stood up, showed him her mouth full of his cum, then swallowed and licked her lips. Jerry reached down and pulled up his underwear and shorts, fondled and sucked her tits for a few moments then kissed her passionately on the mouth. "My turn", she gleefully declared as she switched places with him and eagerly let her shorts drop to the ground. My eyes were glued to her simple cotton panties, so soaked that I could see her young untrimmed pubic hair and the slit just below it. The little pink bow on the waistband was almost poetic as it felt like Christmas morning, and I eagerly awaited the unwrapping of that amazing new play thing. Jerry dropped to his knees and licked his lips as Julie gyrated her hips while she peeled her panties off. She reached back and braced herself with the wall of the shed, then threw a leg up over his shoulder and pulled him in. Jerry caressed her ass cheeks from below as he licked her vulva up and down. Julie blissfully enjoyed the gentle caress and tongue lashing she was receiving, her head thrown back, eyes closed tight and hands fondling her breasts. Jerry decided to advance in his technique and removed his palms from Julie's rear, reaching around the leg on his shoulder to rub her clit while he inserted two fingers from his other hand into her well lubricated pussy. She looked down and smiled at him, "How's it taste, baby?", she playfully teased as she mashed her tits together and flicked her nipples. Jerry didn't say a word, he just casually pulled his fingers out and reached up to offer them to her. Julie took them in her mouth and sucked all her juice from them, then he used his saliva coated fingers to take over the stimulation of one nipple. I was still hard but had long since abandoned rubbing myself, instead I found myself with my knees locked together and sort of dancing like I had to pee. Jerry removed his hand from her breast and gave her a sharp smack on the ass. She reacted with a little shriek and then giggled as she grabbed the wall for support and threw her supporting leg over his other shoulder. Julie humped against his face as he held her in place with his hands once again on her ass. The scene burned into my memory; their eyes squeezed shut in ecstacy, her pubic hair like a curly mustache beneath his nose and those soft tits with their protruding nipples. Controlling by breath got to be too much for me and I almost fainted, falling to my knee. I became panicked, did they hear me? I quickly fled back to the house where I gave Tim an excuse about how I had to pee and rushed on to the bathroom. Once inside I quickly stripped below the waist and began frantically masturbate. Visions of Julie, my step-sister, still fresh in my mind and destined to perpetually arouse me for the rest of my life. Once my orgasm had subsided I redressed and prepared to face my immanent doom, but it never came. The twins returned from the Ravine as if nothing had happened, suggesting the shed offered nothing of interest even though they had been gone so long, and ironically enough reporting to Tim that they hadn't seen any snakes. Everything seemed normal the rest of the day, the parents and grandparents returned, we all ate dinner together and then played games before bedtime. I glanced at Julie often, imagining her naked and playfully teasing me with her nubile young body. Sometimes she caught me staring, but just smiled sweetly as I quickly averted my daze. We met outside the bathroom when we brushed our teeth before bed and she gave me a big hug. As she held me tightly I could feel that she wasn't wear a bra anymore, her nipples poking through the thin material of her top and into my chest. I was getting a boner and wasn't sure if she noticed, because afterwards we went to our separate sleeping quarters without saying a word. I woke up around two, needing to pee, so I crept to the bathroom. I must have been having a wonderful dream, because I was now struggling to aim the stream of urine from my erect penis into the toilet bowl. After my bladder was empty I decided I might as well stay and jerk off, but as I started to stroke it I heard someone try the doorknob. I quickly tucked my erection back in my underwear and tried to hide it as I opened the door. I was caught off guard by finding Julie waiting for me at the door with a mischievous smile on her face. She pushed me back into the bathroom and locked the door behind her, exciting me with her bold action. "I know you saw us", she confessed, "but don't worry... I won't tell Jerry". Wait, Jerry didn't know? Well of course he didn't hear me with his head squeezed tightly between Julie's thighs. She grabbed the back of my head and kissed me passionately, slipping her tongue in to dance with mine. For a moment I was worried we could get caught, but I realized we were also in the mudroom and she had a plan of escape, out through the garage and back in from the deck outside her room. Julie wasn't satisfied to just make out, she pulled her shirt over head and presented her breasts to me like a slice of birthday cake. I joyfully fondled them, nibbling on her nipples and pinching them between by fingers. She pulled my shirt off too and we joined in a topless embrace, caressing each other's backs as we resumed our french kiss. Julie lowered her hands to my ass and held me tight so she could grind her pussy against my very noticeable erection. I felt a little bold and slipped my hands down inside the back of her panties for an unobstructed feel of her tight little ass. Julie broke our kiss to offer a proposition, "I'll show you mine if you show me yours". I just nodded and without saying a word, we separated and let our remaining clothes drop to the floor. Seeing Julie stripped down in the shed was nothing compared to seeing her standing before me now, her pussy glistening in the light. "Oh my gosh, you're so hard!" Julie whisper shouted as she stared in amazement at my rock hard cock. She reached out and grabbed it firmly with her hand, then tugged me in to resume our kiss once more. While she jerked me with one hand, she used the other to guide mine to her waiting pussy. It was heaven, our tongues darting around each other's mouths, one of her hands stroking my cock while the other fondled my balls and me fingering her while caressing her butt. I thought I was going to explode, when Julie's head flung back, her body convulsing from the orgasm I had given her with my fingers. I was dumbfounded by what I had accomplished, a virgin who had never touched a woman there, being able to bring her off so quickly. I took the opportunity to taste her on my fingers to which she made a show of licking my precum off her palm and asking, "Do you know what a 69 is?" After I shook my head, she guided me down to the floor, laid me back and herself the opposite direction. She didn't say a word, just offered her pussy to me as she took my cock in her mouth. I understood what I was supposed to do and leaned in to lick her hot, wet lips. The scent and taste were unlike anything I had ever experienced, I couldn't get enough. I pulled Julie on top of me, holding her tight little ass in my hands as I hungrily devoured her pussy like it was big juicy peach, coating my face in her nectar. Julie humped my face as she took me all the way down her throat, her nose buried in my tight little ball sack. Neither of us was going to last long, but Julie came first, her convulsions sending a wave through my body that ended with an eruption of cum down her throat. She rolled off me and sat up, "I love you Mike" then I sat up and proudly replied, "I love you too, Julie". We smiled at each other, then leaned in and shared a long, affectionate kiss. "You know what this means, don't you?" She inquired, "from now on, we're secret lovers". She got up, grabbed her clothes and continued to smile and stare at me as she got dressed. Before she left, she knelt down and kissed me on the mouth, then grabbed my still erect penis and planted a kiss on the head. I stared at her cute little ass swaying as she left, jerking myself and imagining our future adventures together. After giving myself one last orgasm, I quickly got dressed and washed my face. I went back to bed and quickly fell back to sleep.