I was 12 when my step-sister Jessica wanted to "try stuff out". She was 13 at the time, and I had had a crush on her for a couple of years. My twin brother and I even competed for her affections when we first met her. I ended up winning.

We had been living in a house where the girls (my sister Mary (11), Jessica (13), and her sister Sabrina (10)) shared one room, and my brother and I shared another. We had just moved into a bigger house, each of the girls got their own room, while my brother and I still had to share. I guess after nine months in the same womb, separate bedrooms aren't a priority.

School was out for the summer, and my father and step-mother felt that we were old enough to look after ourselves. We had an above-ground pool set up on the patio out back. It was shallow enough that we could stand in it, and too small for any real swimming, but we were able to splash around and have fun.

I got to see the girls' developing bodies inside their swimsuits, even some little pubic hairs sneaking out of the crotch of Jessica's suit.

One of the days after we'd been out swimming, Jessica asked me to come to her room after I dried off and changed. When I got there, she locked her door.

"What's up?" I asked.

"I want to have some fun, without being interrupted." She answered.

We then spent close to half an hour talking about what (if any) sexual history we had. We practiced French kissing, I fingered her, she jerked me off. No big deal.

The next time we got together, we wanted to try actual intercourse, but we were worried about pregnancy. I reminded her about how the sperm didn't shoot out until the end when she jerked me off, so I could pull out right before that.

We got naked on her bed, spent some time kissing and touching each other; I couldn't get enough of her young teenage tits. Eventually, we got to the main event. I got between her legs and lined my cock up with her pussy. It took me a couple of tries to get lined up right, but I did get it in there. Jessica gasped with a small amount of pain when I broke her hymen.

From our previous conversations, I had learned about her clit, so I started rubbing it, while I was inside her. When she stopped feeling the pain of losing her cherry, I started to stroke in and out of her. I managed about half a dozen strokes before I had to pull out. I came all over her stomach; some even landed on her tits.

After that first time, we managed to get together a few more times. Jessica also added Mary to our fun. I was with Jessica, and Mary was sitting next to us when Jessica demonstrated how I would do to her whatever she did to me. She asked me to also hit Mary with whatever I did to her.

She started by pinching my nipple through my shirt. I responded with a good feel of both girl's boobs, and a pinch of the nipples. Jessica next squeezed my cock through my pants. I responded by squeezing the crotch of both girls' jeans. Jessica french kissed me next, and I followed orders and kissed my sister the same way. I was hard as a rock by then, pitching a visible tent.

Jessica said that the next activity required us to be naked, so we all stripped our clothes off. It was the first time I had seen Mary naked since we were really young and it was ok to bathe together. She was a very good sight: long brown hair, great skin tone, tiny little bumps where the tits would soon form, and a beautiful pussy with just a few wisps of hair on her mound. Mary got her first look at me naked in as many years, and probably her first look at an erection.

Jessica told Mary about how I can pull out before the sperm comes out, so it was safe to fuck. We then proceeded to demonstrate. With the added excitement of my sister watching us, I couldn't last as long as I had the previous times with Jessica. I soon had to pull out and jizzed all over her belly. While I rolled over to rest, Mary reached over and scooped up some of my jizz with her fingers, looked at for a second, and popped it into her mouth.

Mary then licked all of my cum off of Jessica's body, and moved down to Jessica's pussy. My eyes went wide, and my cock got hard again, as I watched Mary eat Jessica's pussy. Jessica was surprised at first, but quickly relaxed as Mary brought her closer to orgasm. After Jessica came, I wanted to hop onto Mary right away, but Jessica told me to wait a little bit.

Jessica started licking Mary's almost hairless pussy, got her right up to the edge of orgasm, then moved out of the way and told me to go ahead. I got lined up, with Jessica's helping hand, and plunged in with one thrust. Mary gasped for a second, and then came before I started thrusting. Her pussy felt like a tight glove massaging my cock. I'd never felt anything like that before. My times with Jessica were good, but not that good. I was using all of my willpower, thinking about baseball, etc, to try to keep from coming.

I held still as Mary finished her orgasm, and then began a slow in and out rhythm. A few strokes later, as I was about to cum, Mary wrapped her legs around my waist as she entered her second orgasm.

"I'm gonna cum. I need to pull out!" I told her.

"I don't care," she said. "Besides, I'm young enough that I probably won't get pregnant."

The very idea of possibly making my sister pregnant was enough to push me over the edge. I blasted one of the biggest loads of semen I've ever had into her. After I filled her with my incestuous sperm, I rolled over, and Jessica immediately slurped the mess from both of our crotches.

I was too worn out for another go, but we did have more fun later.

To be continued...