Anatomy Lesson

by Losgud

Caution: This Erotica Sex Story contains strong sexual content, including Ma/Fa, mt/ft, Consensual, Cheating, Incest, Brother, Sister, First, .

Desc: Erotica Sex Story: Boy starts getting lucky with his girlfriend, and is thus observed. So boy starts getting doubly lucky, with his older sister. They of course both grow up and go on to have separate lives. But still they intersect. As always, enjoy! My apologies of course in the endnote.

It still felt like summer, but school was back in. So, being a Saturday, the day was again special. What could be more special than the weekend?

Not long after lunch, Mom and Dad left to spend the lovely afternoon golfing with the Petersons. Not long after that, a horn was honking like girl power out front of the house. My older sister, Megan, had already explained all that to Mom and Dad over lunch. She was going out with Tiffany and Heather, hitting the Mall, and then a movie, and then really count her out for dinner. Maybe they'd see another movie after that. If she was getting close to midnight curfew, she'd call.

Once I heard the squealing girls squealing away, I picked up the phone. I called Lizzy's house. Every time I called, I'd be afraid about who I'd have to talk to first. Her dad scared me, but at least he didn't like to waste his time. After about twenty seconds of grilling me, he would either hand me over to Lizzy, or just hang up. Her mom was freaky at the other end of the scale. She'd engage me in conversations that could go on for twenty minutes. On several occasions, I was the one to politely end the phone call. Sometimes I got rewarded with Lizzy's eventual voice. Other times, it became obvious that she could chat all day, determined to not let me talk to her daughter. This time, thank god, the line picked up in one ring, and it was Lizzy. Like she was waiting for me.

"Hello?" I inquired most politely, "This is Ben. I'm calling for Lizzy, if she's available."

"Hi, Ben," she oozed.

"Hey Lizzy, what's up?"

"Just sitting here at home annoyed by my family. So good to hear your voice. What's going on with you?"

"Same as you. I'm just sitting at home. Except all my annoying family went away guaranteed all afternoon."

"Really?"

"Yea..."

"And... ?" she whispered.

"I'm all by myself and sort of bored. I was wondering if maybe you'd like to come over and study with me."

Lizzy gave her cute little giggle that just set my hair on end, in anticipation. "So what subject should we concentrate on?"

"I definitely want to learn more about Anatomy."

"Really? Hmm, that could be most interesting. Lemme ask my mom, and I'll call you right back."

The phone rang back within minutes. I picked it up about to say something naughty, when her mom said, "Hello Ben, may I please speak to one of your parents?"

I about fainted. But then I just started lying. "Mom's at the supermarket because she forgot something for dinner. Dad's out mowing the lawn. May I take a message?"

I heard her give a good sigh. I was a very polite boy. She went on a different tack. "Lizzy tells me you invited her over to study?"

"Yes, ma'am."

"But it's a beautiful Saturday afternoon! And I'm wondering why you two want to huddle inside and study?"

"You're telling me! But this Biology course we're taking is really hard. We're in this subsection now on anatomy. We've learned that the body has hundreds of bones, and muscle groups, and they all have Latin names, and for the section final we have to memorize them all."

"Oh, ick," she said. "Lizzy will be over soon to help. Just make sure you help her back."

"As always," I announced.

Our secret was that we'd been having sex for several months. I'd just turned fifteen while Lizzy was finishing up fourteen. We were both virgins until the first time. It happened almost by accident; neither of us was expecting it. We just got left alone for several unanticipated hours. The last time that'd happened was the best. I got Lizzy to lift up her shirt and let me play with her pretty little boobies.

"I know they're small and all," she whispered, "but they like to be touched. But nobody other than me has ever touched them before."

"It doesn't matter how big they are; all that matters is how beautiful they are." I was a boy, but I was a smart boy. And I was just speaking the truth. As I touched her, as I dared to suck on her ... until a car pulled in the drive and Lizzy yanked her shirt down and pulled away down the sofa as we pretended to be watching t.v. I had to talk seriously to her parents while sitting funny to hide the effect their daughter had on me. Her mom stared and searched my eyes, making me get even harder in my discreet positioning.

I had to stay awhile to let my presence be lessened. Her mom fetched me a soda, and I stayed through that, trying to kill my hard-on enough to stand up and go home. Stand up in front her parents, her oddly eyeing mother.

Finally I was let loose back home. I endured the gauntlet of my parents, and then, thank god, my big sister Megan wasn't home to toss in her own barbs. She was out on a date or something, keeping our parents up late. I left them at their watch, seated in the livingroom. I brushed teeth and went to bed relatively early for me.

My thoughts were that there was no one in the bedroom wing of the house to hear, making it safe for me to jack-off like crazy. I kept focusing on the visual of Lizzy's tits. But then her mom's eyes looking at me kept creeping in. I kept imagining Lizzy giving me blow-jobs, while it would be her mother's fingers tickling my balls that made me launch. I rested a bit, nearly falling asleep, but then started jacking-off again.

For some reason I was thinking of my sister. Probably because of the thrill of knowing that if Megan knew, she would kill me. The sound of voices and several bedroom doors being closed delayed me, but then I finished again, oh so quietly. But quite copiously!

Left alone again at a later date, we began a repeat, on the very couch, but then Lizzy shrugged away and stood up. I was startled, but then she yanked down at my hand. "I want my first time to be in my own bed." I stood up, rising to my feet because my cock was pointed down in my pants and was pushing me up from the sofa.

Nature's lift, it's called.

I thought to just follow Lizzy to her room, but then I thought better to move up beside her, slip an arm slung low around her waist. "Are you sure?"

Lizzy stopped us, mid-hall, turning to kiss me like crazy. Like an alien trying to eat me from the inside out. That sensation was sexier than expected. "I've never been more certain of anything in all my life."

As we moved into her room, I got over being scared. Lizzy turned down her bed and then faced me. "Let's just get naked and fall into bed and roll around like two naked virgins, and see what happens next?"

I quickly decided I liked a practical gal!

After the rolling around part, we skipped the other appetizers and went straight to dessert. I'd barely gotten to slide my fingers between her slippery lips down there when she reached around under her mattress and pulled out a condom.

We really didn't know what we were doing, other than her thinking of protection. We made my penetration so slow and gentle. We both gasped at the initial sensations. It was like discovering the best secret in the whole world. But quickly that approach encountered a barrier. No matter how horny I was, I didn't want to hurt Lizzy.

She noted my hesitation. "I'll be brave, I promise. Ben, I want you to be the one."

I lathered her with kisses, distracting her playing with her boobs, and then I pierced her without warning. She screamed some bad screams, and then I collapsed, crying and apologizing. I didn't want to hurt Lizzy.

I lay there in her arms feeling so crummy and almost evil. I was still inside her, but shrinking. Until her insides suddenly gave me a squeeze. I was confused, until it happened again twice fast like code, deciphered by Lizzy's giggle.

"It really hurt at first, but now, hmm-mm, it feels really good." Lizzy began moving beneath me, enjoying what we were doing. "Ben," she glittered, "we're finally fucking. Ten minutes ago we were virgins. And now we've become lovers."

Despite the rubber numbing I was so fast to blasting. Lizzy sensed that too. "Go on," she urged, "just give it to me."

The only surprise was that when I started doing precisely that, Lizzy started screaming some good screams.

Afterwards we melted onto our sides, face to face. I was feeling drowsy while Lizzy was all alive. It was like she'd siphoned off my energy. She kept giving my tired face little nibbling bunny kisses. "I didn't expect that to happen," she whispered all giddy in my ear, "not the first time."

I kept trying to doze a little but she kept squirming, until she bounced out of the bed announcing she had to go pee. But first she leaned down beside me and delicately picked up the spent condom to flush away as well.

When she returned, she crawled back into the bed and sort of clambered on top of me, draping me like a quilt. But one with a chin up and chirping, "Hope you don't mind, but now I'm totally in love with you."

"Lizzy is my girl," I sputtered, trying to rein in the typical guy reaction.

Lizzy gave me a coy look. "I didn't know what to expect. That was the only condom I have." She tossed her head, her beautiful head of hair. "So maybe it's time for me to start learning about blow-jobs, right?"

Well, one guess how that went. I had two tepid suck-offs under my belt, and was shocked how Lizzy dove right in, loving blow-jobs almost as much as me. She didn't really know what she was doing, but boy was she enthusiastic. And an intuitive learner. It didn't take her very long to have me exploding in her mouth.

She curled up against me and kissed me with her spermy breath. "I hope I did okay," she said in a hush.

I held her tight, never wanting to let her go. "I guess you didn't hear the applause, 'cause you swallowed it all." She giggled into the crook of my neck. I could state it honestly, "God, Lizzy, that was so amazing. That was the best blow-job of my life."

"Really?"

"Really!"

"Good," she grinned up at me. "Because I love doing special things for you."

After that, Lizzy wanted it again just as much as I did. Though we didn't get nearly enough opportunities, so I stock-piled condoms. And now, we had a semi-sanctioned afternoon alone ahead of us.

Lizzy was so cute, showing up with her books. Her books clasped such that they pushed up her boobs. I opened the door, stepping aside to hold it open, letting her sweep inside in all her majesty.

Lizzy looked so cute I just wanted to knock the books right out of her arms. I wanted her arms holding me. She'd passed inspection in being allowed to go over to a boy's house dressed like that. Her modest cut-offs made her butt look even nicer. Her shirt was drapery, and so lacy I just wanted to pull it up and off.

I was having all these naughty thoughts while she walked into the livingroom. I expected her to drop the books on the coffee table, then swing around to sit on the couch. Patting the place right beside her. I was already getting hard remembering how the last time I'd sat down where she'd patted on the very couch had ended:

"Do you have one?" she desperately asked.

"I have a whole box. But they're in my room."

Lizzy yanked at me. "Then let's go get in your room."

She tried to lead me, but then I wound up yanking her.

This time, though, she left me holding the door. She breezed through the room and took her books up the hallway, no doubt to my room. Lizzy left me with no doubt, winking at me over her shoulder as she started down the hall. Giving her butt some added swing.

I shut the damn front door and followed. I barged in my room after her. Lizzy set her stack of books on my desk, then pulled off her shirt with a light laugh, flinging it at me. Then she did a slow strip out of her shorts, no panties below. "Time for the anatomy lesson!" She turned the glee into a pout. "How do you expect me to learn anything about anatomy when you still have your pants on?"

Because I was stunned or something by the sight of her I sputtered to her. Recovered, I certainly dropped my drawers. I sure joined Lizzy in getting naked. We were both giggling as we thought about what was going to happen next. The hard but soft head of my cock was tapping lightly at her swollen gates.

We stopped for the condom, Lizzy rolling it lovingly down me. And then I took her, slowly, as I'd learned was best for her. Hell, it was best for me, too. I wanted to stay inside Lizzy as long as possible. Because it felt that good, even with a rubber.

We had a long afternoon at our disposal, to do whatever we wanted to do. One guess what that was. Lizzy was riding me, well into the second rubber. We were both getting close to it when I heard a noise. I dismissed it. Like a little door got shut by a breeze. I had Lizzy grinding down hard against me, so I was brushing off external stimuli.

But then I saw Megan standing looking in the small sway of the opened door. It was like a ghost story as the door was pushed silently further open. Except there my sister continued standing, flesh and blood, smirking at me.

While riding herself to heaven, Lizzy noticed my distraction. I in turn had to distract her. I didn't want her noticing my sister and scrambling off me. Not when I was that close; not when we were both that close. My hands moved from hips, sweeping down to squeeze the sides of her ass, forcing her faster.

She cried out like a wounded bird as I shot another load. Lizzy stiffened and stuttered, then melted down against me. Against me, too, a puddle. The sweep of her hair covered my vision.

When next I got a clear view of the doorway, Megan was obviously gone like a ghost. Lizzy and I cleaned up without her ever suspecting my sister was home. That part wound up working out perfect. However ad-libbed.

I woke up the next morning with my stomach turned like a pretzel. I knew there was no ghost. All I could do was wait for my sister to strike.

I awaited the repercussions, for days. Megan kept slapping me with those looks, but she never ratted me out over dinner or anything. She was just my big sister fucking with me.

The following Saturday Mom and Dad were going out to a function, one where they'd be stumbling home at two in the morning. I was really excited about inviting Lizzy over to study for awhile, but then stupid Megan wound up without a date or plans herself. At home the whole night. I thought maybe we could still sneak something, but then Lizzy bowed out. She was scared of my sister for reasons I didn't understand.

I kept wishing that the phone would ring, and suddenly Megan would be scrambling to go out with some friends. Instead she picked up the phone, and called in a pizza.

It arrived, and we slowly ate on it while watching crappy t.v. We stretched it out like a ten-course meal, but then it came time to put the box of extra slices in the fridge for lunch. I made that move, and Megan joined me standing. She went off down the hall, and soon enough I heard the shower running.

I figured she was wrapping it up for the day. I was wondering if it was too late to call Lizzy. Maybe sneak out and meet in some bushes. I did the quick kitchen clean-up, then was back on the couch, thinking about whether to phone Lizzy's house, or perhaps instead toss pebbles at her bedroom window.

Megan finished her shower--I could hear that. And her tromp down the hall to her room. Waiting for her to settle, it probably was getting too late to cold-call Lizzy's house. But the hours of lovers tossing pebbles at their beloveds' panes never ended, never going out of season.

I was a guy, like a spy, hovering like a fly and just waiting. I was ready for a couple more hours alone watching crappy t.v. before turning to bed.

I was ready for everything possible, except Megan coming back in the room, in a slight shirt that barely gripped her hips. It was a very girly t-shirt--the front showed a little kitty curled up asleep in a bed of roses.

Megan slid in and stood right in front of me. Her shirt hem was just low enough I couldn't guess about the panties.

"Want some more pussy?" she giggled, hiking the hem. There were no panties, and there wasn't any hair. She could tell I was astonished. "Your little girlfriend still has her little bush. But not me."

I blinked and my sister had my cock out. And then she had my pants shoved down past my knees.

"W-w-why?" I stuttered.

Megan shrugged. "I watched, and it was so hot. You fucked her so good, and knew what you were doing."

"I," my voice broke, "I ... I just learned it made more sense to slow it down." And that was the truth. I'd figured it out with Lizzy. I liked to make her like things I liked. It felt so good, why not linger and truly enjoy it?"

"Exactly," my sister answered. "And now I want some of the same." She reached down and seized the root of me, steadying me as she poked around then lowered herself down on me. Her hand went away as she sank me fully inside her. Thrust me fully inside her, really. Okay, she fully impaled herself upon me.

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Story tagged with:
Ma/Fa / mt/ft / Consensual / Cheating / Incest / Brother / Sister / First /