I'd always wondered why our parents would lock my sister's door at night, I'd asked once or twice in the past but was told to mind my business by her and parents would get cagey and avoid the subject. Emma was four years older than me, we got on okay, had the occasional fight as siblings do but I stayed out of her way as much as I could. When I started to notice girls 'that way' I of course was fascinated by her and when I hit 18 I did my best to spy on her in the shower or jerk off to the sound of her masturbating in the next room. I didn't care that she was my sister, she was hot! She'd usually always catch me trying to perv her though, I'd get a punch in the arm or chest, called a pervert and she'd not talk to me for a few days.
One summer, everything changed.
"I don't care Emma, you know damn fine the medication doesn't work. She can come round for a few hours and your Dad will drive her home afterwards," said Mom, I'd came home to a fight.
"I feel like I'm a fucking prisoner, it's not fair," replied Emma, almost in tears.
"Honey, you know we love you and you know why it has to be this way, I'm sorry. I'll talk to her Mom and explain okay?"
"Fine, sure, 23 years old and I can't have a friend stay the night for my birthday."
Emma stormed off and I got myself a drink from the kitchen, trying not to be noticed.
"You were a lot of help," said Mom.
"What do you want me to say, she's already feeling bad, me repeating the same shit you already said isn't going to help. Marcus, son, stop skulking around eavesdropping, go for a swim or something," replied Dad, I went to my room.
A few hours later Emma came to my room, she knocked and waited, learned about just walking in after she walked in on me jerking off a few weeks prior.
"Hi Em, you okay?" I asked.
"Why wouldn't I be. I need to borrow your dvd player, Lisa is coming over for a while and I managed to break mine."
"Uh, sure, you can keep it, I mostly watch my stuff on my laptop now anyways."
"Your porn you mean."
"Oh I stream that, why would I have disks?"
"Whatever perv, can I have it or you just going to talk all day?"
I unplugged and handed her my dvd player, got a 'thanks' and she left. I sat reading by the pool while Emma's friend was round, she was a bit of a bitch and Emma wouldn't stop her if she was rude to me. I sat with my parents watching tv on the couch when it got dark and must have dozed off, Dad left to take Emma's friend home and Mom dozed off too, she always woke up grumpy so I pretended to be still asleep when she woke and went to bed. She put a blanket over me before she left though. With the room being dark, Dad didn't notice me when he got home, he put his keys on the counter and just went to bed.
I dozed off again but woke up thinking I was dreaming. My shorts had been pulled down to my knees and I could feel a warm mouth round my cock, licking and sucking me as it hardened. I kept quiet but when my eyes adjusted to the dim light I couldn't believe what I saw, it was a completely naked Emma who was sucking me.
Once I was fully hard she straddled me, guided my cock to her pussy then slowly lowered herself onto my cock and began to ride me. I wasn't that confident with women. The few I had asked out said no so until that point I was a virgin and it was more wonderful being inside a warm wet pussy than I had imagined. Emma fucked me at a pretty furious pace, she rubbed her clit and I felt her tighten then she slumped forward, still shaking from her orgasm and caught her breath as she laid on my shoulder. I was close and it only took a couple of thrusts up into her and I almost blacked out I came so hard, pulsing my cum into a woman for the very first time.
I was in lust, the feeling of pleasure and afterglow Emma had given me made me want to worship her, to kiss her nipples that were pressed into my chest but she was sound asleep, my softening cock still inside her.
As I began to wonder how I'd wake her though, Mom and Dad walked into the room almost in a panic, when they seen Emma naked on top of me, our cum still dribbling from her pussy, Mom gasped, Dad just said 'Oh fuck'. I felt like a deer in headlights, I wanted the couch to just swallow me whole, the guilt of the incest I'd just committed now burning away the pleasure I'd been feeling.
"Son, help me get her up so I can get her into her bed," Said my Dad quietly.
I helped Dad get her into his arms, thankful she was petite and I pulled up my shorts once he carried her to her room. Mom told me to help her clean our mess on the couch with a damp cloth then had me sit on the chair. I couldn't look at her.
"You okay?" Said Dad when he got back.
"I... I didn't mean to, I fell asleep on the couch and it just happened, she didn't even ask me." I said, tears welling up in my eyes.
"It's my fault, I dozed off out here and forgot to lock her door. You're not in trouble Son but there's something you need to know. Emma is probably going to be pissed but you're not to blame." Said Mom.
"I just had sex with my own sister, how am I not in trouble?" I replied.
"Son, your sister has a pretty extreme form of sleepwalking. We've been to doctors, psychologists and even a hypnotist but nothing seems to work. We tried chastity devices but she hurt herself trying to pull them off so now we just lock her in her room at night, she masturbates with her toys instead and goes back to sleep. When she can get out though she'll take whatever man is here," replied Dad.
"Will she remember what happened?" I asked.
"Yes and no, she'll know she's had sex but won't remember who with. Go shower and get some sleep, we'll talk with her and tell her in the morning okay?" Said Mom.
"I uh, it was my first time." I said then left.
I took ages to get to sleep, my mind was reeling about what had happened. I'd fantasized about fucking Emma plenty of times but like the incest porn I watched, it was something wrong to get me off and I never imagined actually doing it. I woke up pretty late, almost jumped out my skin when I woke to Emma sitting on my bed.
"Holy fuck, about gave me a heart attack. How long have you been sitting there?" I said, thankful I was wearing boxers.
"Just a few minutes. You okay?" She replied quietly.
"I'm fine, just got a fright is all."
"I meant about last night."
"I haven't had time to register it fully I guess."
"Mom told me you were a virgin."
"Yea, I uh, just get really awkward around women, I can't seem to get a girlfriend."
"I'm sorry I took it that way, they told you what happens to me?"
"Yes."
"If you're not grossed out by your older sister fucking you I'll make it up to you. Losing your cherry should be enjoyable and fun, not a zoned out, sleepwalking slut just riding you until she cums then crashing out. Go brush your teeth."
I didn't ask questions, I did as she asked and got back to find her laying on my bed naked. I took a good look at her breasts, her shaven pussy and I felt my cock stir.
"I uh, I don't want you to feel you have to do this Emma."
"I know I don't sweetie but we're going to have sex if you want me. I'm going to give you an amazing blow job then you're going to explore and fuck me. Mom and Dad have gone out for a few hours too."
"And you're not upset that you've already had sex with your own brother?"
"I uh, no, it's fine."
Emma sat up and swung her legs round then pulled me closer to her, I stood nervously as she pulled my boxers down and took my cock into her mouth and started to suck me. She looked up at me with her dark brown eyes, her straight dark hair framing her pretty face and I groaned as her tongue swirled round the head of my cock as she gave me my first real blowjob. Being a little more awake than the night before I was able to enjoy it but I didn't last, I gasped as I felt my impending climax, Emma just grabbed my ass and kept sucking and looked up at me again as I began to spray my seed down her throat.
She swallowed everything I had as I struggled to stay on my feet then she smiled at me as she let my cock slide out of her mouth.
"Enjoy that little brother?" She said softly.
"Y... Yes I did."
"Well come, get up on the bed, you can suck and play with my nipples until you get hard again."
I was nervous at first, Emma led my hand to her breasts though and guided me, teaching me how to fondle and caress her amazing breasts so that we both got enjoyment. My cock was like steel a few minutes after touching her but she made me take my time. After sucking each of her nipples to hardness she told me to lay on my back. I was expecting her to ride me again but she straddled my head and lowered her pussy to my mouth. I did my best to emulate the lesbian porn I'd watched but Emma gave me pretty explicit instruction on how to do better and after a while she was just moaning in pleasure. I must have done something right, I eventually focused on her clit and in between gasps of 'don't stop' Emma's moans got louder then I was rewarded with a mouthful of her cream before she got off me and laid back on the bed as she caught her breath.
"Th... that was fucking good sweetie," she gasped.
"You taste really good," was all I could think to reply.
Emma got up on all fours and looked over her shoulder at me with a smile, I tried to hold back my eagerness but I got up and tried to just slam into her, she made me slow down though, told me to savor each thrust. I held on to her hips as my pace increased, trying to hold back my orgasm for as long as I could. When I felt her cumming, her pussy tightening round my cock as she quietly gasped 'oh fuck yes', I couldn't hold back anymore and pushed deep into her as my cock erupted. Both spent, we collapsed together on the bed as we caught our breaths.
"That was amazing," I said when I could speak.
"I agree, you do have a nice cock," replied Emma.
"Can I ask a question?"
"Of course."
"A few months ago I walked into you getting out of the shower, it really was an accident but when I didn't get out quick enough from starting at your breasts you got mad at me. From there to having sex with me is like a huge leap, you're way too cool about all this."
"I had sex with you last night, kinda changed things sweetie. I didn't know how you would handle this."
"And it doesn't bother you that you fucked your brother? We're family."
"You having second thoughts? You're not my first you know."
"First, what do you mean."
"Nothing, shit, sorry I shouldn't have said anything."
"Tell me, please."
"Oooh, you're one of them. Post sex guilt," she said, gently grabbing my balls. "Fine, I'll tell you. A few years ago when this surfaced, Mom and Dad had fell asleep on the couch and he didn't wake up until I was guiding him inside me. I had him balls deep in me before Mom could wake me up, I freaked out, had no memory of even leaving my room or anything. Few shrink visits later and they take me in for a sleep study, ended up trying to fuck one of the Doctors. Mom's still a little mad at me but I think that's more to do with Dad 'forgetting' to lock my room door 3 times last year."
"And if your door is locked you just masturbate?"
"Yea, I set up a camera and I almost tried to claw through the door first few times but then I take care of myself. Want to go again, I'll ride you nice and slow and you can play with my breasts."
"Sure we have time?"
"Yes but it doesn't matter, they know we're doing this."
"What? I... I..."
"Relax sweetie, they're totally fine with it, I have an IUD so you're not going to get me pregnant or anything."
I was exhausted by the time our parents got home, we'd showered together and I got hard again, I didn't even cum that time with my poor cock aching but I got her off. We were snuggled together on the couch when they got home. Mom smiled and started preparing dinner.
"Hey, I'm going to chat with Mom, go chill in your room for a bit," said Emma after kissing me on the cheek.
I did as she asked and fell asleep on my bed but woke up to Emma gently shaking me.
"Dinner's ready sweetie," she said with a smile.
"Okay, what's that grin for though."
"I have something to ask you after dinner, you're going to like it," she said then left my room after kissing me on the lips.
Dinner was pretty awkward, I couldn't shake the feeling like I'd been doing something wrong but Mom and Dad made light of it.
"So did your sister wear you out so much you can't talk? You're never this quiet," said Mom with a grin.
"Look at how red he's getting," laughed Dad.
"Leave him alone, this is all still new to him," said Emma.
"Alex, I want you to know, despite this being way outside what other people see as normal, your father and I are fine with you being with Emma. I would rather she's with someone we know is not going to hurt her. I know she wanted to be the one who asked you but one of the doctors we spoke to suggested wearing her out during the day so she doesn't go looking in her sleep. We'll give you both alone time but if you're willing to try, you have our blessing."
"Thanks Mom, I was going to ask him my own way," said Emma.
"This is um, I don't know how to handle this." I replied, I could feel my face burning.
"See, you've embarrassed him, Alex, you and I will talk later okay?"
Emma's persuasion came with a long blow job, I wasn't about to say no to her but I couldn't shake the feeling of sneaking around doing something I shouldn't. That night though, I was to sleep on the couch and Emma's door was going to be left unlocked, I woke up to her feeding her cock inside herself. The next morning I told her what happened.
"Well shit, I hope you had breakfast then, I'm going to wear us both out today, I'm going to ask Dad for one of his Mexican viagra," she said.
Spending the entire day having sex was pretty amazing, I even got to try anal for the first time which was pretty fun, by dinner time I was wiped though but thankfully our parents didn't try to tease me about it. We went for 3 days, having sex all day then me sleeping on the couch but I'd still wake to her getting me hard enough to fuck her again.
I found myself getting jealous of her too, I'd notice guys looking at her and wanted to tell them to look away, it got to a point that Emma noticed. She kissed me softly on the lips when she was riding me one afternoon and touched my face.
"I, Mr Alex, love you. We are sharing something most people won't or can't have but it needs to stay between our house. Guys are going to look at me, Mom said I'm practically glowing since you're keeping me so satisfied but none of them will ever have me. I am yours okay, no more mr jealous," she said with a soft smile.
"We're not allowed to have sex after this right?"
"You remembered, yes, is time for a new IUD, can't miss the appointment the amount you fill me with."
"You should get on all fours then, I want you nice and worn out if I'm not getting anything later."
"Mmm, tell me what to do, make me your naughty slut."
The next day I was sitting reading by our pool when Emma and Mom got home from her appointment, she didn't say anything, just put my book down that she took from me and pulled me by the hand to the kitchen.
"So, we have news and it may change everything, they told Mom more so she's going to explain," said Emma.
"Well, it turns out Emma's IUD had embedded itself in a way it was stimulating a nerve. During the day her walking about and doing other things stopped it being stimulated but at night when she'd roll over to sleep it was like her horny button being pressed. It was still working as birth control but when they went in to remove it she climaxed and squirted on the nurse. They said they'd never seen anything like it but the nurse was fine about it. Anyways, they gave her a shot instead and with her IUD gone her night sex monster should be gone," said Mom.
"Don't worry my little horn dog, Mom has agreed to let us carry on the way we are for as long as we want to, I see the look of horror on your face," laughed Emma.
"That's crazy," I replied, relieved I'd still get to have her.
"And, because it took it's time to be like that is why we didn't attribute it to her birth control," added Mom.
That night, after having sex all day, I was asleep on the couch for a final test, I woke up to Emma sucking my cock.
"Oh good you're awake, come to bed and fuck me little brother," she said with a grin.
"Did you sleepwalk again?"
"No, I'd usually have jumped you by now, it's 5am, I'm just horny."
Things did change at home but we still have sex whenever we want. Emma is allowed sleepovers and is even looking at her own place, something I'll hate but I'll always have the memories and skills learned from fucking one of the hottest women I know...