This is a true story even though it happened quite a few years ago now.
My parents were going away on a 6 week cruise I was 18 at the time and they didn’t want me to miss school so they asked my older sister to move back home to look after me while they were away. My sister is fifteen years older than me and wasn’t impressed as she had her own apartment and a job in a very fancy restaurant and liked to party after work and didn’t usually get home till 2 or 3 in the morning, but she agreed as long as it didn’t interfere with her life.
My parents left on the Sunday and for the next 4 days my sister and I got used to sharing the same house, she made a big effort didn’t stay late after work and we got on great, on the Friday I got off school early and came home, when I walked in I could hear my sister in the shower getting ready for work that night, so I just went to my room and changed and waited for her to finish her shower before saying hi, in hind sight I should have warned her I was home early as when I heard her come out of the bathroom I stuck my head out of my room to say hi and she was walking through the house naked except for a towel on her head, she screamed and bolted for her room slamming the door behind her, I felt somewhat embarrassed as this was the first time I had ever seen her naked but it also gave me a major hard on, I sat on my bed and all I could picture in my head was my 5ft 2 sister and her hot body, I guess about 30 minutes past and she called me to come to the living room when I went out she was dressed and ready for work but felt the need to lecture me about respecting her space, I have always been tall for my age I was 6ft 1 so you can imagine my smaller sister looking up at me trying to tell me off,  I couldn’t help but laugh then she saw the funny picture and joined in so after talking for a little things ended up ok between us and she went off to work.
I got woken up around 3.30am by the front door slamming I got up to find her and her boyfriend totally drunk sitting at the table having another drink, after her lecture on respecting space I went back to bed and left them alone, I was almost asleep again when I could hear them start to argue, I could hear him saying to her you know your horny and you want it but she was saying no my brother is here, the fight continued for a while then I heard him call her some names and the door slam,  being wide awake now I went out to see if she was ok to find her sitting at the table crying, I tried to comfort her but she had a lot to drink and nothing I said was helping so I told her to go to bed and sleep it off, she asked me to help her and to get a bucket as she was feeling sick, half carrying her I took her to her room and sat her on the bed and went to get a bucket when I got back she was laying across the bed asleep so I lifted her legs into bed put the bucket beside her and went to watch some TV as trying to sleep was now pointless, it couldn’t have been more than 5 minutes and I could hear her throwing up so I went to check on her to find her on her knees head in bucket when I asked if I could do anything he said no leave her she would be fine.
A short while later I heard her moaning thinking she was still being sick I went back to check on her she was laying on her back in bed totally naked one arm raised across her eyes the other hand was between her open legs playing with her clit, I couldn’t believe it I got an instant hard on as I watched her, I could see her juices running from between her pussy lips I took my cock out of my shorts and started to stroke it as I watched her, now I wasn’t a virgin having had sex with a girl twice before but I had never seen a woman masturbate before let alone my sister  I  watched her body spasm in orgasm no soon did she stop she took her hand away from her pussy all I could see was her juices flowing out between her lips, I am not sure what made me do it but I reached down to touch her running my finger between her lips and through her juices when I took my finger away it was soaked I held it to my nose to smell her,  it was a sweet smell so I touched my finger to my tongue it tasted sweet so I sucked my finger all the time just looking at her naked body and open wet pussy, now I am quite well hung about 7 ½ inches and  thick but I had never had a hard on like this before, I thought my cock was going to burst it was so big, I reached my finger back down to her pussy to get some more of her juice as I slid it between her lips she pushed her hips down to meet it forcing my finger deep into her pussy, I froze I didn’t know what to do I wanted to run away but her pussy was so tight it was like it was gripping my finger inside her, before I could decide what to do she started rocking her hips back and forth on my finger so all I could do was stand there and let her it seemed like for ever but it was probably about 2 minutes before she let out a moan and started to orgasm again her hips pushed down and moved faster against my finger my cock was pulsing and I wasn’t even touching it,  she started to cry out as she came as she did she took her arm away from her eyes and looked at me saying what the fuck are you doing, I said I don’t know I am sorry and bolted for my room slamming the door behind me, I got into bed my head was swimming as to what I had done or what we had done, I was scared,  but also excited,  would she tell our parents, how was I going to face her again, I don’t know how long I lay in bed for before there was a knock on the door and my sister saying I need to come in and talk to you I told her it was open, she came in wearing one of my tee shirts she looked so hot I could feel myself getting hard again she sat on the edge of the bed not looking at me and started to explain how what just happened was wrong and it was her fault for drinking so much and that I shouldn’t blame myself for touching her, I reached out and put my hand on her arm asking her to turn to face me as she did she had to lift one leg onto the bed a little and I could see up the shirt she was wearing, she still had no panties on, as I looked at her I told her how sexy she was and that she had made me hard again she looked at the blanket and could see my cock bulging saying she could tell adding she didn’t get a real good look at me before I ran out but it seemed quiet impressive which made me feel proud so I asked her if should wanted to see it properly and before she could answer I pulled back the sheets so show her my fully hard cock, her reaction was holy cow you are going to make a lot of women happy with that thing then she asked me if she could touch it, I was so turned on I said sure, she took it in her hand and started to rub it  as she did I put my hand between her legs and on her thigh she turned a little more easing back my foreskin and opening her legs as I started to move my hand to her pussy she lent over and put my cock in her mouth I stopped as she started to suck me her head going up and down on me a little deeper into her mouth each time, she stopped for a second to tell me not to stop what I was doing then went back down on me, I had my cock sucked before but never like that, I was getting my first deep throat, or should I say attempt at one, she could only take ¾ of me, all the time I was sliding my finger in her pussy, I guess she knew how good she was doing it and how close I was to Cumming because she just stopped told me to slow down and relax and close my eyes when I did I felt her stand up and take the sheets right off me…she told me to keep my eyes closed as I could feel her get back on the bed the next thing I knew she was rubbing her boobs over my chest as I felt her moving back on me I thought she was going to suck me again as she had my cock in her hand but it felt a bit different I opened my eyes to see her rubbing my cock between her pussy lips before she eased herself back onto me and right into her pussy, she put her hands on my chest sat up and started to ride me, it was incredible she was so tight she told me if I felt I was going to cum to tell her so she could stop as I wasn’t allowed to cum in her or before she did, well she rode me like that for about 5 minutes and then had an orgasm when she stopped shaking she realized I hadn’t cum when she asked my why I told her she said I couldn’t cum in her, she seemed surprised but told me I was a good boy and started to ride me again telling me this time she was going to try and get me all the way in as the first time she couldn’t as I was too big, after a few minutes she sat up and pushed down all I could see was her pubic hair against mine as she rocked her hips I could feel pressure on the head of my cock I didn’t realize it back then but I was hard up against her cervix as her riding got faster and harder I told her I was going to cum and she should stop instead she reached out and gently squeezed my balls as she reached another orgasm, so did I Cumming deep in her pussy totally filling her, she lay forward on my chest saying that was amazing, I thought to myself that’s an understatement,  she asked if she could just lay with me in her for a little bit as she put her head on my shoulder we both ended up falling asleep.
She broke up with her boyfriend the next day saying he was a lousy screw, and the sex with her while my parents were away just got better and better even if she did complain about being too sore to walk at work a lot of the time.  
That was the first time I ever had sex with my sister, she was even the first woman that swallowed me, but it wasn’t the last between her and some of her friends I was in high demand and learnt a lot I also found out how most of them were what you could call quiet kinky, years later even though my sister has been married and had 2 kids now,  we still have sex when i am in town  and because she had C-sections she still has the tightest holes and loves it when I cum deep inside her.