I’ve fancied my girlfriend’s sister, Vicky, since the first time I met her a year or so ago. She’s very pretty and petite with a lovely body, a nice firm arse and a lovely pair of 32b pert tits. I had always imagined that she would be as good in the sack as her older sister and it turns out I wasn’t wrong. I’m a fully qualified accountant and at the end of last year Vicky was sitting part of her accountancy qualification. She was struggling with the tax section, so I agreed to help her out. She’s 25 and is still living with her mum, so I agreed to head down to her house one Saturday. Her mum had a prior commitment so it was only us in the house. When I got there we sat down and had a cup of tea and we talked through some of the problems she was having with the exam. She was obviously stressed about it, but I reassured her that it would be ok and we’d sort it out. She had taken over my girlfriend’s old room to study so we headed up to crack on. We started off talking about the bits she was having trouble with and I talked her through them and tried to explain them in a way she could understand. It seemed to be going well and I decided we should try some of the mock questions and put some of the stuff into practice. This was where she started to come unstuck and she was getting frustrated that she couldn’t get it. I was standing behind her and put my hands on her shoulders and started to massage them, trying to relax her and calm her down. I told her to take a few deep breaths and I would go and make a cup of tea while she carried on trying to answer the question. When I came back up with the tea she had got herself all worked up again and this time she was crying and was saying that she was going to fail. I pulled her up and gave her a hug, rubbing her back and stroking her hair while trying to reassure her that she was going to be fine. I was trying to stop her crying so I gave her a kiss on the cheek and I held her head while I looked her in the eye and told her it would be ok. I brushed away the tears with my thumbs, told her I’d make sure she was fine and went to give her another kiss on the cheek, but this time she turned her head and my lips met hers. I pulled away and apologised, even though I wasn’t sorry, but I could see in her eyes she was feeling the same as me. I leant in again and this time we kissed properly, our tongues intertwined in each other mouths. I ran my hands up the back of her t-shirt, feeling her soft skin and then down over her gorgeous arse, squeezing and massaging it. I pulled her t-shirt over her head and she started to unbutton my shirt and ran her fingers through the hair on my chest. We fell onto the bed and we quickly had our jeans off and I got to admire her gorgeous body in just her skimpy thong and bra. I was rock hard and I ran my hand down between her legs, pressing firmly over her pubic mound which made her moan and also alerted me to how wet she was. I unhooked her bra and started to suck and bite her stiff nipples while I slid my hand inside her thong and started to finger her sopping wet pussy. She was bucking on my fingers as I fucked her and then she grabbed my hand and pulled it away saying ‘I don’t want to cum yet, I want to do that on your cock.’ At this point she pulled my boxers down and my cock sprang out. It was soaked with precum and she started licking it off whilst looking me directly in the eye before sinking her warm, wet mouth over the helmet and down the shaft. She certainly knew how to suck cock and I was soon thrusting in and out of her mouth encouraging her to take as much of my cock as possible. She licked up and down my shaft and sucked on my swollen balls whilst wanking off my wet cock. I couldn’t wait any longer so I grabbed her, flipped her over on her back and got on top of her, sliding my cock inch by inch into her tight, dripping pussy until I was buried deep inside her. Each thrust was making her moan as I pinned her arms down and drove my cock deep and hard inside her. I put her legs over my shoulders and fucked her even harder. ‘God that’s fucking deep, fuck me hard’ she said. I didn’t want to disappoint so started to hammer away and she started screaming. I looked down at her face and her eyes were half closed and I knew she was close to cumming. I started talking dirty to her, saying ‘You like my hard cock in your pussy, you going to cum all over my cock?’ ‘I fucking love your cock, I’m so close to cumming please don’t stop fucking me!’ I kept on slamming into her and then suddenly, amongst the screams, she said ‘I’m going to cum!’ I felt her pussy contract hard as she convulsed underneath me and I felt her warm, sticky pussy juice flood over my balls. I pulled out of her and flipped her onto her front and slowly slid my cock into her from behind and began to firmly, but gently thrust into her. Her orgasm had hit her hard, but she began to respond, pushing back against me and let out little moans as my cock started to build her up again. I began to fuck her harder, pinning her hands down again and loving the fact that I was dominating her. I then decided that I wanted a bit of domination and rolled onto my back telling her to get on top. She quickly straddled me and slid all the way down my cock and started to buck on top of me. I could feel the walls of her pussy massaging my helmet and it felt fucking fantastic. She knew what she was doing to me and she enjoyed watching me writhe with pleasure as I ran my hands over her firm tits and watched them bounce up and down as she fucked me. I pulled her down so she was lying on top of me and I kissed her as I ran my hands over her back and lovely arse and started to slam into her from underneath. This got her going again and she was moaning and screaming into the crook of my neck as I fucked her hard. ‘Don’t stop’ she said, ‘you’re going to make me cum!’ I could feel my own orgasm building and thrust hard into her until she said ‘Oh god, I’m going to cum again!!’ and I felt her pussy clamp down on my cock. This sent me over the edge and I came hard, shooting my cum deep inside her as her convulsing pussy milked my swollen balls. She collapsed on top of me, both of us covered in sweat as I ran my hands over her body and kissed her. She rolled off me and we were both quiet as the post-orgasmic reality of what we’d just done hit us. I told her not to worry and that it would be fine and just between us and gave her a hug. She seemed ok and we both got dressed and I made my way back to the train station. There hasn’t been a repeat, but I’m hoping that was just the first of more to come.