Sister wanted it so bad

I (23) live at home with my parents and the younger of my two sisters, my other sister is the oldest and is married and has 2 children. I'm not a lady's man and rarely even get a date and have paid for every fuck I've had. Till Last April that was, but my younger sister 20 wanted so much to buy new shoes and go see her favorite artist in concert. Not able to afford either, she decided to ask me for a loan. Our parents wouldn't loan her that amount for such things, so she didn't ask them. She did work a low paid job and would never be able to pay me back, unless she won the lottery. I'm a mechanic and work at a car dealership where I learnt my trade and I do repairs on the weekends for extra cash on the side. Not dating and rarely hiring hookers also, I had quite a bit put aside. My sister is pretty and has a great figure like most her age, but not a standout beauty in a group of girls her age. I'm skinny and nothing special in looks, my sister likes to tease me by wearing very revealing clothes around me when we're alone at home together. But having just teased me the week before, she knew a loan would be very hard to get off me. She was and is sexually active with her boyfriends, but they come and go regularly. Having caused me to get an erection the previous week, she thought maybe she could use it to her advantage. But couldn't come up with a way to use it against me, watching return home and nearly walking into a tree while I watched a good-looking girl walking across the street. Gave her the idea of stripping off naked for me to look at her, but it didn't seem enough for money she needed. Showering with me was her next idea, but she still might need to do more. Fucking me was her final option and it had the advantage of being quick and more likely to be successful. Her first and only chance was the upcoming weekend our parents would be away visiting our sister. So, she decided to fuck me for the loan, but she knew it wouldn't be paid back by her as she never repaid any loans she had gotten from our parents, why would I be any different. She approached me on the Thursday evening our parents were out at the time and due back anytime. She was straight to the point with her offer, I was shocked and didn't answer straight away. Finally, I said I needed to think it over more as our parents drove into the driveway. Friday I couldn't get her offer out of my mind and every time I thought about it, I got a hard-on. So, I decided to accept her offer, I gave her the okay sign on getting home from work. She smiled; our parents left next morning, and I went to work as did my sister. She was home at 3 and I got home at 4. I asked her how she wanted to proceed and as she thought I was still a virgin she decided to shower with me first and take from there. Suits me I answered and as we showered, I got a hard-on, and she said it was the biggest she'd seen. I thought she was building me up, but after the shower we when to our parent's bed and had our first fuck. I was awkward at first but followed her instructions and improved. Then we had our dinner and after she wanted to try it again and so back to our parent's bed. In all I fucked her three time before we slept together and, in the morning, she fucked me again. Then she asked for her loan, and I didn't see her again till after our parents got home around 3 in the afternoon. I was very happy with our deal and thought I would do again if she ever asked me again. Well, she had thought I was the biggest cock she had ever seen and that was the main reason she fucked me 4 times. I found that out in late May, she came home from a failed date and our parents were away again (same reason). She was horny and she liked my big cock enough to fuck me again, just twice that time, but no charge. In July she had finally broken up with that boyfriend and I became her living dildo you could say till she got another boyfriend. But she had trained me well and I had more confidence and with my sister assistance I got a date with a workmate of hers. One date became two and on our four date we became lovers. It helped that her workmates car was old and needed a lot of work done. Having a mechanic boyfriend was perfect arrangement and still is as we're still dating. No more sex with my sister since early august when she got her current boyfriend. But she taught me well and my girlfriend enjoys the results of my sister's training.