I am a 32 year old male doctor in my own private practice, practising family medicine. I am tall with large hands and a fairly attractive guy. I have been married for 5 years and my wife is a lawyer working for a large firm. We have been happily married and our sex lives have been excellent until about a year ago, when she found out about a night night fling which a had with another doctor, whilst being out of town at a conference. We have no children, as we are both very career driven and still busy working ourselves up.
I have one sister who is 4 years younger than me and a real stunner. She got married straight after college to a very wealthy farmer and hasn't worked a day of her life. I get to see her about twice a year at family gatherings or when we go and visit them on the farm. I always compliment her on her stunning looks and the way she is looking after her body. Being a doctor I see many beautiful women every day, but my little sister is exceptional.
Two weeks ago I got a call from her, telling me that they will be attending an agricultural conference in my city the next day and that they would love to spend the evening with us and stay over if it fine with us. They were supposed to arrive early evening. Late that afternoon as I was about to finish off my administration at the practice, she hurried into my consulting rooms, complaining that she had terrible back ache. I have never treated any of my family members in my rooms before, only the odd tablet here and there at home or at a family gathering. She seemed to be in terrible pain and I told her to lie down on my examination couch, so that I could have a quick look at her.
As she laid down, I once again admired my sister great body and especially her long slim legs and rounded buttocks. I examined her back and found that she had severe muscle spasm and suggested that I will give her an injection to relieve the spasm and the pain. She agreed and asked me whether she should sit, stand or lie down. I asked her to lie down, so that she doesn't tense up her muscles, as we all do in fear of the intruding needle. My sister had a skirt on and I asked her to lower it slightly for me, so that I can inject her in her upper bum. She giggled and said that she couldn't lower the skirt and that she would have to lift it up and show me her entire ass. I laughed nervously and noticed that my palms started sweating. I wasn't sure whether it was because of the fact that it was my sister or whether I was actually getting turned on by this uncommon scenario. One thing was for sure; I was excited knowing that I was about to see her pretty ass.
The next moment she lifted her skirt and I gasped for air when I noticed that she had no panties on. She started mumbling an apology for not wearing any undies and claimed that she battled with yeast infections and that her gynaecologist suggested that she doesn't wear any underwear. My heart was beating in my throat, but I pretended it to be the most normal thing on earth. She turned on her side facing me as I started drawing up the injection. I pretended not to look, but could see a tiny patch of dark pubic hair which immediately worsened the situation, as it turned me on tremendously. All of a sudden nobody was talking. You could hear a needle fall. I started sweating and my hands were trembling. I moved to the bed and told her that she could pinch me if the injection would hurt. She immediately grabbed by leg just below my left buttock and asked me not to hurt her. I inserted the needle and she squeezed my leg, so much that it actually hurt. I could feel that she was very tense and gave the injection slowly while I put my palm on her left buttock. I could see and feel the goose bumps on her pretty ass. After what felt like ages I withdrew the needle quickly and started rubbing her ass with a piece of cotton wool with my left hand, while my right hand softly squeezed her bum.
She started relaxing as I slowly rubbed / massaged her left bum. She relaxed her grip on my leg slightly and I could feel her fingertips stroking my upper leg and bum as I continued. This really turned me on and I could feel my cock growing harder. My crotch was about an inch away from her hip bone and pelvis. I could have stopped right there but I was getting turned on big time now. My fingers were also on auto-pilot on my sister's ass as they made slight movements in all directions.
