Wife's handicapped brother.
Last Christmas, my wifes parents came to visit us for a week, along with my wifes brother Scotty. Scotty is 28 years old and is mentally challenged, or what I call a water head retard. We only have one spare befroom, so we set Scotty up on the livingroom couch to sleep. Scotty seemed overly excited to see his sister again, he ran up to her and hugged her for about five minutes, and was kissing her all over her neck and face. Her parents said that my wife and Scotty were very close growing up, she was pretty much the only friend he'd ever had. I also noticed he had a raging hard-on when she finally pushed him away.
So later that first night, we all went to bed around eleven o'clock. My wife was really horney when we went to bed, and she climbed on top of me and rode me hard for about ten minutes, then she climbed up and straddled my face with her dripping wet pussy. I sucked on her clit and brought her to a wicked hot orgasm, then she slid back down to my cock and fucked my seven inch cock like a fiending crackwhore, till she came again. I blew my load in her hot cunt, then she kissed me on the lips, said good-night, and rolled over next to me to sleep.
I must have fallen asleep immediately after we fucked. I woke up about an hour later, and my wife wasn't in bed. I figured she was in the bathroom, so I waited for her to get back because I had to piss bad. After a good fifteen minutes, she still wasn't back, so I got up and put on my shorts and headed for the bathroom down the hall. She wasn't there, so I went in and took a piss. I came out of the bathroom and decided to go to the kitchen and get a drink of water and see if my wife was there. She wasn't in the kitchen either. I poured myself a glass of water, and as I was drinking it, I heard my wife and her brother giggling in the living room, so I headed in to see what they were laughing about. As I walked into the room, I nearly shit myself. My naked wife was on top of her brother, with his cock buried in her sopping wet cunt that I had just pumped full of cum an hour earlier. I was frozen in the doorway, not sure what to do or say. They didn't see me, so I just watched for a couple of minutes. I could tell that Scotty was having the time of his life, and it became clear to me that my wife was probably the only woman he had ever fucked in his life. I knew that my wife was only doing this out of pity, and out of love for her retarded brother, so I decided to pretend like I never saw it happen. My wife fucked him every night that week, and she also gave me some of the hottest sex ever during that week. I think she felt guilty about fucking her brother, but surprisingly, I felt no jealousy or anger, probably because I felt sorry for Scotty, and I knew he was no threat to our relationship.
About two months later, I told my wife that I knew what she did with her brother. She was very embarrassed and apologetic, and started crying, but I calmed her down and told her that I understood and that it was okay. She told me all about their childhood together and how she took his virginity when he turned 18 and taught him the pleasures of sex.