Before I go on I want to explain a few things. Even though I call my mom, Mom, she is actually my step mother. Dad married her when I was five and she was like a real mom to Sis and I. Our real mother left Dad when he went to work for the State Department. She was absolutely against him taking that job since he was going to different unstable countries and she absolutely did not want to leave the states. Rather than separate, they just divorced. Sis swore that he had a lover and that was behind the split. Our step mom was perfectly happy raising us while Dad was off doing his Foreign Service thing. Sis also said Mom was a real swinger and fucked half the school board, county tax assessor, and our school principal. I just couldn't believe that and figured Sis was trying to make her round heels reputation look not as bad as it was.
A week passed and I hardly saw Sis. I was in bed and asleep by the time she got home and my classes were earlier than hers and she didn't awaken until I was gone. She was a brilliant girl and qualified for a scholarship at a far off university which included her finishing her senior high school year in some advanced studies there. This happened out of the blue and she was gone two weeks after my basement blowjob.
Prior to leaving she said she would give me one more chance to do her some good as soon as Mom was out of the house. Mom was too busy with plans for Sis's trip to go anywhere. I was determined to do Sis some good and was whacking away twice a day trying to get staying power from wearing my prick out.
The day before her departure she told me to go the basement because Mom was napping. We went down there and stripped, no kissing, cuddling, or any of that lovey dovey stuff and lay on an old blanket on the cement floor. I was the consummate lover as I took my time and even fondled her tits and rubbed her firm round ass. She actually got wet and I slipped in with ease. I guess the wetness lessened the sensations as I slowly pumped her. She wrapped her legs around me and with her calves against my backside drew me into her with a force I couldn't muster. My thoughts started out on the usual disgusting things but soon all I could think about was how good my dick felt in her pussy and how good her movements made me feel. I about bit my lower lip off holding back and I alternated between fast and slow thrusts. I heard her breathing get deeper and soon she was making a soft low moaning sound. I had these marvelous feelings shooting from the tip of my dick into my ass and up my back. With each wave I felt like I would explode into her. I bit my lip as she cried out "do it do it do it Ron," and then she gave one massive thrust and cry as I let loose with my own cry of ecstasy.
Mom chose that minute to bring a laundry basket down to the washer. She set it down on the washer and went back up the stairs as Sis and I froze together not knowing what to do. We wiped ourselves off, dressed, and went up stairs. Mom just said that it's a good thing Sis is going off to school before she got pregnant by her brother. Sis said that she takes the pill; Mom said of course she knew that because she had signed off on it a year ago. She added that the pill wasn't foolproof. I was speechless. Then we all sat down and had a long talk about incest, brotherly/sisterly love, and that was it. Sis left the next day. Mom said she wanted to have a serious talk with me.