This happened a couple of years ago. I was 28, bi and was in a dom/sub relationship with a much older man. I called him Master. This guy was very controlling and wickedly sadistic. I loved it and would do anything he said. He'd do anything he liked with me including making me confess all my fantasies, anything i'd ever jerked off over etc. One day I told him I used to watch my mom get undressed when I was a teenager and we were on holiday. He got so turned on hearing the story and he would bring it up often. He got me to tell him all about her, that she was 53, divorced, that I could sometimes hear her masturbating late at night. He even had me give him a picture of her. Sometimes he would stroke my cock while he made me look at it. A couple of months later Master invited me to his place one day. He let me in and took me to the front room. I stripped naked straightaway as he had told me to do whenever I arrived there. He stood there looking at my hard cock and smiling. He said he had a confession and a surprise for me. He told me he had wanted to meet my mom after what I had told him, so he had gone to an event she was hosting. He said he was just curious but had actually ended up chatting to her. Anyway, the short version is they had flirted and hit it off and they had been hooking up occasionally since. Both of them understanding it was just sex. At this point I was pretty shocked, I didn't know what to say, I just stood there while he told me about it. At one point I remember him laughing and saying that now he knew why I was such a slut and I'd got it from her. He said she'd told him she hadn't been with anyone for years since my father left and she was loving just having a man take her again. I started to get really turned on thinking about the two of them and how he was going to tell me all about it, that maybe he had even taken some pictures or something. Then he told me of the surprise. He had been suggesting to her that he invite one of his friends over who he said would love to fuck her. She would be tied up and blindholded and the guy would come in and fuck her then leave and she'd never know who it was. He told me she had loved the idea of being used by a stranger like that. At first I didn't really register where he was going with all this. I was still thinking along the lines of maybe hearing a few stories and seeing some pictures of my mom naked and getting fucked and how that would be hot. I'd had a few peeks at her over the years but had never gotten a really good look. It started it excite me a lot that he might be about to show me. Then he suddenly pierced my fantasies with "she's upstairs right now waiting for the guy". Suddenly my heart was beating so hard I could hear it in my ears. I stood there too shocked to say or do anything. After a few seconds he took my hand and led me to the stairs. I was so used to being completely submissive with him I didn't do anything but follow him obediently. We got to his room and I was nervous as hell, I didn't know if I could do whatever it was he wanted to make me do. I hestitated and he gave me a look that said 'obey me'. He looked down at how hard I was, probably harder than i'd ever been before, and he smiled. He said "you're always such a horny slut, you'd probably fuck your mother if I told me to". Then he chuckled quietly and led me into the room. We walked into the room together and I was almost afraid to look at the bed. My eyes were on him or the floor. He took my shoulders and turned me and pushed me toward the bed. Then I saw my mother as I had never seen her before. She was as naked as I was. She was positioned on her knees at the edge of the bed, her ankles hanging over it, with her head and shoulders pressed into the matress. Her plump ass was sticking up in the air and her large breasts were bulging, compressed between her body and the bed. Her hands were tied behind her back and although she was facing us she had on a thick blindfold. Master led me around the bed so I could get a proper look. He absolutely loved it, seeing me looking at her naked body. He guided me behind her. Her legs were spread as she knelt there on the bed and I could see every detail, from her asshole down to her pussy. She was a bit hairy but I could make out everything clearly. I think he had probably been playing with her before I got there as she looked open and really wet. Master stood behind me, he reached around and started stroking my cock very gently. He whispered in my ear "now you're going to fuck her for me slut". I started to back off and shake my head, wanting to protest but not wanting her to hear my voice. He held me firmly against him, held my cock in his hand, and started to push me forward. I was powerless to stop him, he was a big guy and I was pretty skinny, and part of me didn't want to stop him. He continued guiding me until my cock was pressed against my mom's pussy. He rubbed it against her and it felt amazing, for the first time since we'd got there I heard her make a sound, a soft moan. He whispered to me again "put your cock in her". At this point all I wanted was to do as he said, I was so horny and hard as a rock. I thrust my hips forward and penetrated her easily, sliding all the way to my balls. It felt incredible. She was so wet and warm and eager. She groaned as I filled her. I just stood there like that for what seemed like ages. Master broke in "he's shy sweetheart, give him a little encouragement". I listened as my own mother started saying things I'd never believed she would say. She was moaning things like "oh you feel so big", "come on fuck me hard", then it was just "fuck me" over and over. It was an unbelieveable experience, hearing ones mom begging for cock, and not just that but unknowingly begging for her own son's cock! I just began to fuck her, I couldn't do anything else. I started slow but worked up to pounding her within a few minutes. I couldn't help myself, I just gripped her hips and drove into her. It all felt like a strange dream. I couldn't last that long. My mom was writhing and moaning, pushing back against my cock. She was horny and wild and I answered with long hard thrusts deep into her. I kept as quiet as possible, terrified even the slightest sound might tip her off as to who I was. Master could obviously tell I was getting close. He said "I think he wants to cum in you". She just moaned loudly. "Do you want that you little whore?" he asked. She laughed and said "god yes". From that point she was moaning and begging me to cum in her. She started to cum herself and I couldn't take it any longer, feeling her spasm around my cock sent me over the edge. I buried my cock deep into her and came harder than I think I ever had before. It felt like it went on forever and I must have pumped a huge load of hot cum into her. In the aftermath we were both panting like mad. After a minute or two Master came to me and pulled me back, my cock slipped out of her pussy and the last thing I saw before he took me downstairs was my thick cum dripping out of her. As she heard us leaving she even said "thank you". When we got downstairs Master was delighted. He said he had loved watching us. He told me he knew I would want it and would do as I was told. He was very pleased with me. I on the other hand was really embarrassed and humiliated, which Master also loved. He said I was a great slave and that he was really impressed that I would fuck my own mother just because he told me to and I knew it would please him. He also said he could tell I had loved it. I felt pretty ashamed. He was still horny as hell. He had me suck him off while my mom was still upstairs. Then I left. Seeing my mother later after that was odd. She clearly had no clue who she had let fuck her. I just pretended like everything was normal. Master called me a later and told me everything she had said after i'd gone. She had told him she had loved it, getting used by some stranger, and she loved how big he was and he had made her cum so hard. I started to get turned on again. I had this secret, I'd made her cum and i'd cum in her and she would never know. It happened two more times in the same kind of fashion. The next time she was on her back and while Master fucked her I knelt by her head playing with her tits and let her stroke and suck my cock. She was great at it. I came in her mouth and she swallowed eagerly. The final time I fucked her again. I made her cum after, playing with her clit while my cock and cum were inside her. After that I told Master I couldn't do it anymore. I was so paranoid about her finding out. I even wore different aftershave and deodourant than usual the second and third time. But still I knew she probably would find out eventually if we kept going. I didn't want to change the relationship I had with her outside of what had happened. Master stopped seeing her and she never found out. But I'll always remember those times when my usually sedate mom had shown she could be totally wild and uninhibited. Sometimes I feel guilty and other times I wish I hadn't chickened out and had fucked her a few more times when I had the chance. Master loves to call me "the slave so horny he would fuck his own mother" and still likes to make me cum thinking about it.