It started with me watching her through cracked doors taking showers, and any time I could get a peek at her. This led to me planning time when I woul... jack off and keep my door open. At first I thought nothing was working until one day I noticed someone leaving my door after I came. I started to get a little braver in these endeavors. One day my sister was in her room reading a book when I walked in. I jumped in bed with her and started to tease her like any other big brother would. I started. "Yes," she sighed, "we did didn't we."There was a long pause."Mum?" Yes, darling?" Did you mean what you said just now" he asked, referring to what his mother said whilst in the throes of passion. "Always wanting to have sex with me".Helen looked embarrassed, "Erm.. I didn't realise it at the time but yes I suppose I did." she said quietly."Why?" asked Mark.Her blue eyes fixed on his."I think it was because I had found my knickers with your cum on them, and found it turned me on." Oh!" said. ” I didn’t know where to look so fixed my gaze on the ground in front of me. I felt her leaning on me slightly as she placed her hand between my legs and lightly squeezed my erection. She then turned to walk away and said “ok well why didn’t say that in the first place, come to my apartment, number four, at eight fifteen this evening.” Still staring at the floor I repeated her flat number and time “number four, eight fifteen.” “Be sharp, I hate to be kept waiting”,. The sensation became intense.Suddenly my Master's cock thrust forward hard, as far as it could go into my wife's cunt. I could see the base of his cock tense and his balls began to twitch against my licking tongue. At that moment I felt my own cock begin long spurts of cum into my sister's mouth. She sucked even more earnestly, and I could feel her mouth and tongue swallowing as I filled her mouth with my cum.My orgasm just started subsiding, Sarah's mouth still swallowing against my cock,.