[As before, everyone here is 18, and whether it is real or not, is up to you to decide. I won't deny it, but I won't admit it either, since I have no desire to get into trouble.]
It wasn't long after finally seducing my parents, that I found out for sure about the affair between my brother, David, and my Mom. I had finally gotten into my Dad and Mom's bed, and the freedom to be as sexy as I wanted was a powerful aphrodisiac for all of us. Dad and I were constant sexual partners in the evenings, and with Mom off work for the summer, it was almost always a time for some kind of play. I certainly stopped worrying about wandering around the house in a lot of clothes, and I hadn't worn a bra in weeks. So, when the phone rang I didn't think much about it.
It was my brother, who was doing what he does on almost a monthly basis, and that is call Mom to get a favor. He is in the Army Reserves, and sure as the world was turning, right before drill he was calling to get his "free" haircut. This was a normal ritual, which happened usually a day or two before he had to show up for his military duty. The haircut itself, ever since we were kids was usually done outside on our rather secluded back deck. This made sense because the deck was perfect to accommodate the cleanup from all the hair flying around.
Mom warned me, to "dress appropriately" and that David had no idea about what we were doing together. I was admonished to be on my best "behavior" around him. Clearly, the last thing she wanted was for David to know that I was "doing" Mom and Dad on a daily basis. He also didn't need to know that I had all but moved into the bed with Mom and Dad, and that the only thing I was using my bedroom for was to store my clothes.
Forced into some sort of a basic modesty, I opted to change from my skimpy bikini bottoms to a sleeveless sundress, specifically one that did not require a bra. I then waited until Dad came home, so I could immediately flash him my quite naked ass. Just because I had to wear a sundress didn't mean I had to wear underwear, so I didn't bother with it. Instead, I was waiting on Dad as always to show him that his "baby girl" had been waiting on him all day with a serious case of the "hornies." When Dad came in, I immediately gave him a huge hug and deep kiss, while placing his hand on my quite naked ass. We were in this position when Mom found us as she walked into the room.
Not impressed that I was still playing games with "company" about to show up, she walked by and smacked my bare ass very hard! Looking at both of us, she advised Dad that David would be home shortly, and that we were to "Knock that crap off!" Not happily, with my ass still stinging, we broke the "clinch" and started to get ready for dinner.
Like a precise watch, David showed up on the doorstep just before dinner. This is part of what he does, since in addition to a free haircut, he was scrounging a free meal. We sat down, ate, and then we all headed our separate ways. I watched Mom, strip down to just her panties, while David got down to his boxers. This too was pretty standard, since when the hair started to fly, it made clean up a lot easier the less you had on. Believe it or not, all of us got haircuts this way, and during the summer months, being out on the back deck half naked was taken for granted.
Suspecting, or at least hoping, that there might be more happening, I decided to take a different track. Especially since I had somewhat suspected that Mom and David weren't exactly "strangers," I did what every horny little sister does when she is curious. I spied on them. Making sure Dad went into his home office to take care of some work, I ducked into Mom's sewing room, which has a pretty good view of the back deck.
I crawled over the couch, and got comfortable, leaning over the back and staring out the window. At first, it looked to me like the standard haircut. Mom was cutting his hair, and moving around him trimming him up with the clippers, as he sat patiently getting his "ears lowered" as Dad calls it. I almost didn't pick up on it at first, but then I noticed that one of David's hands was on Mom's waist. Then to get to something around his ears, she almost straddled his right leg, and he lifted his knee up to where his thigh was now lodged between Mom's legs. Her grinding was barely perceptible from where I was perched, but that didn't last for long.
All at once, I noticed her arms drop to her sides, still holding the clippers, and her grind became a little more obvious. Finally, she just dropped the comb and tossed the clippers to the side, and as I watched, David was obviously leaning in and sucking on her titties. As he moved back and forth between them, Mom was now openly grinding on his leg.
