(As usual, you may want to read the first two installments before reading this one so you'll know what has transpired up to this point)
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I know, I know. I know what I said. I said it was best if I didn't have sex with my sister in-law Carolyn again. She said it was only going to be a one-time thing and at the time I agreed with her. I didn't think it would be a problem but damned if I couldn't get the thought of screwing her again out of my head. I fantasized about sleeping with Carolyn quite often. Frequently when I had sex with my wife, I imagined it was her sister's mouth and pussy I was sliding my hard cock into. At times I had to stop myself from calling out my sister in-law's name during sex. I made up my mind that I just HAD to have her again.
The hard part was that Carolyn was sticking to her guns. In the year and a half since Carolyn's baby was born, our families were together on three or four different occasions. Each time I set up an opportunity to be alone with her and I would casually broach the subject but Carolyn kept saying "no." It was made even worse by the fact that the Carolyn had reached a comfort level around me that meant she rarely wore a bra when she wasn't planning on going out and would frequently get dressed in an oversized t-shirt with only panties on underneath when we hung out in the evenings.
Our families recently got together again, this time at Carolyn and her husband's condo in California. After a long day sunning and swimming out at the pool on our second day there, we had some pizzas delivered and sat around watching TV for the rest of the night. They had blown up an air mattress in the living room and my son plopped down on it with Carolyn while my wife, Carolyn's husband, and I occupied the couch and recliner. Carolyn's little one was out early and was put to bed upstairs in his room. My wife was burned out after our day at the pool and she was off to bed fairly early. She went into the den off the entryway to sack out on the hide-a-bed that was set up for us.
Our son fell asleep shortly thereafter and I carried him to the guest bedroom. I returned to the living room and planted myself on the recliner and the three of us watched a DVD until I couldn't keep my eyes open any longer. I joined my wife on the hide-a-bed and I don't even remember my head hitting the pillow.
I awoke in the middle of the night and was badly in need of a drink of water. The room where I was sleeping was near the living room and I could see the light of the TV reflecting off the walls from the hide-a-bed. Wearing nothing but my boxers, I shuffled to the kitchen, which was between the two rooms, and poured myself a glass of ice water. As I stepped into the living room I saw an old "I Love Lucy" episode on the screen and found both Carolyn and her husband fast asleep, with him on the couch and her still on the air mattress.
I drank my water as I silently stood there for a moment and watched them sleep. Carolyn was wearing her usual t-shirt and panties and was sleeping on her side, facing toward the couch, away from me. Her shirt had ridden up and I was getting a good look at her great ass. The material of her silky panties was slightly riding up into her crack and I could see the bottom of her cheeks peering out below.
As I gazed at my sister in-law's ass I could feel my erection quickly spring up in my boxers. It popped out of the opening in front and I reached down to run my hand up and down the shaft as I admired Carolyn's sleeping form. Memories of sticking my hard cock into her began flooding back and I new I had to have her. Right then and there. But how? She'd always nixed the idea when I brought it up. I remembered my wife telling me how heavy of a sleeper Carolyn is and I figured my one shot would be to make my move while she was sleeping and hopefully by the time she woke up she would be so worked up that she would go along with it.
In my highly aroused state, with all of the blood rushing from my head to the throbbing member in my hand, this seemed like a really good idea. In hindsight, it would seem like a very stupid plan, but it was the only plan I could come up with and I just had to have her again. I put my water down and tiptoed into the living room to make my move. My hard tool pointed the way, swaying and bouncing with every step. When I reached the air mattress I knelt down at the edge. It was like I was stalking my prey in the jungle and I had to be ultra-stealthy.
Now, I'm quite familiar with air mattresses but at the time I had forgotten how damn noisy they are when you get on them. As I moved onto the mattress it made that loud "body-on-vinyl" noise and I froze. I could feel my heart racing in my chest as I awaited movement from the two sleeping people in the room. Luckily it appeared that the sound of the air mattress just blended in with the sound of the TV and they didn't stir at all.
Ever so slowly I moved further onto the mattress and slid in behind Carolyn. I laid down behind her in a spooning position and began to press up against her back. I sandwiched my erection between me and her panty-clad ass as I moved up against her. Still no movement. So far so good. I nervously placed my right hand down onto her thigh and still nothing. I lightly caressed her leg, trying not to tickle her or awaken her, but wanting her to get used to being touched. As I gained more confidence I moved my hand up her smooth thigh, over her panties, and up under her shirt.
