What I got was a full on view as Sophie very deliberately bent forward to make her nightie lift and show off what she had beneath, or rather, what she didn't, her knickers. I must have been gaping like an idiot as I took in the view, of her bare pink bottom with her cunt lips pouting from between her thighs and her little tight arsehole on plain show between her cheeks. She saw, laughed, and ran off up the last few stairs, the tuck of her cheeks still exposed beneath the hem of her nightie, which was when Mark spoke up.

'Don't be such a tart, Sophie. My friends don't want to see your bottom and bits.'

I did, badly. That night I masturbated myself sore over the glimpse she'd given me and fantasies of what her knowing, impudent attitude might imply. After all, if she was going to show off like that, what other treats might she be prepared to offer? I imagined her posing for me on the stairs, giggling as I tugged myself to an urgent orgasm over her rear view. I imagined her kneeling to provide a yet better view, with her nightie pulled up to add her sweet little tits to the display. I imagined her squealing in shock and delight as I lost control and spunked up all over her delightful little backside, or thrust my cock to the hilt up her tight pink cunt or better still, her anus.

That first peep was one of many, although few were quite so fine. Her father was a businessman and abroad more often than not, while her stepmother was one of those indolent, sophisticated women who care only for themselves. Certainly she was extraordinarily casual about the way her stepdaughter dressed, in tiny, clinging denim shorts that left a good deal of soft pink cheek peeing out around the hems, or in light summer dresses and skirts with no panties beneath, or if she did wear panties, then not a stitch besides. Casual, yes, but not completely oblivious, and while Caroline Brown's own style was more refined it was scarcely less tempting.

Mark and I used to drink together regularly, and I did enjoy his company, but I freely confess I'd have called less often had it not been for the presence of his sister and stepmother, because Sophie was almost guaranteed to provide a flash of titties or bum, while Caroline was well worth watching for her own sake. She favoured slacks, belted at the waist and loose at the hip, but clinging prettily to the cheeks of her bottom, which were small and pert although notably more fleshy than her stepdaughter's, but they had a pool and she was often in a bikini.

There was definitely an element of competition between Sophie and Caroline, and something more, a tension that went beyond the normal resentment you might expect between a girl and a young stepmother. I used to wonder about the two of them, and all the more so following an incident one spring afternoon in 'seventy-seven. When I came to the house Mark was out, but Caroline invited me in to wait, offering me a glass of cold beer and suggesting that I keep her company by the pool. Sophie was already in the water, splashing happily about in nothing but a pair of little white panties. As usual, she immediately began to show off, deliberately hauling herself out of the pool to let me admire how lovingly the wet cotton clung to her delightful little bottom. For once Caroline reacted, waiting until Sophie was out before sending her indoors with a well aimed smack to one wet bottom cheek and telling her that she was much too old to be running around to all intents and purposes in the nude.

Sophie went in, laughing, to leave Caroline and me alone, but a couple of minutes later I caught a movement in the corner of my eye from one of the upstairs windows. By then Caroline had shrugged off the housecoat she'd put on to answer the door and was lying face down on a sun lounger in nothing but a small black bikini that did very little to hide her figure. I did try not to stare, but I was wondering why Sophie hadn't come back out in something more demure - if the word can be applied to a girl who'd have looked the little flirt she was if dressed in a nun's habit.

It had already occurred to me that Caroline might appreciate a little casual male company, so long as she could remain firmly in control of the situation, but I lacked the confidence to try my luck. She didn't, first undoing the strap of her bikini top to leave her back naked to the sun and then asking me if I'd rub some sun tan lotion in for her. I obliged, as any red blooded man would, and was soon kneeling beside her as I massaged the oil into her shoulders, all the while with Sophie still watching from her bedroom. If Caroline knew we were being watched she gave no indication of it, and while I felt a little uneasy about the situation, my cock had no such qualms. Just to touch Caroline's skin was enough to make me start to swell, along with the sight of her bottom in her bikini pants and the memory of Sophie's in wet panties.

I wasn't sure if Caroline was game, but I had to find out. Certainly she didn't seem to mind me massaging the sun tan lotion into her back, even when she had an ample coating. She made no objection when I moved to the nape of her neck, an area which may lack obvious visual appeal but should never be neglected. When she lifted herself onto her elbows to tug her bikini top away from under her breasts I still thought she might be teasing, or merely enjoying her power over a young and eager male, but when she asked me to do her legs and let them come open a little I knew I was onto a good thing, and if Sophie wanted to watch me with her stepmother, that was up to her.

Caroline was sighing gently as I oiled her legs, working up from her feet to her thighs, slowly but surely, for all that my cock felt ready to explode. I'd already done the small of her back, so that only the first swell of her bottom and the turn of her cheeks remained unoiled, both areas far too intimate for a casual touch. Just to be absolutely certain I was welcome, I poured the oil on first, making a little pool in the shallow dip of her spine and laying a trail to where her bikini hid the top of her slit. She made no objection, or when I began to rub the oil in, even when I turned her bikini pants down a little to expose most of her cheeks.

With that I was certain, and a dozen watching daughters wouldn't have stopped me as I pulled out my cock and guided Caroline's hand to take hold of me. She gave a faint tut, perhaps of amusement, perhaps of mock disapproval, but she began to pull on my shaft, and as I took hold of her bikini pants to pull them down her legs she obliged by lifting her hips. Now I had her bare bottom to play with while she masturbated me and the only question was how far I could go. A surreptitious glance to the upstairs window showed Sophie's hair, so I knew she was still watching, and that was now exciting as I prepared to have her stepmother in front of her.