I think she had her new bikini on for less than three minutes in total before it was on the bottom of the pool where my shorts immediately followed it. I pinned her against the side, she lifted one leg and I wriggled my cock into her, standing, then we pulled at each other's hips with our hands to fuck each other.
I watched her. I saw raw lust in her flashing eyes, felt the warmth and wetness of her pussy on my cock. We fucked luxuriously, with no urgency: We were secluded here, so our moans and groans were private. We watched each other's face throughout those five or six minutes until her eyes closed in the buildup to her orgasm. Mine I kept open. I watched her frown, bite her bottom lip, and start to pant. Just before she came she opened her eyes and met mine, and for the first time we came together, thrusting at each other under the water, our loins joined together.
In the cool water my erection faded quickly. Tanya giggled as it fell out of her quim, then kissed me on the lips. I asked her: "I guess you got over your doubts then?"
She said: "Nah, this was a goodbye fuck." Then she burst into laughter as she saw the momentary pain on my face, then I laughed with her too: "I swear one day I'll slap your ass so hard..."
"Oooh will you now?"
We hugged, and swam naked. At one point I was supporting her to float on her back, loving how the water lapped at her tits, then I held her like that with one arm while I touched her pussy with the other hand. It was warm, wet, and my finger slid in easily.
"You trying to get me horny again, squirt?"
"Maybe."
She splashed away from me, ducked under the water, and took my cock in her mouth. It was electric. Her mouth felt hot on my cool dick, and it had the inevitable result. Of course she couldn't stay down there, so when she came up for air she pulled me over to the side of the pool. She had me hold onto the wall while she pushed me up. I realised what she was doing and hauled myself up to sit on the edge.
Tanya got between my legs and supporting herself with arms on my thighs, she began sucking my cock. She was quite fast, almost wanking me with her mouth. She kept up the pace for a couple of minutes, then my twitching thighs signalled my imminent ejaculation. Tanya stroked my cock quickly and watched as my jets spurted up, over her hand, onto my thighs. She smiled at the power it gave her. She washed the spunk off with pool watre then licked the end of my knob before taking my cock in her mouth again.
I stroked her wet hair. She looked up at me: "Not bad. Might let you cum in my mouth one day. Wanna repay the compliment?"
I just fell into the water and lifted my sister up so she was bent over the edge of the pool on her stomach. I got behind her, spread her ass cheeks and buried my face in there. I licked at her pussy, her clit, and occasionally got a big moan when I tongued her asshole. I expected it to be gross, but it only tasted of pool water.
I put two fingers in her pussy and licked her asshole. I changed it around. I nosed her ass while I pushed my tongue in her pussy. All the time she cooed and moaned softly, until I was rewarded with tensed thighs and a little shiver through her bum cheeks as she flicked into a brief orgasm.
She slipped beside me in the water and kissed me. She looked at me and said: "I was wondering what it would taste like."
"Your pussy?"
"Hell no. I've tasted pussy before... Oh I'll tell you one day you big perve. I never had a tongue up my ass before though. Was it OK?"
"Not horrible, but not strawberries and cream either."
"Haha! C'mere you dick!" She put her arms around my shoulders and her legs around my waist. She kissed me, and said: "I thought about it while I was shopping. Us, and incest. If you meet someone, or I do, and we do the whole picket fence and tiny tots and suburban grind thing with them, well, so be it. Maybe we'll still fuck, maybe we won't. But if not, well, this is nice, isn't it?"
"No. Not nice. Terrific."
We kissed like lovers before we broke off. She said: "Come inside. I bought steaks and stuff. You can barbecue. You're gonna need your strength, boy..."