"You don't," she said. "You're a big boy now."
Big is hardly the word for it, she thought. She hoped he couldn't tell she was blushing.
"Mind if I join you?" he asked.
"I don't mind at all. As long as you don't jump in like a clumsy whale and make too many waves," she joked. "See how calm and glassy it is?"
He nodded. She could hardly believe her eyes when she saw him unbuttoning his cutoffs. She stared at his crotch, both hoping and fearing that he was wearing trunks. He was. But he saw her staring too. His cock was so huge that it made a large bulge in his swim trunks. Kirstie wondered why she had never noticed it before. But when you're not supposed to do something, you don't do it, she thought, trying to calm herself. It was purely an accident that I saw it the other night.
Rick slid into the pool and swam gently over to her, taking care not to disrupt the even surface of the water too much.
"See," he smiled. "Did I do good?"
"You did good, little brother."
"Humph, little brother," he joked, poking her in the ribs under the water. "I'm as big as you are."
"Oh!" Kirstie cried out, losing her poise in the water and beginning to sink. "Don't do that!"
Rick watched her firm bobbing breasts as she struggled to stay afloat. The full globes bulged out of her bikini top, showing the line where her deep tan stopped and the pale skin started.
"Don't do what?" he said.
Suddenly he reached out and grabbed her waist, pulling her underwater with him. Kirstie struggled and thrashed, trying to surface. She felt her brother's hands on her body, on her breasts, squeezing them hard. She popped up and out of the water, snorting out her nostrils, gasping for breath.
"Oh, you mean little bastard!" she swore at her brother, giggling. "How could you do that to me?"
"Do what?" Rick grinned from ear to ear.
"You know what you did!" she said, feigning anger, treading water.
"I couldn't help it," he said, still grinning.
"Yes you could!"
Now he stopped smiling. His eyes were deeply serious. "No I couldn't," he said.
The situation was so exciting and embarrassing that Kirstie could only think of one way to get out of it. She took a big gulp of air and quickly dove herself, swooping under him and grabbing his legs, pulling him down. Rick kicked and thrashed, frying to get away. Kirstie reached between his thighs and gabbed everything that was there, giving it a tight squeeze.
"Jesus!" Rick gasped as he surfaced, shaking the water out of his hair. "What in fuck's name do you think you're doing?"
"In what's name?" Kirstie said coyly.
He grimaced. "You heard me."
But suddenly they were staring at each other as if they knew what all this horse play meant. To Kirstie it seemed as if she could still feel the imprint of his huge cock and heavy balls in her hand. Rick's eyes on her wet body were like tongues.
She turned her back on him, swam to the steps, and climbed out of the pool.
"Hey, where are you going?" he called, the disappointment clear in his voice.
"Inside," she said, gabbing a towel and disappearing through the glass doors.
Rick scrambled out of the pool and followed her. He found her in the living room, drying herself. He had forgotten his own towel and was dripping heavily.
"Rickie, look at you!" Kirstie laughed, pointing. "You're getting water all over Mom's rug. You know how she feels about that."
Rick suddenly looked embarrassed and confused to her. The rough horseplay in the pool he could handle. But this was more dangerous. He didn't seem to know how to act. And of course he didn't, Kirstie realized.
She didn't know why she was doing any of this either. But she knew that she couldn't stop to think about it. If she did, she would feel guilty. So she rushed on before she could have misgivings. She stretched out her hand to him, holding the towel.
"Here, dummy, come and dry off my back," she said, trying to be absolutely nonchalant. "Then you can dry yourself off."
Slowly Rick approached her and took the towel. She turned her long supple back to him. He began daubing her skin with it tentatively.
"Not like that, silly," she said, glancing over her shoulder at him. "Rub it."
"Your strap's in the way," he said, his voice thick.
"Then why don't you untie it," she whispered. Rick hesitated. But then she felt his fingers on the string. She nearly fainted with excitement. A sharp tremor seized her body. Oh God, it's really going to happen! she thought. It's so wrong! And I want it so much!
Rick's hands shook slightly as he untied the wet string. The top was so flimsy that it fell to the floor as soon as he got the bow loose. Kirstie bit her bottom lip. She tried to control her breathing as she felt him apply the towel to her skin again.
"That's it," she murmured. "That's it…"
When he reached the curve of her lower back with the towel, she slowly turned around. Her full naked breasts nearly brushed his forehead. Rick looked surprised, even frightened. But he couldn't take his eyes off the quivering globes, so pale against the brown of her tan. Her large puffy nipples were swollen and soft.
Rick tried to speak. His lips moved, but nothing came out. Kirstie didn't know what to say either. She had a feeling that a singe word might destroy the magic. If either of them let the guilt take over, they would not be able to go on. So she reached out with one hand, put it behind his head, and pulled his face gently into her breasts. Instinctively he cupped them with his hands and sucked her thick left nipple into his mouth.
"Oh yes!" Kirstie gasped.
Her body ran with fire. She threw back her head and pushed her throbbing nipples into his mouth, moaning with pleasure.
"Suck, baby, suck me, suck me," she murmured.
"God, Sis, they're beautiful!"
"Suck them, suck them hard!"
Rick squeezed her aching breasts and sucked their nipples with sharp passion.
"Ah!" she moaned. "Oh Jesus, yes! I… I want you to… to fuck me," she panted softly. "I want you to fuck me, Rickie."
His face was troubled but torn with passion for her. "We… can't do that, Kirstie. You know we can't do that."
She grabbed him and kissed his mouth wildly, snaking her tongue around his, mashing her breasts into his bare chest.
"Why can't we?"
"It's wrong."
She reached down and slid her fingers under the waist of his swim trunks, just touching the base of his bent and throbbing prick.
"Don't you want me? Don't you want to fuck me?"
"Yes, but."
"I want your cock. I want to kiss your big cock," she panted.
She slid down his body, kissing the droplets of water off his skin as she sank to her knees. She grabbed his swim trunks and pulled them down his muscular thighs in one swift motion. His huge cock jumped up and started twitching, only inches from her face. Quickly she slid his trunks down his ankles and off his feet.
"Down here," she said urgently. She patted the carpet. "Don here with me." She squirmed out of her bikini panties.
Rick sank down next to her, still mumbling half-hearted protests. "But we… Kirstie, we…"
"Shhh," she shushed him.
She closed her lips over the flaring head of his massive cock and began sucking him wildly. Oh God, oh God, I love it! I love it! But she had only sucked him a few seconds when she realized the problem. He had no control.
"God, Sis, I'm going to come!" he groaned.
"No… no," she panted, quickly letting his jumping prick out of her mouth. "Not yet, not yet. Try to hold it. Here, put it in me."
She rolled over on her back and spread her legs, pulling him on top of her. God, put it in me, don't come before you fuck me, honey!