"Come on, relax," Karen whispered, hot breath. "Relax, this won't hurt a bit."

Sarah could hardly breathe. Karen's soft hands were moving along her back but then they slipped around her waist, and slowly moved upward. Sarah trembled, moist little sobs in her throat. She wanted to run away, yet she wanted to stay. Her legs shook, and she looked down at her sister's hand when she felt them moving upward.

"Please…" she panted as her sister's hand cupped her tits.

"Shhhhh," Karen whispered in her ear, squeezing Sarah's tits gently, rubbing her palms about the stiff nipples. "Just relax. Just relax and let the tension flow out, honey."

Sarah closed her eyes, feeling her tits tingle as her sister massaged them, squeezing deliciously. She stood on weak legs in front of the window, and sagged slightly. She placed her hands on top of her sister's, leaning her head back, feeling the burning wetness in the crotch of her bikini panties. Her breath came faster, and her hips started to writhe. She felt Karen's body pressing against hers, felt Karen's tits smashing on her shoulder blades, and the pressure of her lower body against her clenched ass-cheeks.

"Please, Karen…" she whispered in a little sob.

"Shhhhh," Karen whispered again, pinching Sarah's nipples gently through her dress. "Be quiet and let me relax you."

Sarah began to pant hotly when one of Karen's hands moved down from her tits, over her trembling stomach. She kept her hand on top of Karen's, and when she felt her sister's fingers pressing at her cunt, through her dress and panties, she exerted pressure with her own hand.

"I knew this was it, Sarah," Karen purred in her ear, the tip of her tongue fucking out to lick at the lobe. "I could see it."

Her fingers rubbed lightly up and down, then firmer. Sarah's cunt bulged inside her panties, and when her sister rubbed at it, she groaned softly, arching her hips into the hand. She sobbed as she felt Karen inching her dress up, using both hands now. She wanted to stop her, but she didn't want to stop her. Her cunt was on fire, as wet and hot as it had been the day she fucked her son. Sarah lost all control, just as she had that day, when her sister bunched her dress around her waist, and rubbed at her cunt through her panties.