The first time Laurel found out Sara's breasts were sensitive, it was when they were teenagers and Laurel got insecure about not developing as early as some of the other girls in her class.
She came bounding into the bathroom when she heard the water shut off--not knocking, of course--and pulled off her top. Laurel stood there, naked in the bathroom, and Sara turned around, scandalized. She was naked as the day she was born too, and wet.
"They're just not as big as they should be, right?" Laurel asked, poking at her little tits, with a scowl on her face.
"Laurel! Relax, you're only thirteen. You'll have the rest of your life to develop." Sare turned to get the towel of the hook when she felt Laurel cup her left breast.
"Laurel! What the hell?"
Laurel gazed at her sister's breasts, how very round they were, and heavy in her hands. The nipples were a pink-ish brown and starting to harden in her hand. She gave an experimental squeeze, and poked at the hardness, pinching and rolling the nipple. She hadn't been looking at Sara's face though, but she heard the moan Sara let out, how very unsteady the other girl seemed under Laurel's ministrations, needing to lean against the sink. Laurel pinched and squeezed the left breast one final time, before she moved onto the right, squeezing the breast before pinching and rolling the nipple.
Her sister rushed her out of the bathroom then, Laurel not really understanding what happened.
Years later, of course, she'd look back on that night and understand the desire to get her mouth on her sister's breasts, to suck on them, and play with them. Some of the fantasies that got her off with just a touch to her clit were the fantasies she had of Sara and her breasts.
When her sister finally returned from the dead, everyone having thought her lost at sea, Laurel sneaked into her sister's room, intent on finding just how sensitive her sister's breasts were.
"Laurel," she started, the same exasperated tone she's used her whole life when she rolled over, and saw who it was.
Laurel's hands wandered under the covers to get her sister's nightgown off, but her hands only found bare flesh.
"You sleep in the nude?"
"Yes, I get warm during the night," she replied, unapologetic.
Laurel's delighted chuckles filled the silent room.
"Laurel, what are you doing?"
Her hand had found their prize: kneading her sister's breast, relishing the squishy feel of them in her hands. Sara's breasts were big, bigger than Laurel's hand. They felt warm to the touch too.
"Lau-rel, seriously...stop it." And then Sara did something wonderful: she writhed under Laurel's touch, a jolt of electricity running through Laurel's whole system at the reaction. She licked her lips, and bit Sara's breast, just a gentle touch of teeth at first, then a harder chomp, then swiped the flesh with her wet mouth to ease the ache. Her mouth closed around a nipple, while her hand played with the other, pinching it and rolling it. She enjoyed the delicious gasps she wrought out of her sister when she flicked at the nips with her teeth, and sucked on the squishy flesh.
She moved onto the other breast, her long hair brushing Sara's chest before she did the same thing to the right breast she did to the left...She couldn't take it anymore though, and only got to biting Sara's breast before she couldn't control herself, and started sucking on the breast with a frenzied fervor. Sara came, underneath her, with a loud, surprised shout. Laurel became breathless with desire, and pressed her face between the breasts, just inhaling the sweet smell of them, and trying to get her heart rate back under control.
Laurel's finger moved to her sister's vagina, fingering the wet pussy. She brought her wet fingers to her mouth and licked clean the secretions, sucking on her fingers the same way she sucked on her sister's breast.
Laurel thought this would be the end, but Sara got up, turned on the light, and got a strap-on out of the drawer. With a determined look on her face, she said, "This time we're doing this with the lights on, with you completely naked too, and riding me into the mattress preferably."
Laurel got her sister off for a second time that night. And many other nights too.