Her sister was splayed out naked on her Dad's bed, rubbing a buzzing toy between her legs, oblivious to everything but her own pleasure.

Cassi stood there in shock, watching her as she stimulated herself. Until a low voice sounded behind me.

"We thought you wouldn't be home."

Cassi jumped. Dad!

"She's getting herself ready. She likes to cum a few times before I take her. Says it makes her tighter. I agree."

Cassi was mute in astonishment.

"Go on in, see." Her Dad's hand was on her shoulder guiding her through the door as her sister looked up, eyes half closed. She looked at Cassi, then at her Dad, then back to Cassi, locking eyes as she came.

"It's so beautiful. So sexy to watch. Isn't it?" Cassi's Dad said as she bucked against the toy.

Cassi couldn't help but nod. Her Dad's hand hadn't left her shoulder. Now his other was on her hip.

"I first saw her doing it two years ago. Pretty much when she was your age now. I think she knew I was watching her." He said.

Cassi's Dad's hands slid slowly forward. Her sister subsided, shuddering, then began moving the toy again. Sweat beading on her skin, looking more wanton by the second.

"Did you know I watch you, too?"

His hands slid over Cassi's breast and crotch at the same time.

"Dad!"

"It's Ok, Cassi. It's all OK. Just watch. Just feel."

She watched. By the time her sister screamed and came a second time, Cassi's blouse was open, her skirt and panties in a puddle on the floor. Her Dad's hands were on her bare skin. she was soaking wet.

Her sister started again, sounding animalistic, desperate, and Cassi's Dad's fingers slipped inside her. Oh God! As if on their own, Cassi's hips pushed into his hand.

"Daddy... I need you." Her older sister sounded like a little girl. Almost whining. She'd thrown the toy to the side, and had her legs spread obscenely, her swollen, wet pussy open and glistening.

Cassi's Dad's hands left her as he stepped around her towards the bed.

"Watch. Feel," he said to Cassi as he passed. Then, "Daddy's coming, sweetheart."

He shed his pants as he stepped to the bed, and then practically leapt onto her. She screamed as his cock speared her, and she grabbed onto him, wrapping her arms and legs around him as he started fucking her like a savage.

All Cassi could do was stare, while her pussy tingled. The toy was still buzzing, forgotten, by the side of the bed. Still watching her father fucking her sister, she reached for it.