She had always been the quiet one in the family, the older sister who kept to herself after turning twenty-one and moving back home for a while. The house was empty most days, just her and the big, muscular German Shepherd named Rex that her brother had left behind when he went to college.
At first it was innocent. She let Rex follow her around the house, scratching behind his ears while she watched TV. Then the nights got longer and lonelier. One evening she caught herself staring at the way his powerful body moved, the thick sheath between his hind legs swinging as he walked. The thought hit her hard and dirty: what would it feel like?
She started testing it slowly. Wearing nothing but a thin tank top and panties, shed sit on the floor and let Rex nose between her thighs. His hot breath through the fabric made her wet fast. She pulled the panties aside one night and gasped when his rough tongue dragged straight over her clit. It was too much and exactly what she needed. She spread her legs wider, grabbed his collar, and let him lick her until she came shaking on the living room rug.
After that, there was no going back. She started stripping completely as soon as she got home. Rex learned the routine quick. The moment her clothes hit the floor he was there, pushing his muzzle into her pussy, licking deep with that long, wet tongue. Shed moan loud and filthy, telling him exactly what she wanted. Lick that cunt, boy.
Get it ready for you.
One afternoon she got on all fours in the bedroom, ass up, and reached back to guide him. Rex mounted her without hesitation, his front paws gripping her hips. She felt the hot, pointed tip of his cock jab against her before it found her entrance and slammed in. He was thick and relentless, fucking her in hard, fast thrusts that made her tits swing and her voice crack. The knot swelled fast, stretching her open until it locked inside. She came screaming, cunt pulsing around him while he pumped hot cum deep into her.
They fucked like that almost every day. Sometimes she lay on her back on the bed, legs spread wide so he could mount her missionary style, his weight pinning her down while his cock drove in and out. Other times she stayed on all fours for hours, letting him knot her twice in one session, cum leaking down her thighs when he finally pulled free. She talked to him the whole time, raw and direct. Fuck your sisters pussy, Rex. Fill me up. Dont stop until that knots buried.
The risk made it hotter. Shed leave the curtains open a little, imagining someone could see her getting railed by the family dog. She came harder thinking about it. Rex didnt care. He just kept mounting her whenever she presented, his heavy balls slapping against her as he bred her like she was his bitch.
By the end of the month she was addicted. Every evening ended the same way: naked, on her knees or back, taking everything the dog had to give. His cum dripped out of her for hours afterward, a sticky reminder of how far shed gone. She didnt feel guilty. She felt satisfied in a way nothing else had ever managed. The house stayed quiet, but her body stayed marked by the secret she kept with Rex.
