I slammed my laptop shut the second I heard the front door open. My little sister Emma walked in from college, backpack slung over one shoulder, that tight tank top clinging to her tits like it was painted on. I knew what she had been posting. I had found her secret Tumblr weeks ago, full of filthy brother-sister stories where the sister begs for her brother’s cum in every hole. She wrote them raw, no filter, detailing how she wanted her brother to pin her down and flood her pussy until it overflowed.
She had no idea I was reading every single one.
Or that I had my own account posting the same twisted shit from the brother’s side.
“Late night again?” she asked, dropping her bag. Her shorts rode up, flashing the bottom curve of her ass.
I stood up, cock already half-hard just from the sight of her. “Found something interesting on Tumblr tonight.”
Her face went pale for a second, then flushed red. “What the fuck are you talking about?”
I opened my laptop and turned it toward her. Her latest post stared back: a long, nasty paragraph about a brother forcing his sister’s legs apart and pumping load after load of thick cum deep inside her while she screamed for more. She had tagged it #brother sister incest sex tumblr stories cum.
Emma stared at the screen, then at the obvious bulge in my jeans. “You weren’t supposed to see that.”
“Too late. I’ve read every one. Every time you describe taking your brother’s cock and milking him dry, I jerked off thinking about you.”
She licked her lips. “And what did you post?”
I clicked over to my account. My latest entry was even dirtier: the brother bending his sister over the couch, spreading her cheeks, and unloading rope after rope of cum into her tight ass while she begged for it.
Emma’s breathing changed. Her nipples poked hard against her tank top. “We can’t,” she whispered, but her hand was already reaching for my zipper.
I grabbed her wrist and yanked her close. “We’re doing exactly what you wrote about.”
I spun her around and bent her over the arm of the couch, yanking those tiny shorts down. Her pussy was already dripping. I shoved two fingers inside her, feeling how soaked she was from the taboo thrill.
“Fuck, you’re wet for your own brother’s cock,” I growled.
She pushed back against my hand. “Shut up and give it to me like in the stories.”
I freed my dick, thick and throbbing, and slammed it straight into her cunt in one thrust. She cried out, gripping the cushions. I fucked her hard and fast, just like she had described in her posts, skin slapping, her juices coating my shaft. Every time I bottomed out she moaned louder.
“Tell me you want my cum,” I demanded, pounding deeper.
“Fill me up,” she gasped. “Pump every drop inside me. Make it drip out like you wrote.”
I reached around and rubbed her clit while I drilled her. Her pussy clenched tight, milking me. I felt my balls tighten and let go, flooding her with thick, hot cum. Spurt after spurt pumped into her, exactly the way our Tumblr stories always ended. It overflowed fast, running down her thighs in white streaks.
I didn’t pull out. I kept thrusting through the mess, pushing my load deeper while she came hard around me, screaming my name.
We weren’t done. She dropped to her knees, sucking my cock clean, tasting our mixed cum on her tongue. Then she climbed on top, riding me reverse so I could watch her ass bounce while she worked another load out of me. This time she aimed it at her face, letting me paint her lips and tits with fresh cum before licking it off her fingers.
By the time we collapsed on the couch, both of us sticky and spent, the laptop was still open. Her latest story post sat there, waiting for comments. She smiled, cum still glistening on her chin, and typed one more line: “This one actually happened.”
We kept going until morning, turning every filthy Tumblr fantasy into real, raw brother-sister sex, leaving her pussy and ass overflowing with my cum again and again.
