I slammed the door behind me and threw my backpack on the floor. My cock was already half hard from the dirty thoughts that had been running through my head all day. I yanked open the bottom drawer of my desk and pulled out the thick sketchbook I kept hidden under a stack of old magazines. The pages were filled with raw drawings of my sister, every filthy detail I could remember from the times I had caught her changing or bending over. Big tits hanging free, round ass spread wide, pussy lips slick and open. I flipped to a fresh page and started sketching fast, my hand moving like I was already inside her.
The door creaked. I spun around and there she was, standing in the doorway with her arms crossed under her tits, pushing them up. She was eighteen, just like me, and she had that look on her face like she knew exactly what she had caught me doing.
"So this is what you do when you think no one's home," she said, stepping inside and kicking the door shut. "Drawing pictures of your own sister getting fucked."
I didn't bother hiding the sketchbook. My cock was throbbing now, pushing hard against my jeans. "Yeah," I said, voice rough. "I draw you sucking cock. I draw you bent over taking it from behind. I draw you with your legs spread and cum dripping out of your cunt."
She walked over, grabbed the sketchbook, and flipped through the pages. Her breathing got heavier as she looked at every dirty illustration. "These are fucking nasty," she muttered. Then she dropped the book, grabbed my shirt, and pulled me in. "Show me instead of drawing it."
Her mouth hit mine hard. Tongues sliding, teeth scraping. I grabbed her ass with both hands and squeezed, yanking her against my dick. She moaned into the kiss and started grinding on me. I shoved my hand down the front of her shorts and found her pussy already wet, no panties, just hot slick folds. Two fingers pushed straight inside her. She was tight and dripping.
"Fuck, you're soaked," I growled against her lips.
She reached down and unzipped me, pulling my cock out. Her hand wrapped around it and started stroking fast. "This is what you want to draw? Your sister jerking your dick?"
I answered by ripping her shirt off. Her tits bounced free and I bent down to suck one nipple hard, biting just enough to make her gasp. She pumped my cock faster. I shoved her shorts down and kicked them away, then spun her around and bent her over the desk. Her ass was perfect, cheeks spread, pussy and asshole right there on display. I dropped to my knees and buried my face between her legs, tongue driving straight into her cunt, licking up to her clit, then lower to rim her tight asshole.
She pushed back against my mouth. "Eat that pussy. Lick your sister's asshole like the pervert you are."
I stood up, lined my cock up, and slammed into her in one hard thrust. She cried out and grabbed the edge of the desk. I fucked her deep and rough, hips slapping against her ass, balls swinging.
Every stroke made wet sounds as her pussy gripped me. I reached around and rubbed her clit fast while I pounded her.
"Harder," she demanded. "Fuck me like you draw me getting wrecked."
I pulled out, flipped her onto her back on the desk, and shoved back in. Her legs went over my shoulders. I watched my cock disappear into her again and again, shiny with her juices. She reached down and spread her pussy lips wider so I could see everything. I grabbed the sketchbook with one hand, still fucking her, and started drawing quick lines with the other, capturing the way her tits bounced and how her cunt stretched around me.
She laughed breathlessly. "You're actually drawing while you're inside me?"
"Shut up and take it," I said, dropping the pencil and grabbing her hips instead. I fucked her faster, the desk creaking. Her pussy started clenching and she came hard, soaking my cock and the floor. I kept thrusting through it until I pulled out and stroked myself, shooting thick ropes of cum across her stomach and tits.
She rubbed it into her skin, then sat up and sucked my cock clean, tongue swirling over the head. "Next time," she said, licking her lips, "draw me with your cum all over my face while I swallow the rest."
We didn't stop there. That night turned into days of raw fucking whenever we could get away with it. She posed for me in every position I wanted to draw, legs spread, fingers in her pussy, mouth open for my load. I filled page after page while she rode me or took it from behind or sucked me off. The illustrations got dirtier, showing her with my cum leaking out of every hole, her face twisted in orgasm, my hands holding her down.
One afternoon she came into my room wearing nothing but an old T-shirt that barely covered her ass. She climbed onto my lap facing me and sank down on my cock without a word. We fucked slow and deep while I sketched over her shoulder, the pencil scratching paper as her hips rolled. She whispered filthy things in my ear the whole time: how she wanted me to draw her pregnant with my kid, how she wanted pictures of her swallowing load after load, how she wanted to watch me jerk off to my own drawings of her.
I came inside her that time, filling her up while she ground down and took every drop. Afterward she stayed on my lap, my softening cock still inside her, and we looked at the new pages together. The drawings were explicit as hell, every line showing exactly how we looked when we fucked.
She smiled and kissed me slow. "Keep drawing, big brother. I'll keep giving you new material."
We never stopped. The sketchbook grew thicker, the sex got rougher and more frequent, and every page captured another raw, dirty moment between us. The illustrations told the whole story better than words ever could.
