Mom's Strapon
Copyright© 2026 by WifeFan1
Chapter 1
Incest Sex Story: Chapter 1 - Daughter uses mom's strap on sister without her permission, mom finds out and shows her how to use it
Caution: This Incest Sex Story contains strong sexual content, including ft/ft Fa/ft Reluctant Incest Mother Daughter Sex Toys AI Generated
Lynn waited until the house went quiet. Her mother’s bedroom door had been closed for an hour, the light under it gone dark, and still she sat on the edge of her bed with her phone in her hands, thumb moving across the screen without reading anything. The harness lay in the bottom drawer of her dresser under a tangle of old leggings. She’d found it three weeks ago inside her mom’s closet and hadn’t touched it since, had barely let herself look at it, because every time she did she thought of Leah and what Leah’s face would do when she understood what was happening.
The dildo was huge. That was the point. Lynn liked that it was thick as her wrist and longer than her hand, a ridiculous veined thing the color of dark black skin.
Now she took it out and laid it on the bed and looked at it for a long time. Then she put the harness on over her pajama shorts, cinching the straps until the base of the dildo sat hard against her pubic bone. She pulled her sweatpants up over it. The bulge was obscene. She looked like she’d grown a cock in the last five minutes.
She walked down the hall to Leah’s room and opened the door without knocking.
Leah was on her stomach, scrolling her phone, one bare leg kicked out of the covers. She looked up with that half-annoyed expression she always wore when Lynn came into her space uninvited, and then her eyes dropped to Lynn’s hips and the expression changed.
“What the fuck,” Leah said.
Lynn closed the door behind her and locked it.
“Mom bought this for you,” she said. “She told me to come in here and use it.”
The lie came out so easily Lynn almost believed it herself. She’d been practicing it for weeks, turning it over in her mouth until it tasted like the truth. Mom. Bought this. For you.
Leah sat up slowly. She was wearing an old t-shirt and nothing else, and the sheet pooled around her waist. “Mom would never...”
“She did.” Lynn stepped closer, and Leah’s eyes went wide. “She said you’ve been acting like a brat and you need to get fucked. Her words.”
“That’s not—you’re lying...”
Lynn put her knee on the bed. The mattress dipped. Leah scrambled backward until her shoulders hit the headboard, and Lynn followed her, crawling up the bed, and when she was close enough she took Leah’s wrist and pulled her hand down and pressed it against the front of her sweatpants.
“Feel that,” Lynn said. “That’s for you.”
Leah’s breath went shallow. Her fingers twitched against the shape of it, and for a second Lynn thought she was going to pull away, but she didn’t. Her hand just stayed there, trembling a little, and her lips parted.
“Lynn, please,” she whispered. “Don’t.”
“Mom said you’d beg.” Lynn pulled the sweatpants down and let the strap-on spring free. It bobbed between them, thick and dark and glistening with the lube Lynn had already slicked on it. “She said you’d pretend you didn’t want it.”
“I’m not pretending.” Leah’s voice cracked. “Please, I don’t—it’s too big...”
Lynn grabbed her hips and flipped her onto her stomach. Leah gasped and tried to push herself up, but Lynn was already on top of her, one hand between her shoulder blades pressing her down into the mattress, the other working the t-shirt up over her ass. Leah’s thighs were shaking. Her pussy was bare and pink and already wet, and Lynn stared at it for a moment, at the way Leah’s cunt glistened in the lamplight, and felt something hot and mean bloom in her chest.
“Look at you,” Lynn said. “Soaked. You want it.”
“I don’t—please, Lynn, please stop...”
Lynn guided the head of the dildo against Leah’s opening. Leah made a sound like a wounded animal, her whole body going rigid, her hands fisting in the sheets.
“Beg me not to,” Lynn said.
“Please don’t, please, I’m begging you, it won’t fit...”
Lynn pushed.
The head went in and Leah screamed into the pillow, a real scream, muffled but raw, and Lynn felt her own cunt clench at the sound. She held Leah’s hips and kept pushing, slow and steady, watching the thick shaft disappear inch by inch into her sister’s body. Leah’s pussy stretched around it, pink and tight and quivering, and Leah was sobbing now, her shoulders heaving, her voice breaking on every breath.
“Too big—Lynn, it’s too big, please take it out...”
“Mom said you could take it.” Lynn bottomed out, her hips flush against Leah’s ass, and held there. “She said you were made for it.”
Leah whimpered. Her whole body was trembling, and Lynn could feel the muscles of her cunt fluttering around the shaft, trying to adjust, trying to take it. She pulled back slowly, then pushed in again, and Leah moaned despite herself, a sound that was half pain and half something else. Lynn loved seeing the dark veined shaft stretch out her sister’s tight pink pussy.
“There it is,” Lynn murmured.
She fucked her slowly at first, long deep strokes that made Leah gasp and clutch at the sheets, her face turned to the side, tears streaking her cheeks. Leah was still begging, but the words were changing, losing their shape.
“Please—please, I can’t—oh—oh fuck...”
Lynn reached around and found Leah’s clit with her fingers, rubbing in tight circles while she thrust. Leah bucked under her, a full-body spasm, and the next sound she made was pure pleasure.
“Oh my god—Lynn...”
“You like it now.” Lynn picked up the pace, slamming into her harder, the sound of their bodies slapping together filling the room. “Tell me you like it.”
“I—I—fuck...”
“Tell me.”
“I like it,” Leah sobbed. “I like it, I’m sorry, I like it so much...”
Lynn grabbed a fistful of Leah’s hair and pulled her head back, arching her spine, and drove into her as deep as the strap would go.
Leah’s head snapped back, her throat bared, and Lynn watched the muscles in her sister’s neck cord and strain as she drove in to the hilt and held there, grinding. Leah’s mouth opened, but no sound came out for a long second, and then it came—a high, keening wail that didn’t sound like pain at all anymore.
“Fuck,” Leah gasped. “Fuck, Lynn, don’t stop, please don’t stop...”
Lynn let go of her hair and grabbed both hips instead, fingers digging into the soft flesh, and started fucking her in earnest. No more slow strokes, no more teasing. Just hard, fast, brutal thrusts that made the headboard knock against the wall and Leah’s tits bounce under her bunched-up shirt. The dildo was slick now with more than lube, and every stroke made a wet, obscene sound that Lynn wanted to bottle and keep.
“You’re so fucking wet,” Lynn said, and heard the awe in her own voice. “Listen to yourself.”
Leah moaned, a broken, desperate sound, and pushed back against her. “Harder. Please, Lynn, harder...”
“Say it like you mean it.”
“Fuck me harder!” Leah’s voice cracked on the last word, and she buried her face in the pillow, but her hips were working now, meeting every thrust, her ass slapping back against Lynn’s thighs. “Please, please, please...”
Lynn gave her what she asked for. She slammed into Leah so hard the bed frame groaned, and Leah screamed into the pillow, her fingers tearing at the sheets, her whole body coiling tight. Lynn could feel it building—the way Leah’s cunt started to flutter and clench around the shaft, the way her thighs shook, the way her breath went ragged and high.
“That’s it,” Lynn said, and her voice was rough, almost tender. “Come for me. Come on this big fucking cock.”
Leah sobbed something that might have been Lynn’s name, and then she shattered. Her back arched so hard Lynn thought she might snap, her pussy clamping down around the dildo in rhythmic, violent pulses, and she screamed—a real scream, not muffled this time, loud enough that Lynn felt it in her teeth. Leah’s whole body convulsed, her legs kicking, her hands clawing at the mattress, and Lynn held on through it, kept thrusting through the clench and release, drawing it out until Leah collapsed forward, gasping and shaking and whimpering.
Lynn slowed, then stopped, buried to the hilt. She was breathing hard, her own cunt aching and untouched, and for a moment the only sound in the room was Leah’s ragged, hitching breaths and the distant hum of the house.
Then Leah turned her head.
Lynn saw her sister’s face go slack. The flush of pleasure drained out of it, replaced by something white and frozen. Leah’s eyes were fixed on something across the room, and her lips moved, but no sound came out.
Lynn followed her gaze.
The door was open.
Their mother stood in the doorway, one hand still on the knob, wearing her old flannel robe and a look that Lynn couldn’t read at all. She didn’t speak. She didn’t move. She just stood there, her face half in shadow from the hall light behind her, and watched them.