My sister-in-law is hopelessly naive… [M31 / F25] [cheating] [groping] [sex]

Mike unlocks the door to his penthouse condo and walks inside, setting his laptop bag down on the bar chair and loosening his tie. He pops open the crystal decanter and pours himself a glass, enjoying the sweet burn of the whisky, letting it calm him after a stressful day at the office.

He looks out the floor-to-ceiling windows at the city below, the neighboring towers rising up from the thick, sweltering heat — only a few buildings soar quite so high as this one. It’s early afternoon, and his fiance Roxy isn’t due home for several hours. Coming and going on different schedules can be frustrating, but they make it work. Sometimes he even uses the time to cook her dinner, give her a nice welcome home. When he does that, she tends to reward him with something he likes, such as a hot and sloppy blowjob, the kind where she ends up plastered in his spunk.

He drapes his jacket over the back of the bar stool and steps into the kitchen. Luxury appliances are tucked flush into the high walls, the grain in their wooden faceplates continuous with that of the cabinetry. He reaches above the microwave, to the shelf where lies the recipe books, but pauses. There are sounds, he realizes, echoing out from the living room. He holds his breath and listens. But it’s just the TV. He exhales. “The maid must’ve left it on,” he mutters to himself.

With a sigh, he walks through the arched doorway and around the corner, into a large, sweeping room with plush carpeting and panoramic views. Sure enough, the TV is on, playing some cartoon show he doesn’t recognize, some anime. He frowns. Who would’ve been watching anime? Certainly not him or Roxy. And then the screen pauses, an action that only happens when someone is pushing buttons on the remote control…

“Who’s there?” the someone squeals. A head springs up over the couch, blonde pigtails bouncing. “Aiee! Mike! You startled me.”

Mike blinks at the unexpected guest, and then he groans. “Stacey. This is my–” he shakes his head. “What are you doing here?”

“Uhh… I don’t know? I hope its ok, Roxy said it was ok,” she speaks nervously, the words spilling out on top of each other, “She said I could stay in the spare room a couple days. I’m supposed to make myself at home. She’s going to take me shopping later, and then dinner, after she gets home from work. So until then, I’ve been, uh… here. Doing this. I thought I remembered your guys’ wifi password but I forgot and I got bored and I guess I could have texted and asked but I didn’t want to bug you guys so I figured out the TV and you have it all set up so I’ve just been watching shows all afternoon I hope that’s ok?”

Mike frowns. The wifi password is written on the whiteboard in the kitchen. But then, Roxy’s younger sister is always kind of spacey. Spacey Stacey. A ditz, to hear Roxy say it.

“She’s taking you out to eat?” Mike says, feeling his plans to cook Roxy dinner fade away, feeling his balls grow blue. “Like, to a restaurant? Just the two of you?” He walks around the couch, eyeing her up and down. Roxy is elegant and classy and beautiful, a perfect match for Mike’s estimation of himself. Stacey shares her older sister’s good looks, but with none of Roxy’s refinement or grace. Like now, dressed in a patterned sweater, baggy and unseasonable and decorated with anime characters. She’s paired it with a white pleated skirt, far too short, the tops of her thigh-high socks showing with their ridiculous cartoon dog motif. The outfit is preposterous, immature.

She nods.

“I guess that means I’m on my own tonight.”

Stacey looks down at the plush rug, too jittery to meet his gaze. “Uh, yeah. She said you wouldn’t mind.”

“And you’re going to dress like that?”

“Why? What’s wrong with what I’m wearing?”

He sighs and plops down on the couch next to her. “It’s– you know what? Forget it.” He sips from his whisky, changes the subject. “How was your flight?”

“Kinda bumpy, actually. A storm out west, or east, I don’t know.”

Mike blinks. Roxy’s family home is south. “I see,” he says, “But you’re making yourself comfortable here, I hope?”

“Oh yes!” Stacey lights up, “You guys have, like, every service on your TV. And the view is really good.” She points, as if Mike was confused as to which view she meant.

But he should be nice. “Thank you, Stacey,” he bows his head.

She gives him a weak smile, barely able to meet his gaze. He looks again at her outfit, the cartoon characters decorating it. “You’re, what, twenty-two or something?”

She looks indignant. “Twenty-five. Did you forget?”

He shakes his head.

“By the way,” she says, “Could you get me something to drink? I couldn’t figure out the faucet. I pushed the button on the fridge door and nothing came out. I’m kind of thirsty.”

Mike frowns, “I see.” His fridge doesn’t have a water dispenser. He looks at his glass of whiskey, smirks, “Well, you’re welcome to some of this, if you’re desperate.”

He meant it as a joke, but Stacey acts genuinely grateful, taking the glass from his hand and drinking it down in one gulp. She coughs, chokes. “What was in that?”

“Stacey,” he sighs, “You’re hopeless.”

She looks at him blankly.

He returns from the kitchen with his glass refilled and a cup of water for her. He sits down right next to her, studying the cute naivete on her face, the innocence in her eyes, the creaminess of her thighs. He holds the water out.

“Thanks,” she says, taking the cup from him. But she doesn’t get a good grip, and the drink slips and topples over, spilling the water all down her sweater and skirt, soaking her. Some splashes on Mike’s pants.

“Stacey!” he barks, like it was her fault.

“Oh my gosh, I’m so sorry!” she whimpers, looking down at the mess she believes she made.

“These are French!” Mike growls.

She looks confused, the water continuing to soak in. “The couch?”

“My suit!”

Her eyes go wide, tears build up at their rims. “I’m sorry…”

Mike grits his teeth, makes a show of being upset. “I can’t believe you. Just, ugh, take off your sweater, let’s soak this up quick.”

Mike watches her pull the wet garment off over her head, delighting in the pink tank top she’s got on, the cleavage it’s showing, her nipples poking through. He takes her wrist in his grip, guiding her hand to daub up water on his lap. Her cheeks are red with shame, her wet skirt clings to her skin. He points at her crotch. “Look, it’s everywhere,” he chastises her.

He sighs like he’s doing her a favor, taking the sweater from her, placing it on her breasts, squeezing.

“Sorry!” she says as he rubs against her tits. “I really appreciate your help, though.” He cups her chest, lifts her tits up to dry their underside, slides his hand in between them, pushes them flat against her chest, and is very thorough. His hands linger, going for a second pass, ensuring that her breasts are completely handled.

“It was a very full glass of water,” she suggests, watching him grope her.

“That’s right,” he agrees.

Mike brings the sweater down, drying her belly. Then he brings it even lower, and she gives him a look of surprise as he lifts the hem of her skirt up. Her panties are wet, too. They’re white, clinging to her pussy, letting it show through puffy and pink and shaved bare.

He licks his lips. “You really got it everywhere,” he says. He rubs the sweater over her crotch, his hand sliding down between her thighs, being as meticulous as he can.

She gasps as he pushes her knees apart, pulls them up to her sides. “I don’t want to miss any spots,” he says, “Lean back, grab your ankles.” He hums to himself, watching her comply with his instruction, feeling his mouth salivate as he studies her tight little pussy.

“Uh…” she says, “Is this good?”

“It’s ok,” he says, “You could go wider, though.” He runs his fingertips up along her inner thigh.

She gasps. “You– you forgot the sweater!”

“Thanks, Stacey,” he says, “But first I want to see how wet you are.”

Her eyes are wide as he pushes the fabric of her panties up between her pussy lips. “How bad is it?” she says.

“Well, you’re pretty wet.” With the lightest touch, his finger rests against the hood of her clit, and he begins rubbing it with slow circular movements.

She sucks a breath. “Careful! It’s a real sensitive area!”

“I’ll try to be gentle.” With his other hand, his thumb brushes the skin near her ass asshole.

She tenses, moaning, “Oh, no…”

“What’s wrong?” He runs his fingers up and down the length of her slit, pinching her lips together, then pushing between them. He keeps his expression casual, feigning disinterest.

“I’m getting… I’m getting… turned on…”

“Really? Like sexually?” With two fingers he shoves into her, pushing her panties up inside her.

She groans, “Yesssss…”

He cocks his head to the side. “How come?” He yanks her panties to the side, exposing her pussy, and, his thumb resting on her clit, he curls two fingers into her sex. With a sticky squishing sound, he slides them in to the third knuckle, groping for her g-spot. “It’s not something I’m doing, is it?”

“But you’re fingering me!”

He frowns. “Are you sure?” He impales her harder, his other thumb rubbing her asshole.

“Pretty sure,” she whimpers, her hips rocking back and forth to meet his fingers. Her pussy drips and oozes more with each thrust.

“I see,” he says, “But you’re very, very wet here.”

Stacey’s eyes go wide. “But that’s not–!”

He grins. “And you seem to be enjoying yourself.”

“I– I– Roxy’s gonna be mad!”

“Mad?” Mike chuckles, “Why would she be mad? I’m just helping you feel welcome.”

“You are?” Stacey’s whole body is bucking, her tits bouncing, hips writhing.

“Sure,” Mike reassures her, “She wanted you to be comfortable, didn’t she? And it’s not very comfortable, getting turned on but not getting off. So if that’s what you need, I guess we’ll have to have sex.”

“Sex?!”

“Mmm-hmm,” Mike says, standing up. He has a thick, fat erection tenting his pants. “I was hoping it wouldn’t come to this,” he says, pulling his dick through the flap, “But I do want to be a good host.”

“Oh! That’s… that’s…”

“I mean, it’s what Roxy wants, isn’t it?” He kneels on the couch, his legs on either side of her hips, his dick hovering over her. She stares at it, eyes wide.

“It’s so big,” She whimpers as he brings his dick down, bounces it against her swollen and wet pussy. “Are you sure my sister said this was ok?”

“Oh yeah,” Mike says. And with that, he shoves himself inside her, pressing down into her with his weight, farther and farther, not stopping until his entire shaft is inside her.

Her eyes roll back in her head, her jaw drops.

“She told me, ‘Mike, you’ve got to be nicer to my sister,’” he continues, working up a tempo, pumping his cock in and out of her tight heat, “But, knowing you, you probably planned this whole situation out,” He grabs her nipples, tweaks them with his thumbs, makes her squeal. “Pretending to spill the water. Having me mop you up. All just an excuse to get me to fuck your brains out.”

“I didn’t mean toooonnnggg…” she moans.

“But now we’re in it, right?” he continues, adjusting his angle, skewering her fast and hard. “I can’t have you telling Roxy that you needed dick, and I did a bad job of it.” His cock is slick with her juices, a thick piston shoving her open. He yanks her tank top down, popping her large breasts free of the fabric. “Fuck, you’re tight. Grab my balls, would you? Give them a little squeeze.”

She does, fingers wrapping around his heavy, swinging sac, and he groans in pleasure, ramming his cock in her even harder. “Oh, fuck yes, that’s perfect, Stacey, keep your hand there.”

Her grip on his balls tightens. “You’re making me cum!” she squeals, torso writhing, tits rolling side to side.

“That’s a good girl,” he coos, rubbing her clit as he fucks her, seeing her through her orgasm. Her pussy spasms around his shaft. He groans, “Oh, fuck, that’s good.”

Her climax continues and continues, the delirium of bliss washing through, all stemming from his dick shoving deep inside her. It’s more than Mike can take for long, and he knows this. When he feels the apex approaching, he pulls his shaft out and rubs the head of his cock against her swollen pussy.

The first load bursts from his cock, spraying up and over Stacey, hitting her squarely in the eye. She yelps in surprise, her jaw dropping, just in time for the second load to spray all over her face. The third and fourth and fifth do the same, launching onto her tits, thick white loads of sticky semen jutting across her. By the time he’s finished cumming, she’s dripping head to belly, filthy with a coat of his seed.

“It’s so much…” She looks at him in disbelief. “Why didn’t you cum inside me?”

He shrugs, collapsing on the couch next to her. “Better go clean yourself up before Roxy gets home,” he says, “Next time I’ll let you swallow my spunk like a good little girl.”

Source: reddit.com/r/eroticliterature/comments/10a5x85/my_sisterinlaw_is_hopelessly_naive_m31_f25