The Afternoon My Sister-in-Law Changed Everything Between Us

Sofía was eighteen and lived in that vague zone between adolescence and adulthood where everything seems provisional. She was in her final year of high school, slept late when she could, and had very little to think about beyond her exams and her vague summer plans. She was slim, dark-haired, with that kind of beauty that still doesn’t know it has it.

Valentina was something else. Twenty-five years old, black hair to her shoulders, dark eyes that always seemed to be evaluating something without anyone noticing. She had been with Marcos, Sofía’s older brother, for five years, and to the family she was already part of the furniture, even though nobody had said it out loud. She came for Sunday dinners, stayed over when Marcos got home late from work, helped with the grocery shopping, and argued about TV shows on the sofa as if she had always lived there.

Sofía loved her like an older sister. And Valentina treated her like a friend, which sometimes left Sofía with an unease she didn’t know how to name.

***

That Friday Sofía woke up around noon. The house was clean, the floor had been freshly swept, and it smelled like fresh coffee. Her parents had left for work early, and Marcos had too. Only the two of them were left.

—I thought you were going to sleep until three —Valentina said from the kitchen when she heard her come down the stairs.

—Don’t exaggerate —Sofía replied, rubbing her eyes.

—There’s cereal on the table. Sit down.

Sofía sat down and ate breakfast slowly while Valentina finished folding a blanket on the living room sofa. They talked about nothing important: a show Valentina wanted to watch, a girl at school Sofía couldn’t stand, the heat they’d had that week. It was one of those conversations that flow on their own because neither of them is in a hurry.

—Hey —Valentina said suddenly—, what do you have to do today?

—Nothing.

—Perfect. Come with me to the mall. I want to look for some clothes.

Sofía had no reason to say no, so she went upstairs, showered, and got dressed. Half an hour later they were in the car.

***

They spent almost three hours at the mall. Valentina went into each store with the calm of someone who wasn’t in a hurry but knew exactly what she wanted. Sofía followed her, gave her opinion when asked, and took the chance to buy some dark jeans and a top she’d been looking at online for weeks without making up her mind.

They ate at a burger place on the second floor. Valentina ordered without looking at the menu. Sofía took five minutes to decide. They talked about Marcos, how much he’d been working lately, and how Valentina wanted the two of them to go on a trip in August somewhere near the sea.

—Have you ever traveled alone? —Valentina asked her.

—No. Not yet.

—You should. It changes something in the way you see yourself.

Sofía thought about that while she finished her soda. It was the kind of thing Valentina said sometimes, phrases that sounded like advice but could also be something else. As if she knew more about Sofía than Sofía knew about herself.

They got home around four in the afternoon. They left the bags on the coffee table in the living room and sat together on the sofa to look over what they’d bought, taking out each item and comparing them.

***

Valentina took a black lace top out of her bag, very low-cut, with the seams visible along the sides. She held it up in front of herself for a moment and then, without saying anything, took off the blouse she was wearing. She did it with complete naturalness, as if Sofía weren’t there, or as if her presence didn’t matter.

Sofía looked away at once. She looked back almost immediately, unable to help herself. Valentina’s breasts were generous, firm, with dark nipples already hard from the room’s air.

Valentina took off her bra too in one quick, fluid motion, put on the lace top, and turned toward Sofía.

—How is it?

The lace was so fine that her nipples showed clearly through the fabric, the areolas dark beneath the black lace. Sofía focused on the neckline of the top.

—It’s nice. It suits you.

—Do you think Marcos will like it?

—I suppose so.

Valentina smiled, took it off without hurrying, pulled another bra out of the bag —this one red lace, just as skimpy— and put it on while looking at Sofía with an expression that wasn’t exactly curiosity, but wasn’t innocent either.

—And this one?

Sofía felt her face grow hot. She shrugged.

—That’s nice too.

—Come on —Valentina said—, you try on what you bought too. We’re among women, no need to be shy.

Sofía hesitated. Then she stood up, turned her back to Valentina, took off her T-shirt, and unfastened her bra. She took out the one she had bought and started putting it on.

—Wait —Valentina said behind her—. That doesn’t fit you right like that.

Sofía felt Valentina’s hands on her back before she could answer. The hands adjusted the straps, ran along the clasp with the pads of her thumbs, and then moved to the sides to settle beneath her breasts from below.

—It was fastened wrong —Valentina said in a low voice, very close to her ear.

Sofía didn’t answer.

Valentina’s hands were no longer adjusting anything. They were squeezing slowly, with a pressure Sofía didn’t know how to interpret. Her thumbs brushed Sofía’s nipples and Sofía felt them harden instantly, betraying her. She took a step forward, moving away.

—There —she said—. I’m going to my room to try everything on properly.

She went to the sofa to collect her bags. She didn’t make it there.

***

Valentina grabbed her from behind by the shoulders and turned her firmly until Sofía’s back was against the wall. It wasn’t rough, but it wasn’t gentle either. Sofía stayed still, her back pressed to the wall, looking at Valentina without fully processing what was happening.

—Valentina —she said.

Valentina didn’t answer. She leaned in and kissed her.

Sofía turned her face away. Valentina kissed her again, slower this time, as if she had all the time in the world and didn’t care in the least that Sofía was trying to dodge her.

—Stop —Sofía said.

Valentina pulled back a centimeter. She looked her in the eyes. Then, without breaking eye contact, she put her forearm across Sofía’s chest —not forcefully, but with a firmness that left no doubt about her intent— and with her other hand began to stroke between her legs, over the fabric of her jeans, pressing her palm right over her pussy.

Sofía squeezed her thighs together hard. Valentina applied a minimal pressure with her forearm, enough for Sofía to understand that wasn’t going to work.

—Relax —Valentina said in a very low voice—. Open your legs.

Sofía clenched her teeth. Valentina’s hand moved with deliberate slowness, pressing, rubbing Sofía’s pussy through the denim, unhurried. Sofía felt the heat in her face move down her neck, her chest, through her whole body, until it gathered there, at the exact point where Valentina’s palm insisted.

She didn’t want to like it.

She liked it.

Her legs gave way a little. Valentina noticed the change and sped up, pressing more firmly, drawing circles over the clit through the fabric. Sofía felt the fabric grow wet —a hot, sticky dampness seeping through the denim— and closed her eyes, ashamed of it, completely unable to stop it. A sigh slipped out of her that she tried to contain too late.

—See —Valentina said against her mouth—. I knew it long ago. You’re soaking.

When Valentina kissed her again, Sofía didn’t turn away. She didn’t respond to the kiss, but she didn’t reject it either. She felt Valentina’s tongue brush her lips, exploring patiently, then slip slowly into her mouth, searching for her tongue. Sofía let herself go, and without fully meaning to, started to respond, timidly at first, letting her tongue tangle with Valentina’s.

Valentina slid her hand under the waistband of Sofía’s jeans, inside her panties, and brushed her fingers directly over the lips of Sofía’s pussy. Sofía jolted and let out a short moan against her mouth.

—Look at you —Valentina murmured, sliding two fingers through the wet slit—. Dripping. My little sister-in-law dripping for me.

She ran a finger over the clit, very slowly, in circles. Sofía threw her head back against the wall and parted her legs instinctively, giving her more room. Valentina lowered her fingers and pushed one all the way in, to the hilt. Sofía felt the invasion with a clarity that stunned her.

—Ah —she said.

—Shh.

Valentina slid the finger in and out a couple of times, checking how wet she was, and then pulled it out. She brought it to her mouth in front of Sofía and licked it calmly, never taking her eyes off hers.

—Let’s go to the bedroom —she said.

***

She took her to Marcos’s room.

Sofía didn’t protest. Valentina took her by the wrist with one hand, walking ahead of her, and something in that gesture —her certainty, the normality with which she did it— made Sofía follow her without opening her mouth.

In the room, Valentina made her turn around, unclasped her bra, and let it fall to the floor. Then she stood in front of her and looked at her for a full second, openly, as if she were finishing deciding something. She ran her thumb over her lower lip while her gaze traveled over Sofía’s body, stopping on Sofía’s small breasts, on her pink nipples already hard.

Sofía didn’t know where to put her hands. She let them hang at her sides.

—What pretty tits you have —Valentina said—. Small, but the kind you can eat in one bite.

She gently pushed her against the wall and lowered her head. She started kissing her neck, her collarbone, the top of her breast. Sofía felt the heat of her mouth moving slowly, the light pressure of her teeth on the curve of her breast. She clenched her jaw to keep quiet and failed: a short, deep sound escaped her throat.

Valentina kept going down. She ran her tongue over both breasts with care, licked the nipples with a slowness Sofía found almost unbearable, nipped them lightly. Her skin prickled all over. Then she sucked one fully, drawing hard, pulling the nipple deep into her mouth. Sofía let out a short moan and grabbed the back of her neck without realizing it. Valentina let go of the nipple with a wet smack, leaving it shiny with saliva, and moved to the other one. She sucked, licked, bit, and in the end sucked hard over the white skin of her breast until it left her a pink hickey that darkened after a few seconds. She repeated the gesture in two other spots, marking her calmly, like someone signing something.

Sofía rested the back of her head against the wall and stared at the ceiling with wide eyes.

This shouldn’t be happening.

This shouldn’t be happening and yet I don’t want it to stop.

Valentina knelt in front of her and unfastened her jeans. She pulled the zipper down with her teeth, looking up at her, and then tugged the denim down to her knees. Sofía’s panties had a dark, round patch in the crotch. Valentina gave a low laugh, not mocking, brushing her nose over it.

—You’re soaking, baby. Look how wet you made your panties.

She pressed her mouth to the fabric and licked over it, pressing her tongue against the bulge of her clit. Sofía let out a whimper and buried her fingers in Valentina’s hair. Valentina kept going for a few seconds more, leaving the fabric stuck and transparent, and finally pulled her panties and jeans down together to her ankles.

She took her by the wrist and led her to the bed. She made her lie down at the edge of the mattress, with her legs dangling, and knelt on the floor in front of her. She took off the rest of her jeans and panties, leaving her completely naked on her brother’s bed. Then she parted her legs all the way, placing each thigh over her shoulders.

Sofía closed her eyes.

—Look at me —Valentina said—. I want you to look at me.

Sofía obeyed. She lowered her head and found Valentina’s dark eyes between her open legs, Valentina’s mouth a centimeter from her pussy.

Valentina’s mouth came first softly, exploring with her tongue from the inside of her thigh upward, taking her time. Sofía held her breath. Valentina ran her flat tongue over her slit, bottom to top, very slowly, collecting how wet she was in a single stroke. Then she did it again. And again. Sofía felt the tongue sink just barely between the lips of her pussy, tasting her, teasing her.

—You taste so good —Valentina murmured, speaking against the wet flesh—. I knew you’d taste like this.

And then she found the clit and stopped going slowly. She caught it between her lips and sucked it, first with a soft suction, then harder, alternating with the tip of her tongue, which lashed at it in quick, precise flicks. Sofía dug her fingers into the sheets. The moans came on their own, first short and muffled, then longer, and when she tried to silence them by bringing a hand to her mouth she realized she had already let go of the sheets without noticing.

Valentina didn’t stop. She licked and sucked with absolute concentration, sucking the swollen clit, pulling back to run her whole tongue over Sofía’s pussy from top to bottom, then going back to sucking. Sofía’s breathing broke into uneven gasps. Valentina pushed a finger inside her. Then two. She curved them upward, searching for that exact spot, and started moving them with a steady rhythm while continuing to suck her clit without pause.

Sofía arched her back instinctively, lifting her hips against Valentina’s mouth.

—Oh my God —she said—. Oh my God, don’t stop.

—I’m not going to stop —Valentina answered, pulling away for a second, her mouth and chin shining—. I’m going to make you come on your brother’s bed.

She buried her face back in Sofía’s pussy. The fingers went in and out with a wet, obscene sound that filled the whole room. Sofía felt Valentina’s palm brush her clit each time she pushed her fingers deep, and then her tongue would attack directly again, alternating long licks and quick sucks.

—Valentina —she said, and it wasn’t a protest.

—Come for me. Come in my mouth, baby.

The orgasm arrived without warning, or it arrived with plenty of warning and Sofía simply refused to acknowledge it until the very end. She felt it building from within like a tension growing tighter and tighter, more urgent, until it snapped in a shudder that ran through her entire back. She clutched the sheet with both hands, closed her thighs around Valentina’s head without being able to help it, and let out a long, guttural moan that she didn’t try to contain. Her pussy tightened around Valentina’s fingers, squeezing them, while the tongue kept working her hypersensitive clit.

Valentina stayed with her until the end, unhurried, letting Sofía’s body finish on its own. When the contractions eased, she pulled her fingers out carefully, gave her a last soft kiss on the soaked pussy, and stood up from the floor. She wiped her mouth with the back of her hand and ran her tongue over her lips, tasting what remained.

—Delicious —she said.

Sofía was still lying there, staring at the ceiling, her heart still racing, her legs open with no strength to close them, her pussy throbbing.

***

Valentina sat beside her on the edge of the bed. She brought her fingers —the same two that had been inside Sofía, glistening with fluids— to Sofía’s lips and rested them there gently. It was an odd gesture, almost symbolic. Sofía opened her mouth without thinking and sucked them, recognizing herself, tasting her own salty, thick flavor on her tongue. Valentina moved them slowly inside her mouth, to the back, watching her.

—Good girl —she said.

She withdrew them slowly, drawing out a fine thread of saliva.

—Change the sheets before Marcos gets here —she said—. And get dressed.

It wasn’t said cruelly, but it wasn’t tender either. It was a clear instruction, given by someone who didn’t expect to be argued with.

—Yes —Sofía said.

Valentina stood up, adjusted her bra, put on her blouse, and left the room, closing the door behind her with a soft click.

***

Sofía stayed still for a moment, staring at the ceiling. Her legs felt heavy. Her breasts had a lingering sensation, half heat, half sting, where Valentina had left her marks. Between her legs she still felt the dampness, dense, running down the inside of her thigh.

She sat up slowly. She removed the sheets —there was a dark, wet stain exactly where her ass had been—, threw them into the laundry basket, took clean ones from the closet, and remade the bed with automatic movements. She picked up her clothes from the floor, clutched them in a bundle with both hands, and stepped out into the hallway.

Valentina was on the sofa, looking at her phone. She looked up when Sofía passed through the living room, and Sofía lowered her head without anyone telling her to, as if the weight of that gaze were something solid.

She locked herself in her room. She sat on the bed and stared at the opposite wall.

I don’t know what to feel.

There was fear, yes. And also something that wasn’t exactly shame, but was very much like it. And beneath all that, persistent and impossible to ignore, a feeling of heat between her legs that had nothing unpleasant about it. Her pussy was still throbbing, swollen, sensitive to the brush of her clothes. That was what disconcerted her most.

She got dressed, combed her hair in front of the bathroom mirror without really looking at herself, and went down to the living room. She sat in the small armchair, the one seat that was far from the sofa where Valentina was still on her phone.

—Shall I put something on the TV? —Valentina asked after a while, in the same kind voice as always, as if the afternoon had been a completely normal afternoon.

—Whatever you want —Sofía replied.

Valentina chose an action movie. The two of them watched it in silence for almost half an hour without exchanging a word.

***

Marcos got home when the movie had been on for about forty minutes. He came in greeting them with the energy of someone who arrived tired but in a good mood, left his keys in the bowl by the entrance, and looked at the two of them from the living room doorway.

—How was your day? —he asked.

—Good —Valentina said—. We went to the mall.

—Did you spend a lot?

—A little —she replied with a smile.

Marcos came over, hugged her from behind the sofa, and kissed her neck with that routine, affectionate gesture couples have when they’ve been together a long time. Valentina closed her eyes for a second.

Sofía looked at the screen.

Marcos went to change clothes. Valentina followed him to the room. Sofía heard the door close and then, a few minutes later, the sounds she already knew from other times: the soft creak of the bed, a few murmurs, and then Valentina’s moans, this time louder than usual, with no effort at all to keep her voice down. You could hear perfectly the rhythm of the thrusts, the headboard hitting the wall, Marcos’s voice grunting low. And above all Valentina’s voice, gasping higher and higher, moaning things Sofía couldn’t quite make out but that sounded far too much like the same things she had whispered earlier into her ear.

Sofía realized she was squeezing her thighs without noticing. She also realized she had gotten wet again. She turned the TV volume up a couple of notches. She kept staring at the screen without seeing anything.

***

When Valentina came back into the living room, her hair was slightly disheveled and she smelled of perfume mixed with something else —sweat, sex, semen—. Sofía tried to look her in the eyes and couldn’t quite hold it. Valentina stopped beside the armchair where Sofía was sitting, took her chin gently, and made her raise her face. She gave her a brief kiss on the mouth, without anyone from the kitchen being able to see it.

Sofía didn’t respond. She felt Valentina’s tongue brush her lips once, leaving a trace of someone else’s flavor, salty, not hers.

—I’m going to warm up dinner —Valentina said, letting her go as if nothing had happened.

And she went into the kitchen.

***

Dinner was normal. Her parents arrived shortly after and the conversation followed its usual course: work, weekend plans, the approaching heat. Valentina chatted and laughed as always, without the slightest crack. Sofía ate slowly and answered when asked with short phrases that didn’t invite follow-up.

When no one was looking, Valentina would rest her eyes on her. Just for a second, an instant nobody else would have noticed. Enough.

Sofía lowered her gaze to her plate.

***

That night, before sleeping, Sofía undressed in front of the mirror on her bedroom door. She looked at the hickeys Valentina had left on her breasts: three pink marks that would turn purple in a couple of days. She touched them with the tips of her fingers, first carefully and then with more pressure, checking the lingering sensation. She accidentally pinched a nipple and felt a hot stab that went straight down to her pussy.

She looked herself in the eyes in the mirror for a long moment.

What now?

She slid her hand down her belly, very slowly, until she found herself between her legs. She was still wet. She ran two fingers over her clit and muffled a moan by pressing her lips together. She closed her eyes and saw Valentina’s face between her legs, the pink tongue working her, the low voice telling her to come for me. She rubbed faster, bracing her other hand against the mirror so she wouldn’t lose her balance, and within a few seconds she came again, biting her lip to make no noise, her legs trembling.

She stayed like that for a moment, her forehead pressed to the mirror, breathing hard.

She found no answer. She put on her pajamas, turned off the light, and lay on her back in the dark.

It took her quite a while to fall asleep.