I Discovered My Wife Seducing My Sister

I got home earlier than expected that Thursday. A meeting was canceled at the last minute and I was able to leave almost two hours early, so I stopped at the corner kiosk to buy beers and came home thinking about the match that was starting in half an hour.

As I was putting the key in the door, I heard laughter from upstairs. I recognized it without even thinking: Lucía’s and my sister Paula’s, mixed together in that similar register they had when they were together and wasting time in the best possible way.

“I’m home!” I shouted from the hall.

“We’re in the room!” Lucía called back.

I went up the first few steps, stuck my head around the corner, and immediately understood that I was going to be in the way for quite a while. The room was a chaos of clothes: skirts, blouses, belts, and shoes covered the bed, the chair, and part of the floor. The two of them were in their underwear in the middle of the mess: Paula in a dark lace set I’d only seen a few times, her tits pressed against the cups and her nipples showing through the fabric; Lucía in her usual black bralette and a skin-colored thong that was very familiar to me, the one that disappeared between her ass cheeks and left her ass on display.

And my work shirt, which I had left folded on the chair when I arrived. Lucía was wearing it, open, leaving her cunt barely covered by the pale cotton.

“I see,” I said from the doorway. “Outfit hunt.”

“Bingo!” Paula said with a smile. “But you missed your chance to vote.”

“I never complain about finding two beautiful women in my room.”

Lucía threw a pillow at me. I dodged it in time, told them I was going downstairs, and collapsed on the couch with the first beer. I’d long since learned those clothing sessions could last for hours. I disappeared and turned on the game.

Paula and I are a year apart. We grew up with the same friends, shared things for many years, and when I started dating Lucía, Paula was the one who spent the most time getting to know her. They were very alike in character, in tastes, in the way they laughed. It didn’t surprise me that over time they became more friends with each other than with me.

What I didn’t expect was this.

***

More than an hour and a half passed. The match was in the second half when I remembered to ask what they wanted for dinner. I turned off the TV and started upstairs.

The bedroom door was ajar, as I’d left it. I raised my hand to push it open and stopped.

Paula was standing in front of the full-length mirror, with her back to the door. She was wearing a different set from the one she had on when I went downstairs: something simpler, dark lace, outlining the shape of her hips with a precision that was hard to ignore. My sister had always had that kind of body that attracted looks without trying, something I’d learned not to notice over the years. That night the effort was useless: the long legs, the upturned ass straining the thong fabric, the tits rising and falling with each breath.

Lucía was behind her.

She was still wearing my shirt. And underneath, only the thong.

It took me a few seconds to process the image. Then I understood, from the way the two of them moved, that what was happening was not new. There was a familiarity in every gesture that cannot be improvised.

Lucía swept Paula’s dark hair to one side, exposing her neck, and pressed her lips there. Slowly, unhurriedly, she stuck out her tongue to lick her skin from her collarbone to her ear. Paula tilted her head the other way to make it easier for her: an automatic gesture, without thinking, the gesture of someone who already knows that touch.

Paula closed her eyes in the mirror and parted her lips.

Lucía slipped one strap of the bra down and let it slide along her arm. Her lips followed the bare shoulder, sucking her skin, leaving red marks. She finished pulling the bra down to her waist and freed her tits, those tits of my sister’s that I hadn’t looked at twice in years. Her nipples had gone hard. Lucía grabbed them from behind, one in each hand, and pinched them slowly, tugging them, twisting them between thumb and forefinger. Paula let out a short moan and arched her back against my wife’s body.

The other hand flattened over my sister’s stomach and slid downward without hurry. When it reached her underwear, Paula exhaled soundlessly and pushed her hips forward. She parted her feet just enough. Lucía’s fingers slipped beneath the elastic and found her cunt. I saw the movement in the reflection: two fingers sinking in slowly, going in and out, shining when they came back out. Paula bit her lip and started moving her hips in the same rhythm as Lucía’s hand.

I didn’t move. I could feel my cock hardening against my pants.

How long had they been like this? Weeks? Months?

Lucía was murmuring something in her ear. I couldn’t hear the words, only see the soft movement of her lips and how Paula answered with little contractions of her body, with short gasps that escaped her each time the fingers went deeper. They looked at each other in the mirror, eye to eye, with that kind of look you don’t learn in an afternoon.

“You’re soaking,” Lucía said softly, just loud enough for me to hear. “Look at you.”

She pulled her hand out and showed it to her: the fingers were shining, dripping. Then Lucía herself put them in her mouth and sucked them slowly, with her eyes locked on Paula’s reflection.

Paula turned toward her. They kissed on the mouth with the familiarity of people who already know every detail: lips that already know other lips, hands that already know where to go. I saw their tongues intertwining outside their mouths before sinking back in. I saw Paula take Lucía’s face in her hands and pull her even closer, bite her lower lip, yank her shirt open to grab her tits with both hands and suck them one by one, kneeling for a moment to lick her nipples before standing back up.

Then they broke apart.

Paula pulled her underwear down to her thighs without saying anything, took it off, and lay back on the bed with her knees bent and her arms at her sides. She didn’t cover herself. Her cunt was shaved, swollen, glossy. She opened her legs without a trace of shame. Lucía knelt in front of her between her thighs.

I shouldn’t be watching this.

But I didn’t leave.

What came next was slow and deliberate. Lucía ran her tongue from her ass to her clit in one long stroke, licking all of her. Paula let out a moan that she swallowed halfway. Lucía settled in with her mouth pressed to her cunt and started sucking her clit with the kind of skill that was painfully familiar to me: the rhythm, the angles, the exact moment she changed pressure. Her tongue went in, out, circled her clit in loops, pinched it between her lips. She slipped in two fingers and started moving them fast, curling them inward, searching for the right spot while she kept sucking.

Paula didn’t last long. She grabbed a piece of clothing from the bed and shoved it in her mouth to keep quiet, held Lucía’s head with both hands, and pushed her face against her cunt. She came silently, her legs closing around my wife’s head, her body tightening all at once and then giving way, her thighs trembling, her stomach contracting in spasms.

When she finished, Lucía sat up and ran a hand over her face, wiping the shine from her chin with the back of her hand.

“That was quick,” she said.

“I was really horny,” Paula answered, still not moving, her legs still open and her cunt still throbbing. “Keep that shirt, don’t wash it.”

“It’s not the shirt, Paula. You just really like the way I touch you, that’s all.”

“I know. But keep it anyway.”

There was a pause. Paula exhaled and stared at the ceiling.

“Tonight ask your husband to do it. Tell him you want him to lick you from behind and stick two fingers in at the same time. I’ve been fantasizing about that for months and I haven’t dared ask Marcelo.”

“Why don’t you ask him yourself?”

“Because I’m embarrassed. And because if it works out well, I want you to tell me about it.”

“Get dressed,” Lucía said, laughing softly. “We’ve been up here way too long.”

I went downstairs before she heard footsteps in the hallway. I sank into the couch, turned on the TV without volume, opened a beer I never got around to drinking. I was somewhere else entirely, with my cock hard against my pants and the image of my sister spreading her legs burned into the inside of my eyelids.

***

Paula left forty minutes later. We saw her out at the door. I noticed she was carrying a canvas bag with clothes she hadn’t brought with her. I thought I recognized the collar of my shirt peeking out between the folds.

We had dinner like any other night. Lucía reheated pasta from the day before. We talked about a movie she wanted to see, about a doctor’s appointment I had to make, about anything. I filled our glasses twice. I nodded at the right moments.

We went upstairs ten minutes before midnight.

Lucía was walking ahead of me on the stairs, in a short T-shirt and the skin-colored thong. The way she climbed those steps in that outfit — her ass moving, the fabric disappearing between her cheeks — made something in me decide before I had even thought it through.

“That thong,” I said. “That thong always drives me crazy.”

She laughed without turning around.

“I’ve had it for three years.”

“I know. That’s why.”

We got to the bedroom. She took off her shirt and turned to me, tits out, nipples already hard. I stepped closer.

“Tonight I want to go down on you,” I said. “And I want to lick you from behind and put two fingers in at the same time.”

Lucía froze.

She turned slowly and looked me in the eyes for a few seconds longer than usual, with that expression of someone evaluating whether what they just heard is a coincidence or not.

I held her gaze without blinking.

“Where did you get that from?” she asked carefully.

“From being turned on,” I said. “From having you around all day in that underwear. Is there a problem?”

Another second of silence. She seemed to be calculating something.

“None,” she replied, and the tension vanished from her face. “No problem at all.”

I tore the thong off her sides. She laughed in surprise and didn’t protest. I pushed her onto the bed, face down first, and lifted her hips. Her ass pointed toward me, legs open, cunt already shining between her thighs. I ran my tongue from her clit to her ass in one slow stroke, tasting all of her, just as I had seen done a little earlier. Lucía moaned into the pillow and arched her back to offer herself more.

I buried my tongue in her cunt, licked her lips one by one, sucked her without hurry. Then I moved up and ran my tongue behind her, around her ass, pressing the muscle with the tip of my tongue until Lucía let out a sharper moan than usual. At the same time I slid two fingers into her cunt, curled upward, and started moving them fast while I kept licking her ass. Lucía buried her face in the pillow and started crying out muffled, her fingers clutching the sheets.

“Like that,” she gasped. “Like that, don’t stop.”

She came with her hips pushing against my face, her cunt tightening around my fingers, so hard I could feel the pulse beating inside her. I flipped her over before she had fully come down. I unzipped my pants and drove my cock into her in one thrust. She was so wet there was no resistance. I grabbed her nipples with both hands and squeezed them while I fucked her deep, thrusting against the back of her, looking at her face twisted by pleasure.

“Look at me,” I said.

She opened her eyes and looked at me. I fucked harder. Her tits shook with every thrust. She dug her nails into my back, squeezed me with her legs hooked behind me, begged for more with her hips.

“Cum inside me,” she panted. “Cum inside me.”

I kept hammering her until she came again, screaming against my shoulder, and then I let go. I came deep, emptying myself inside her with two, three final thrusts that left her trembling beneath me. I felt the semen slipping out around the sides of my cock while I kept moving slowly, milking her.

We stayed silent afterward. The ceiling, the darkness, her breathing gradually settling. Semen trickled down between her thighs onto the sheet.

“Are you in my head?” she murmured against my shoulder.

“I just pay attention,” I said.

She fell asleep quickly. I stayed awake much longer than I would have liked.

How long had they been like that? Who started it?

Was I going to tell her I’d seen?

Or was I going to leave things exactly as they were and see where it led?

The ceiling had no answers. Lucía’s body rose and fell beside me with her calm breathing. Outside, the street was silent.

I still didn’t know what I was going to do. But I did know something had changed that night between us, even if she didn’t know it. And that Paula had an outstanding debt she might never collect.

Or maybe she would.

I closed my eyes and waited for sleep.