The Heat My Pregnant Sister-in-Law Aroused in Me

The news landed right in the middle of New Year’s Eve dinner, amid toasts and half-finished plates. Marisol, Mateo’s older sister, was expecting twins: a boy and a girl. She was twenty-one weeks pregnant, and her belly had only just begun to round beneath her dress. The family erupted in applause, someone remembered there had already been other sets of twins on the grandparents’ side, and at the far end of the sofa Carolina felt her mouth go dry.

—Baby —she whispered, leaning in close to Mateo’s ear—, then there’s a real chance that if you knock me up, you’ll leave me pregnant with twins.

Mateo raised an eyebrow, amused.

—Genetically, yes. There’s a family history. Why is your face lighting up like that?

—Because ever since I started my internship in the maternity ward, I can’t stand how horny I am —she confessed, biting her lip—. Yesterday I had to take in a woman with a twin pregnancy. False alarm, she wasn’t in labor yet, but her belly was huge, hard as a rock. And the groans from the contractions left me soaking wet. I can’t stop imagining your sister like that.

—You’re insane, Carolina. —Mateo gave a low laugh, but his hand tightened on her thigh—. And yet I love how turned on you are.

—You’d better keep thinking that. According to my own stats, if you get me pregnant I’m going to get a hell of a lot worse.

He didn’t answer. He swallowed and looked to the other side of the room, where Marisol was stroking her belly while Gonzalo, her husband, tucked a pillow behind her back. They should have felt awkward talking about his sister. Instead, his girlfriend’s overflowing arousal dragged him into new, slippery territory neither of them wanted to leave.

***

A week later, Marisol asked Carolina for a favor. Gonzalo was going out of town and didn’t want her driving alone to her checkup.

—Could you drive me? You’re heading to the hospital anyway.

—Of course, sis. What time is the appointment, and with whom?

—At three, with Dr. Belén. They referred me to her because of the risk with a twin pregnancy and, I’ll admit, I’m pretty nervous.

—I know her, I spent a month in her clinic. She’s excellent. —Carolina hesitated only a second—. In fact, if you want, I’ll go with you to the exam. I start at two, but I can slip out for a bit.

—Would you do that for me?

—For you and my nephews, anything.

On the day of the appointment, standing beside the exam table, Carolina watched her sister-in-law bare from the waist up while the doctor spread the gel and moved the transducer over her. The taut belly, the swollen breasts, the nipples darkened by pregnancy. She thought, almost against her will, that her maternity rotation lasted six months and that it was perfectly likely she’d be there when Marisol gave birth. The idea ignited a dull heat between her legs that she had to hide by crossing her arms.

That night she told Mateo everything, leaving out not a single detail. He listened with increasingly heavy breathing, and they ended up tangled in the sheets until dawn.

***

Two months passed. Carolina witnessed an astonishing number of births, and each one drove her temperature up to levels she would never have imagined. Mateo, for his part, did nothing but benefit from a girlfriend who was wet twenty-four hours a day. In four years together they had never had as many orgasms as they did in those weeks. And at the same time, they watched Marisol swell more and more with every family visit.

One Saturday afternoon, Mateo had just gotten out of the shower. Carolina was due any minute to go to the movies and, hopefully, afterward to a hotel. When the doorbell rang, he assumed she’d arrived early and opened the door half dressed.

It wasn’t Carolina. In the foreground, taking up the entire doorway, was his sister’s enormous belly, nearly thirty weeks along. Behind her came Gonzalo, loaded down with suitcases, a maternity pillow, and a backpack.

—Hi, sis. And this? —he asked, bewildered.

—Mum didn’t tell you? Gonzalo’s leaving for a month for work and he doesn’t want me staying alone. I’m moving in here until he gets back.

—Nobody told me, but I’m glad. I’ll get to watch you grow in real time. —He burst out laughing.

—Shut up, idiot. I’m already huge and I still have ten weeks to go. The doula says that even if they’re twins, I might be able to carry them to term.

—I hope so. The longer they stay in, the better for them.

While Mateo helped Gonzalo with the suitcases, Marisol made her way slowly down the hallway, swaying from side to side like a duck under the weight she was carrying in front. Mateo couldn’t help staring at her a second too long.

***

When Carolina arrived that afternoon, she wasn’t expecting the scene she found when she walked in. Marisol was sitting on the couch with her enormous belly uncovered, and Mateo’s hands were moving over the tight skin under the pretext of searching for kicks. The image hit her full on. She felt the heat settle at once between her thighs, her underwear wet almost instantly.

—Sis! What a miracle! —she said, pretending surprise—. How are those babies doing?

—Hi, Caro! Wonderful, growing. I feel like I’m going to burst any minute.

—But you still have about ten weeks left, right?

—Tomorrow I’m exactly thirty weeks.

Just then Marisol let out a muffled groan and pressed a hand beneath her ribs. The belly tightened sharply under Mateo’s fingers, and Carolina felt her own lips throb even more, if that was possible.

—Are you okay? —Mateo asked, hiding the arousal that groan had stirred in him behind genuine concern.

—Yes, it’s just that your nephews are getting stronger every day and there’s no room left. When they stretch, it hurts. —She took a deep breath and smiled—. Want to feel them kick, Caro?

—Yes! —she answered without hiding a thing.

She sat beside her and placed both hands on the taut belly. She ran them over it in full, under the excuse of tracking the twins’ movements, feeling the firmness of the stretched skin, the protruding navel, the hot pulse of life packed tightly inside. It was the first time she’d touched a belly like that without latex gloves and a clinical gown in between. Without having to behave like a professional. Her heart hammered in her ears.

Mateo, on the other side, had his jaw clenched. They traded a look over Marisol’s stomach, and that was enough for both of them to understand: neither could take it anymore.

***

Carolina jumped to her feet and tugged her boyfriend by the hand toward the door, using the excuse that she didn’t want to miss the show.

—Did you buy the tickets? What are we even watching? We didn’t even agree on anything —Mateo complained as soon as they hit the street.

—Fuck the movie —she cut him off, shoving him against the car—. I need you to fuck me right now. It’s the first time I’ve touched a belly without having to measure every move. And what a belly, Mateo. Your sister is getting huge and I can’t handle this horniness. Let’s go to a hotel. Please.

They made the whole trip with Carolina’s hand clenched around the hard bulge over Mateo’s pants. By the time they reached the hotel, she was leaking between her legs and his balls ached from being so tight.

They closed the door and nearly ripped each other’s clothes off. Carolina shoved him onto the bed and climbed on top, guiding him inside her in one single thrust that drew a moan from both of them. She started moving slowly, her nails dug into his chest, her eyes half-lidded.

—I can’t stop imagining her —she panted—. That huge belly, hard, stretched tight. Imagine it was me. Imagine you left me like that.

—Say it again —Mateo growled, grabbing her hips and driving her down onto him.

—Get me pregnant —she moaned, speeding up—. Get me pregnant, give me twins, give me a belly like hers. I want to burst like she does.

They both knew it wasn’t going to happen. Carolina was still protecting herself; she hadn’t stopped taking the pill. No matter how horny she got, she was responsible. But the fantasy worked too well. Every word she let out between moans made Mateo even harder, and he fucked her thinking exactly that, of inflating his girlfriend’s flat belly, of watching her sway just like his sister.

—That’s it —he said through his teeth, flipping her over to pin her beneath him—. Tell me what you want.

—I want —she repeated, opening herself wider, taking him in to the hilt—. I want you to fill me. I want the belly, the twins, everything.

Carolina came first, with a hoarse cry that shook the whole bed, and the contraction dragged Mateo over the edge a second later. He collapsed on top of her in gasps and grunts, forehead slick with sweat, still moving slowly as the last shudder ran through them.

***

They lay there on the damp sheets, their bodies stuck together with sweat, catching their breath. Carolina lazily traced circles on Mateo’s chest.

—That was one of the best —she said, still breathless—. By far.

—Since we discovered this... fetish —he replied, searching for the word—, we haven’t been the same.

She laughed against his neck, with that low, hot laugh he knew by heart.

—There are still ten weeks until Marisol gives birth. —Carolina lifted her head, her eyes shining in a way that made Mateo’s skin prickle—. Ten weeks in which her belly will only keep growing. And if I’m lucky, I’ll be in the room when she has them.

Mateo closed his eyes and let out a groan halfway between warning and surrender.

—You’re going to kill me, girl.

—Not yet —she murmured, sliding her hand downward again—. We’ve paid for the room until midnight.