[MF] [WG] [Cheating] Her Sister Knows All About It

*Your first time heading home to her parents’ for the festival season since you moved in together. Who will dare to say anything about what you’ve done to her?*

I woke up next to Olivia, my girlfriend of two years. We were too young to get married, but as we couldn’t keep our hands off each other for 10 seconds, we’d moved in together about nine months ago. It was spring then- now we were staring down the barrel of winter. Usually that would depress me, but these days I wanted nothing more than to be a homebody with my darling girlfriend in our lovely cosy warm house. We had a nice TV and we cooked well every night. It was heaven!

Of course our lifestyle had started to show up on Oli’s hips, and everywhere else in fact. While I maintained my figure through sports with the boys and biking for every errand and commute, Oli had settled into a work-from-home job, a hardcore gaming habit and a cornucopia of delicious foods as a matter of course. I was admiring her soft, feminine form draped across our bed, so beautiful in the morning light. I got up quietly to prepare my love’s morning feast of pancakes and bacon. She woke up to the scent of hot chocolate and the delicious fried plate, served in bed as usual, balanced on her pudgy thighs.

After she polished it off I began to play with her hair and talk about today’s mission impossible.

“So, off home for good old Saint Hinterlaas Day, that wonderful November festival for all the family. This time with a plus one. You looking forward to it honey?”

“Oh, I don’t know…” she was still tired, the hot chocolate yet to work its magic. She was also still chewing a bit of pancake. “We went to your folks for summer, it’s been pretty much a year since they saw me. It might be awkward.”

I cuddled in as she set her plate aside on the cabinet. She shuffled her naked leg round to wrap around my butt. I hugged her warmly and she rested her head to the side, towards mine. “It’ll be okay. They’re still your family Ol. They’ll love you whatever you do… and I hope they at least like me too.”

“Oh, but you know what I mean… I’m so different…” she slid her podgy hands under her thick belly roll, hanging over her red and white lace panties. “I’ve got all this heft thanks to you, and they’re going to notice, whatever I wear.”

“hmmmm….” I licked my lips and slid in to lock my body to hers, feeling all the softness we’d been working so hard on. I blew a raspberry on her fat tummy. “It’s an excellent addition…”

We began to play some more, I slid down between her thighs as her reply came, a giggle and a comment: “And my sister… such a bitch, since her husband left her she’s been so judgy of other women…”

My reply came from between her legs as I pressed my mouth onto the lace of her panty and searched for the telltale damp of turnon, “that’s what happens when bitches ain’t gettin’ their pussy ate…”

Her reply came quickly, she moaned then slapped the top of my head playfully, “oh you are awful mister. The things I let you get away with around me!”

A few seconds later the panties were off, then I came up to make out with my chubby darling. She licked her pussy juices off my lips then grabbed my cock from my pyjama bottoms and worked it to attention- again, this took seconds. Within a minute we were on the bed fucking like animals, as usual. I had her pinned down and she was shrieking like a small dog, her belly and breasts wobbling back and forth like crazy. This went on for a couple minutes- heaven, as ever- then she tried getting on top. She’s not as fit as she was nine months ago- she can only ride for maybe two or three minutes before wheezing like an old train. She gets off coated in sweat and I push my cock back inside as she lies on the bed- quickly checking the time on her phone as I fuck her prone- then we returned to the missionary position as she reminded me “we really need to get going…” I push my muscular shoulders in and whisper in her ear less of a question and more of a promise, “I’m gonna cum inside you…” Of course this is nothing new and we’re all up on our BC. It’s no less hot as I lock eyes with her, tense my abs and shoot my load deep into her flab-coated womb. I collapse on top of her and we sweat for a few minutes, panting messes both.

She kissed my cheek and pushes me aside to finally rise from bed. She picks up a clean pair of sensible grey panties and pulls them up over her fat thighs, my load still dripping into them. She winks at me and reminds me it’d be hot if she was walking round her parents’ place with my cum inside her. I don’t argue and watch as my overfed girlfriend dons the rest of her outfit. Her latterly formed back fat folds as she clips a giant bra into place and then struggles with a tight formal dress. I grope her globular arse as I help her zip it. So soft, I can hardly remember the toned gymgoing girl I first met at the hiking club two years back.

Finally downstairs, I make some tea and carby snacks for the road as she does her hair and make-up. She plods down our tight stairs- it’s a very small, old house squeezed into the city, all we could afford- making it creak and going sideways so she doesn’t stumble. She was wearing a gorgeous, smart knee length sweater dress, black tights and sensible heels. There was definitely a bit of a VBO, which shifted which knee it rested on as she made her way slowly down the stairs. I passed her another hot chocolate and some toast, for the road. The rest was packed in a nice big lunchbox for us to share on the route.

It was cold outside, but warm inside the large SUV we had purchased for her to drive a few months ago. I had no car myself- but it was clear to me that an essential part of a fat girl lifestyle was a nice big motor with room for growth, to go absolutely everywhere, from the pizza shop one block over to the city centre. No walking allowed! I struggled along with my bike, dodging drivers, working up mad leg muscles, getting sweaty. But it’s very much a “my hands look like this, so hers can look like this” kind of situation. All that effort on the bike pays off in extra fat all over my lover’s thick arms, thighs, back… hnnnggg, you get the picture.

Funny thing is we weren’t even driving to her parents. Along with seemingly the whole of Dausburf-Honitaan, the small continental city we’ve set up nest in, we were heading for the railway station for old Saint Hinty’s. We parked up the SUV in the tiny bays at the station car park- clearly designed for a more distinctly European style of car. I dropped Ol at the station entrance so she wouldn’t have to walk round, and she grabbed our tickets and a coffee- and a doughnut- while I squeezed out of the car and then struggled with our cases and the coolbox.

The station itself is designed for people of a bygone age- that is, rather slimmer. Some of the corridors, Ol can almost touch both sides these days. There are a few tuts from passengers eager to get home to mum’s for the holli, annoyed at being stuck behind a woman not used to walking fast these days.

Thankfully when we finally get on the train- me struggling with all the cases, did I mention?- they’re a lot more modern than Dausburf’s old station. We recently got a whole new round of investment in our railways and it all went on making the trains swish, modern, roomy. We even get a nice big seat and table setup to ourselves.

We’re not actually going that far- her parents are only a couple towns over on this line, though the train will go halfway to Russia by all accounts. It’s still a nice train though, really comfy and modern with great views. Snow capped peaks, shimmering lakes, bird sanctuaries, cute little country villages- they don’t have a station, of course, so you have to wonder if they like us passing by as much as we like to gawp at them. The best bit though is this train even had a buffet car, and Oli soon worked out that she could place an order right from a small screen at our table- and she could send mr simpy mcsimp here to go and get it for her! I kid, of course, I loooove that she’s so lazy and I think I even like it when she’s exploiting me a bit.

About two hours later, Ol’s looking well stuffed between all the snacks I brought in the cooler and the extras we’d picked up from the buffet car. I help slide her distended body out of the booth. She looks close to sleeping, so it’s a good thing her sister’s come to pick us up at the station. It would be dangerous if she was to drive in this dozy state!

Ol’s sister Joanne meets us on the platform of Hankbol-Hoffenklassen. She only lives the next town over so she’s driven home instead of getting the train cross country like us. Clearly she’s already reacquainted herself with the sweet shop on the high street she developed a love for as a kid, cos she’s grabbed three of her favourite snack cakes. She goes to hand them to us then she notices Ol’s heavy layer of fat around her middle, pushing her dress to its limits already. She hesitates for a second before giving it to us anyway- Ol’s too tired to notice but Jo shoots me a look as they embrace. Jo’s looking slim, she works as an artist for a local youth project and has a hipster boyfriend, but it’s not too serious since her old career and marriage went tits up a while back, when Ol and I were only just getting to know each other. She has curly hair in a bob and drives a smaller car than Ol’s used to. Oli squeezes into the back with a few puffs and complaints- “I swear they used to make these rustbuckets with a bit more room in em Jo”- and I get in the passenger seat. There’s a few sweet wrappers on the floor, but it’s nowhere near as outrageous as the fast food wrapper mountains I regularly have to fish out of Olivia’s SUV.

The chat is mainly between the two sisters as they head out into the old-style suburbs – up a bit of a hill at the foot of the mountains- towards the old folks’ place. I feel like a right third wheel. It’s all how’s that kid at school doing now and how’s new boyfriend’s dog doing and did I tell you I got a promotion to chief linkedin manager and whatever. I just admire the scenery and practice some polite phrases to say to mum and dad in my head. Their language is my second language, so I have to make sure I have my story straight.

But I needn’t have worried. Soon as we were in the door it was all smiles- as usual a bit of a struggle for hefty Olivia and a lot of a struggle for me as her dad laughs at me carrying all the cases – “women, eh, son! They keep us wrapped around their pinky fingers! Ah, but we love em for it!” I love his bodily laugh, I can see where Oli got her humour from.

We put our things in Oli’s old room upstairs and I give her an encouraging smile. “It’s going well, isn’t it?” I say.

“Yes, you know my mother even seems to think I look great and she’s really happy to hear we’re getting on so well.”

“They’re happy for you Ol.” I give her a quick peck and we skip back down. Mum’s already got dinner ready.

First course, second, dessert, appetisers, and the champagne is flowing. It’s not a true Saint H’s Day if the whole family aren’t too drunk to drive and stuffed to the gills. The party games come out later- some charades where Dad makes some sexual comments about how “your old mum has a few tricks in her yet girls!” and I quickly divert my gaze and stifle a chortle as the girls go in unison: “Daaad!!!” Oli’s charades are almost all about food, and I can see mum, dad and Jo all taking some extra glances at the full form that lies underneath her warm knitted dress. The game falls apart after a while; Dad’s watching the match with an extra beer, mum’s washing up and Ol’s helping by polishing off some canapes at the worktop. Jo’s hanging round, polishing off some rum and looking for trouble.

“You’re looking verrrry smart these days, young man. I can see that Oli’s been sorting out that scruffy old wardrobe of yours.”

I smiled, a little pride being the least of my sins. “Yep, she’s a great dresser.” I should know, I get to watch her flabby arse pull up jeans every morning. God. Jesus. Heaven. I’m looking straight at the definition of her arse now in that comfy dress. Is that the line of her panty I can see across the fat cheek? I wonder if my cum is still lining her labia.

Jo’s let her hair down a little now and swishes the rum around in the glass. She places a hand on my shoulder and smooths down the collar. “And these arms, I dare say someone’s been working out?”

“Eh, not as much as I’d like. You know, I look after myself. Keep active. Football with the boys a couple times a week, maybe hit the climbing wall.”

Mum shouted over above the music playing on the TV as a goal was scored- “Ol’s just gonna help me with a computer problem upstairs a minute. You know good she is with ’em. Has everyone had enough to eat down here?”

“Absolutely stuffed!” we all shouted back. Ol didn’t shout, her mouth was still full. She waddled off up the stairs- considerably roomier than ours at home- with her mother.

“listen,” Jo purred in my ear. “I don’t think our silly old mama has noticed yet but don’t think I don’t know what you and Oli are getting up to in that love shack of yours. My old husband was just the same.”

I stiffened up- and not in a good way. “What are you talking about?” On the defensive.

Jo placed a hand on the small of my back and led me out of the kitchen to the back yard. We strolled across the deck and down towards the garden gate. The view of the mountain was quite impressive.

“I can see how every time we see her she’s gotten fatter, podgier, lazier, heavier… my husband wanted the same from me. He wanted a fat lard arse to sink his cock into every ten minutes, and when I wouldn’t give that to him we split. It looks like my little sister is far more pliable- expandable, you might say, than I ever was. Is that right?”

Despite my dirtiest secrets being laid out for all to hear I was stiffening in what would normally be the good way. The use of language- podgier, heavier, expanding… to think about how fat I’d got Oli up to compared to skinny Jo, two years her elder, it turned me on in the most depraved way.

“I’m gonna tell mum all about it, I think. Would you like that?” She glimpsed down at my jeans getting tight. “Something tells me you would, despite all the criticisim you’d get from her. She’d be down there like a flash to “save” her darling little Ollykins. What would you do about it?”

I was starting to sweat. “Let’s… let’s walk.” I needed to walk this erroneous erection off, pronto. I couldn’t let her get to me.

She pranced on ahead down the garden path, knocking open the old wooden gate with her cute, round little yoga butt. She was wearing a pencil skirt but displayed a remarkable level of flexibility for it. She walked on ahead leading me to a small shack further up into the mountain. She leaned against the one solid stone wall it had. “Does Oli even know exactly what you’re into? Like I said, I know because my husband used to like to whisper in my ear that he wanted me to put on 10, 20, 50 stone, to be the heaviest woman he’d ever fucked, to make me unrecognisable to my family. he was a sick bastard. You know he said I should stop going to yoga? He even tried to get me to hang out with his fat ex girlfriend, get some better habits he said, like hanging round the ice cream parlour all day. Getting F- A- T of course.”

Damn. Sounds like we might get along. Though his methods sound a bit rotten, I at least had to respect his honesty with her.

“She doesn’t know, does she?” She took my lack of response as a negative. “She just thinks she’s a comfy homemaker, settling into adulthood and putting on the timber that comes with her IT desk job, her doting boyfriend and her comfy slippers. She doesn’t realise that the new love for carbs she’s developed is partially your engineering, doe she? You dirty bastard. I bet you told her all the weight is a side effect of the birth control.”

Fuck, she was really digging into my psyche. I got a bit closer to her, pushing her through the wooden door in case anyone was listening from the house. The hut was a small box, the girls used to play there when they were small, pretending to be shepherds, adventurers, cowboys, you name it. There was a table and a chair, that was about it. “Listen, Jo, what the fuck do you want from me?”

“Welll…” she pushed me off a bit, I guess I had been getting in her face. Her fault for getting into my head. “I do want some money, you know. The yoga teaching isn’t quite paying all the bills now I’m flying solo.”

“What about your boyfriend…”

“Oh now,” she gives me a devilish look with those big eyes of hers. “He’s hardly going to make any money for me, is he? No, we’re not as loved up as you two nesting birds, we’re far off that kind of stage. It’s veeery casual.” The rum was still making its way through her system, I could see. And the champagne in mine, to tell the truth. “just give me a few wads, won’t you? You don’t want me to tell mummy all about what makes this big heavy beast…” she placed a hand on the waistband of my jeans, “…what makes this monster growl when little Olly’s thighs are chafing with all the extra saturated fat in her diet?”

“Fine,” I grumbled, and struggled to avoid touching her- to avoid sparks of static, we were rubbing up that close- as I got round her arm and reached for my pocket to grab my wallet. I peeled off a few fifty euro notes and stuffed it into her bra. “That’s enough now Joanne.”

“No, that’s not enough.” She pulled my waist in closer. My cock, straining at its haunches, brushed the inside of her perfect yoga instructor hips. “What will your darling wife say if you’ve been blowing all the housekeeping money on a little whore?”

“she’s not my wife…” I groaned but I could already feel things changing. The eternal beast which locked me to this family was being woken, and it was looking at the wrong woman.

“are you sure about that… the way you two go around these days you may as well be joined at the hip… ” Agh, she pushes all the buttons. Two years older but so much slimmer. Like… like Oli two years ago when we first met… on that hike in the Burg D’Armes. But if she’d stayed so fit for four years, not set up a nest with me and collapsed into layers of plodge.

“look, what else do you want?” My last chance to avert the situation.

She stops the tight grab on my waist and backs away, hitting the wall with her back and putting a leg up on the little table. She looks me straight in the eye. “I want you.”

*fuck*

I drop the jeans a little. It’s cold out so I don’t expose my arse. She unzips her pencil skirt, uses it like a blanket as she spreads her legs using the kids table as a base. My cock and balls are pressed riskily amongst the zip of my jeans. She’s wearing a black thong across her tight, shaved cunt. Her hips are so prominent, bones forming a bikini bridge and her mound of venus dropping back before her slim stomach shows up. Almost like the inverse of Oli’s fat fupa and overhanging young stomach. My treacherous cock can’t wait. The beast is out. I pull the thong slightly aside.

Grabbing those bony hips and forcing myself inside her like an animal- although I slip in, she’s well ready- I realise I had forgotten what a skinny woman feels like. I am able to pretty much carry her entire slim body weight with only a bit of help from the wall. I drive my cock in like a power tool, I’m not really interested in her pleasure as much as my own, despite my entire lifestyle all riding on my ability to please her. She is just so unabashedly sexy. Not that Oli isn’t, not at all. But like I said, it was almost like a new type of sex for me after so long fucking my increasingly obese almost-wife whose name was on the wall of this shack from childhood- “Oli was here”. And I liked it that way. And I liked it this way, too.

But it wasn’t really okay.

My balls of course didn’t give a shit if it was okay or not. They gave, instead, one thick rope of cum, as heavy as that I had blasted into Olivia’s sensible grey silk panties this morning. It drives into the womb of this sexy yoga teacher with curly hair. I have no fucking clue if she’s on birth control, because who the fuck talks about that shit with their girlfriend’s sister? All I could think was to remember the tight, almost cold feeling of bony hips, round bottom, pert tits and light legs the next time I fuck my fat girlfriend. The memory alone would drive a thousand before-and-after style wank fantasies, even if I was actually remembering her fit sister, and not the girl I was fucking after a good hike two years ago.

As she pulls her thong back into place and straightens up her bob, I help her back into the skirt. There’s some crayon marks on it. We’ve smudged another message- “Jo was here” from some forgotten game- and it’s left a mark. My cum also drips around the black thong and spots her skirt from behind. “It’s fine,” she smiles at me, “We’ll say it was some mountain dew.” We make our way slowly back down to the garden, in through the gate and into the back of the kitchen again. Everything’s spotless and the three are sitting on the couch with a big bag of chips and a film on. We were panting a bit but I don’t think they noticed.

“Where’ve you been?” shouts their mother as she quickly spins round, then back so she doesn’t miss the action.

“Ah just for a hike. Showing the new one the sights.” said Joanne. She brushed some more dust off her blouse- she had caught her breath already before me, as I mentioned, super fit yoga teacher.

“Ah, glad you went without me. I’m not really the kind of girl for hiking.” laughed Oli. I could swear she even tapped her belly a bit, but no one else seemed to notice.

“That’s strange,” says her mum, turning slightly to look at her taking up all the room on the sofa next to her. “You used to walk in the hills with Jo all the time.”

Dad coughs, shushes us and turns the volume up.

I pull up a chair behind the sofa and pretend to pay attention to the film. But of course my thoughts are racing, even more so when Jo leaves the room to go upstairs and head for the bathroom. I imagine her getting out all of my cum, planning god knows what next. She knows now she has me wrapped around her pinky finger, and she can have me anytime she likes. That’s a bad situation, obviously, but is it really?

I just hope I have enough steam to please them both… the fat computer tech sister and the fit yoga lover sister. We’re going home in the morning, but it’ll be a full family meetup at the old folks again soon enough, and the whole charade will start all over again…

Before we leave in the morning she even lets us know that she’ll be in Dausburf for a few days next month to see a master yogi guru, in an effort to flesh out her fledgling business a bit more. And would we mind if we put her up in our spare room? Oli’s all smiles, “of course! Anything for my big sis to get her business going! The boy here will cook us the best meals, like he always does for me, isn’t that right?”

All i can say is yes, but as Ol struggles into Jo’s little car, the big sister whispers to me: “I’ll wear my cutest, most sensible panties… maybe even overeat a little before I come. I know how much you like that mister.”

And of course, the journey home was longer than ever. For Oli, because there was just so much time to eat so much food. For me, because I had big problems to worry about…

Source: reddit.com/r/sexystories/comments/k8x4hk/mf_wg_cheating_her_sister_knows_all_about_it