[MF] How my stepsister [18F] learned that I heard her having loud sex

This is the 3rd part of my story describing my sexual adventures with my stepsister, Katie. For part 1 click [here](https://www.reddit.com/r/gonewildstories/comments/h7krnu/mf_how_i_21m_spied_on_my_stepsisters_18f/), for part 2 click [here](https://www.reddit.com/r/incest/comments/h87omc/bs_i_jerked_off_while_spying_on_my_stepsister_18f/).

Enjoy!

Another month or so had passed. At that point, I had been lusting over Katie for some time. As weeks passed, temperature changed, and we got closer and closer to summer, Katie’s attire had become more and more revealing. To the point that you basically never saw her wearing anything covering her legs or arms. On lucky days, she wore nothing but a pair of tight-as-skin booty shorts and a crop top revealing even more sun-kissed skin.

God, she was gorgeous.

I had always known our parents were liberal, to say the least, when it came to raising us, but, you know, even I was shocked when they didn’t reprymend her at all for what she chose to wear. Being how laid-back they were, I was sure that if they ever found Katie sucking her boyfriend’s cock in our house, they would simply back off and let her swallow in peace.

I was sure Katie was a swallower.

It really seemed like since her 18th birthday she had entered a slutty phase and was truly set on ap ath of expressing herself as sexually active and promiscuous. At least that was what I got from how she carried herself in real life and her social media presence.

God, I had jacked off to her Instagram feed more than once I must say.

There was that one photo taken at the beach where she went with her fiends a couple weeks prior. On it, she had on some kinda high-cut one-piece bathing suit. It was all white and covered barely anything when it came to her butt, and since the pose on the picture was her standing with her back to the camera, slightly bent over, doing that one hair flip trick, where the water coming from her hair created a pretty nifty crescent, you had a perfect view on her excellent ass and plump pussy covered by the wet suit.

More than once had I imagined myself peeling the moist fabric to the side, revealing Katie’s plush, smooth pussy lips, and just shoving my dick inside as far as it would go. Plowing her like a slut right there, in front of her friends and boyfriend. Making her as soaked on the inside as she had been on the outside.

As days passed, sadly, I hadn’t overheard any more sex noises coming from Katie’s room. For the most part, our parents were rather domestic and they rarely left for the night, hindering any possibility for my sister to have Thomas, her nerdy boyfriend, over.

Speaking of Thomas, the more time had passed with him as Katie’s significant other, the more shocked had I become that Katie would choose him as her partner. Don’t get me wrong though, I liked the guy. He was pretty charming and easy to talk to and I had nothing at all against him but…

I guess I was simply jealous? In those self-retrospect instances, I never failed to laugh at myself. What had become of me. I was such a pervert.

Remember the time when I stopped myself from jacking off using my sister’s underwear? Well, that didn’t last long.

I masturbated with her panties either wrapped around my dick or shoved in my face at least couple times a week. I didn’t care if it was sweat or pussy juices but I discovered they were always at least moist when I grabbed them from the laundry bin. After coming, my dick was all shiny and wet-looking and I loved to think it was because her delicious juices covered it. Can you imagine how it would look after I fucked her brains out for real? I bet my cock would quite literally drip.

A few times I had caught myself staring in the bathroom mirror but always quickly turned around. I guess seeing myself with my sister’s drenched underwear covering half of my face was too much of a jab to my pride.

Ah, what pervert had I become.

I wished there was something, anything I could have done to at least see Katie naked again. But, what? Was I supposed to install a camera in her room? I researched extensively how to set that up but, in the end, I was too scared to even try. What if she discovered it? I would be shamed for eternity. No, I wouldn’t risk it. I even contemplated catfishing her and pulling nudes out of her on some dating app, but apparently she had removed everything after getting into a relationship with Thomas.

Was there truly nothing I could do?

Well… About that…

You see, we were pretty chill when it came to being siblings. I could count on the fingers of one hand the number of times we fought in the past. One day, though, my patience couldn’t bear her antics. I can’t even remember exactly what caused the fight. I think she had been loud and obnoxious the whole day and I really had to study because finals were approaching steadily. It was one of those rare occasions when our parents were out of the house and she chose to spend that time being annoying all around.

At the time I speak of, we had been at each others’ throats for over an hour. She had rushed inside my room and yelled at me to chill and stop calling her a child.

Imagine the scene as such, Katie standing, all pissed off, in the doorway to my room and me, sited at my desk, on the opposite side. I can’t really make out what she wore that day but I bet it was nothing more than a pair of skimpy shorts and a tank-top. Something I was used to seeing her in at home.

As such, we argued:

“What the fuck is your problem, can’t you just fucking shut up and go sit in your room for one hour while I fucking try to study for my exams?!” I yelled back, barely containing myself from standing up and rushing to ‘escort’ her out of my room.

“OH MY FUCKING GOD! You have been doing nothing but sitting in your room for the past week. You know they never leave the house.” She talked about our parents.” I did as you asked and haven’t invited anyone over, even though I probably should have. Can’t you chill for just a second and, I dunno, let’s order a pizza or something. Gosh.”

“Just fuck off, please. You don’t get it and you’re being a kid. Leave my room.” She wasn’t too happy at that. I remember her screeching very well.

“I am NOT a fucking kid! Fuck off! You’re such a fucking nerd!” That took me aback a bit, that was basically the first time Katie had ever insulted me to my face like that. I felt myself getting seriously mad.

“I am a nerd?!” I interrupted her. “Have you seen your fucking boyfriend?” Trust me, I know I was an undeniable, exemplary case of a nerd. But there was something about that insult that just struck a nerve. Maybe it was because kids in school used to call me that all the time? Who knows.

Her brows scrunched in surprise, she wasn’t expecting me to go after Thomas. “What the fuck do you mean?? Why are you even bringing him up, what the fuck?”

I knew I was petty for saying what I am about to tell you, but I didn’t care. I was pissed, tired, and not good at arguing. So, I retorted: “Well, maybe if he wasn’t a nerd he wouldn’t come in five minutes when he fucked you last month.” As words left my mouth, her expression dropped in an instant. She stood there frozen with shocked face and slumped shoulders. Some sort of panic-like emotion was clearly settling in in her eyes. “Yep. I heard everything, you know.” I added with venom.

Anger was still boiling in me so I didn’t really care. I sat there, staring at her and waiting for her to respond. She dodged my eyes for the first time after entering my room and responded: “Are you actually serious?” She shifted on her legs. “Fuck, I knew that was a bad idea. This is so fucking embarrassing…” And indeed, there was a scarlet blush quickly covering the entirety of her face.

Starting to feel bad after what I’d said, I raised my eyebrows in worry and quickly stood up. “It’s not a big deal…” I started, taking a slow step closer towards her. “I don’t really give a fuck, haha.” The high pitch, nervous laughter seemed to disarm the atmosphere a bit and I saw her smile slightly back at me.

“Jesus, were we that loud?” she managed, awkwardly face-palming and letting out a grown of embarrassment.

I stood still, a few steps away from my sister. Thoughts ran wild in my mind. *Should I push it?*

“I mean, not that loud, hah. I remember thinking Thomas was probably a virgin.” I decided to be brave and go for it. Well, that was what I told myself. In reality the pent up horniness from the past couple months took over and I said things I wouldn’t have in normal circumstances.

“Oh my god. Can we not talk about this? Seriously, I am dying here,” she responded, completely avoiding my gaze and red all over. I swallowed. Without a doubt, this was a dangerous game I was playing.

“Phh,” I snorted. “It’s okay Katie, we can’t all have massive dicks you know. Thomas does what he can! He’s trying his best!” I put on my best joking voice and to make my inappropriate comments as casual as possible.

Thankfully, she laughed. I couldn’t believe it had worked. “Stop!” she yelled. “Thomas dick is perfectly fine thank you very much!”

“Yea, if you like being fucked by a baby carrot.”

She laughed again, this time loudly and bereft of any sign of lingering shyness. “You’re AWFUL!” She squealed.” I saw you in swimming trunks you know, you ain’t packing yourself to be talking shit.”

I couldn’t believe my ears. Did my sister really just say that? Judging from her smirk, she was very proud of herself for coming up with such quippy remark.

“I’ll have you know!” I started, gesticulating wildly. “My dick is pretty huge and most DEFINITELY more impressive than freaking Thomas’s!”

She looked at me with an amused expression and arms crossed. “Suuure, bud.”

I looked at her absolutely stupefied. *That bitch*.

I quickly held my grey sweatpants and started to pull them down. “Have a fucking look!”

“Stop!” She shrieked as she ran out of my room, fending her eyes in pretend disgust. Before she left though, I noticed a wide grin on her face.

She didn’t mind this. We had just bickered jokingly about her having sex and my dick size. I couldn’t believe it. I stood there with my boxers half visible and plain shock pained on my face. That was the weirdest, most inappropriate interaction I had had with Katie ever.

“I will be quiet, I am sorry!” I heard her yell from downstairs.

I walked to the door to shut it and yelled ‘you better!’ in response. I barely heard it but there it was indeed, Katie countering with: “Or what? You gonna whip out your cock?”

Unbothered, I took the rest of the evening to study in peace and quiet. It was nice and I learned a lot during that time. However, I also decided I’d make it my mission to show Katie my dick. I had no idea how or when but my sister would see my penis and be impressed with it. I had to make sure of it.

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^(Thank you so much for reading part 3 of my story! You guys are awesome! Sorry for kinda lacklustre chapter but you know, set up is needed! As always, if you need anything or simply wanna chat send me a pm! See ya in part 4!)

Source: reddit.com/r/gonewildstories/comments/ha6va0/mf_how_my_stepsister_18f_learned_that_i_heard_her