Sister Corrupts My Girlfriend

I went to college in another town with my twin sister. We are not identical, but we are damn similar, even if boy and girl. Luckily I have a decently sized cock, though my friends have joked through the years that I must have had a clit-sized cock due to actually being my sister's. And Jane (that's my sister) was mocked for not having big tits or a big butt, because she was actually me. You know how people are. We are both somewhat tall (she is too tall for a girl; I am too short for a guy), with dark long hair, slim, not big shoulders or big tits, or asses, so from a distance we look very similar. My name is Jack, by the way.

Our parents rented us a nice apartment in the college town, next to the college itself. Two floors, bedrooms on the second floor, one bathroom for both rooms (although both rooms shared a wall), living room, kitchen, another bathroom and a small side room on the first floor.

My sister quickly became quite adventurous and a week after moving there I had to get used to boys visiting her in the night and fucking her. At first she was quiet, but soon she got quite loud as she started noticing I didn't bring up her noise. Some days I would hear her yelling as she asked to be fucked harder.

I must confess I've fapped a few times listening to her, though it wasn't always. This is not the kind of story in which I end up fucking my sister. Almost.

The guys would invariably leave before I got up. I don't think I actually met many of her fuckers.

A few weeks into the second semester, she introduced me to a friend of hers, Christine. We made small talk and noticed Christine -Chris, as she preferred to be called- was quite nice, on top of being really curvaceous, unlike Jane. She also had long, blonde hair and green eyes.

One night that Chris slept over at my sister's room, as I was trying to get asleep, I heard a rap on the door, then looked at it and saw it open.

It was Christine, who entered my room wearing a long sleeping shirt.

She stood there and said "Hey Jack... can I enter?"

She didn't really wait for my answer and came and sat down next to me in my bed.

"I can't sleep and your sister is already gone as a log."

"Yeah she does that."

"Can we chat a little? I feel we never talk. I am bored too."

I sat up and we both sat on the bed so we were looking at each other. We talked a lot that night. About Tolkien, old movies, books, etc.

After a couple of hours, she said it had been nice and stood up, gave me a quick peck on the cheek, and left without saying anything else.

The next day neither of us mentioned her visit.

Jane brought a guy the next day and got fucked loudly.

A few days later, Chris came to stay over again and she repeated her midnight visit. We spoke a lot. This ritual repeated itself four more times, and the kisses on the cheek at the end each time got longer. My sister, who slept soundly through all this, was none the wiser.

The fifth night I stopped her as she left by grabbing her by the wrist: "Hey Chris, wait a minute."

Chris stopped in her tracks as I let go of her wrist.

I stood up and then took her hands again. "Hey, you and I are good friends by now, but... hey, no pressure, nothing has to change if you say no, but... uh, wanna be my girlfriend?"

It was as lame as it gets, but Chris got all red and covered her face with her hands while she nodded yes.

She stood there, shy, and I grabbed my newly minted girlfriend by the shoulders and pulled her to me. She removed her hands and we kissed in the lips. Softly, without tongue even. Then she ran away from the room. I was left there, not knowing if I had fucked up or what.

After a few minutes, she texted me on the phone. She just said "sorry I ran away, I am just very shy, but I am very happy you asked me out."

We spoke like that for a while.

The next day we told Jane we were going out.

"Damn, bro, I bring you the best girl here and you don't miss your chance to jump at Chris. Nice!"

"Hahaha, sorry sis."

"Hey and you Chris, gotta tell me, how big is my brother's cock? I've been told he has a clit sized dick since he and I were twins."

Chris once more got all red and pushed Jane away.

"We haven't done that!"

"Damn, I am sorry. I doubt you will be able to hold up too long, Chris. Poor Jack here must be really horny from listening to me get fucked. I am loud."

This was the first time the subject was brought up. I decided to not back down from Jane's attack.

"Oh she is, Chris. If you stay over in my room you will know when she brings someone over."

Chris was red, covering her face.

"It's ok Chris, I will not bring a guy until you two have fucked properly so I don't bother you."

Chris once more just nodded from behind her hands.

--

A couple of days later, Chris and I finally decided to have sex. We had french kissed properly the day before, and Jane was prodding her to fuck too, since she felt horny and wanted to bring some guy over but she had promised to wait until Chris and I had done it.

Turns out we were both virgins. Our first time was slow and tender, even if at some points I mauled her big tits with my teeth. I was on top of her until I came (in a condom), and then I was still hard, so Chris just rode me, grinding her clit against my pelvis until she came.

Chris was way too reserved and that day she tried to not yell. We made love for a few hours, but even after bringing her to an orgasm with my mouth, she made little noise, trying to keep herself from saying anything.

The next day she got up early and when I woke up she was in the kitchen preparing breakfast. Jane was next to her, interrogating her. Both were trying to keep her voices down, but they were too excited to be talking about this, so I listened to everything as I looked at them from my bedroom's door that looked over the kitchen.

"So now you gotta tell me. Jack was a virgin, right?"

"I...I don't know. Probably, yeah. I was too."

I was.

"Damn girl, what a pair of losers! But it's nice for two losers to get together!"

Jane punched Chris in the arm and laughed loudly.

"So Chris, you gotta tell me. Did my brother eat you out? or did he just fuck you once and rolled over and fell asleep?"

Chris once more covered her hands and mumbled for a while and I didn't catch that part. I assume she described all the stuff we did. Once Chris finished, Jane laughed.

"Damn, my bro. I knew he had to be horny, since I am horny as hell. You got lucky girl!"

Chris felt the interrogation had ended, so she relaxed once more and kept preparing our sandwiches.

"Chris, now tell me, how big is my brother? I need to know, for real. I need to know if I need to look for a father for my kids with a big dick or if I can choose whoever."

Chris just walked over to the kitchen's veggie holder, and grabbed a nicely sized carrot, very fat on the base, and gave it to Jane. Jane nodded approvingly saying:

-Damn girl, he is nice. I've had bigger, but he is not small at all. I can rest easy.

That seemed to end the conversation. I waited a while and then got out of my bedroom and went to have breakfast.

That night Chris went to her house (she lived with her parents) and Jane brought a guy. As always, she was very loud. The next day I woke up and the guy was gone. Jane prepared breakfast for us and as I ate my toast and drank my coffee, I noticed she had an extra carrot on her plate.

"Gotta eat my veggies, bro."

She ate the carrot whole in two bites while looking me in the eyes as she chewed.

--

Chris got a little more relaxed with the yelling the first time she stayed over and Jane brought a guy. We both sat there listening to my sister moan and ask to be fucked faster. After that, Chris yelled and moaned freely, although she never got as loud as Jane.

She also got friskier. At first we made love by holding each other closely and tenderly kissing, but after a while she got her on all four legs and asked to be fucked 'throughly'. She also asked me to pull her hair and to slap her in the ass, hard. She yelled each time I did this, and she would orgasm after a few slaps.

One day, I finished, so I pulled out and took off the condom and disposed of it. Chris suddenly started licking my cock before I could clean her up, and got me hard again. I put on another condom and fucked her again, calling her names and slapping her ass. She yelled my name.

The next day I heard them talk as I woke up, looking at them from above.

"Damn girl, finally I got to hear you yell. You are almost as loud as me."

"Yeah, though definitely not as loudly as you, Janet."

For whatever reason, Chris called Jane 'Janet'.

"Well, did you do the stuff I told you about? Get fucked in all fours, while he slaps your ass? Going raw instead of with a condom? Have him pull your hair?"

Chris was red. She continued.

"I just started taking the pill, but we are supposed to wear condoms until at least next week. But yeah, we did all the other stuff. It was great."

"I told you Chris, fucking needs to be raw, forceful. It is cute "making love" tenderly, but you will get bored of that. We women need to be taken and destroyed by a big cock. You won't notice a difference when he doesn't wear a condom, but psychologically you feel dirtier, used, it's different. You gotta try it."

"Next week, Janet, next week."

So this is where my girlfriend was getting her ideas.

As the weeks passed, Chris got more and more frisky. We stopped using condoms. She asked me to come on her face, on her mouth, on her vagina. She asked me to slap her on the face. She brought a vibrator and put it on her clit as we fucked. She also yelled loudly. She asked me to tie her up, then she tied me up and rode me. We fucked blindfolded, made me fuck her with a dildo, etc.

Most of the mornings I would hear Jane and Chris discuss what we had done the night before, or what we would do the next session. I assume everything we did was Jane's idea. Some stuff, like tying each other or the blindfolds, did nothing for Chris. However, she loved being ejaculated over. She would make me masturbate at the end of each session and come on her face, and she would use her hands to spread my semen over her skin. She once made me come in her mouth, and then kissed me with my own semen still in her mouth. Apparently that was Chris' original idea and she and Jane both seemed excited over it when they discussed it the next day. Chris rarely blushed when discussing sex with Jane anymore. She was very open and I could hear them discussing sex without having to go out of my room, unlike at the start when they used to whisper.

--

One week Chris was staying in my room, and Jane had brought one guy that was very tall and thin. I knew him from college. He was called Marcus, but I didn't even know him beyond that. Chris and I fucked that night, and after our first orgasms we stopped when we heard Janet yell. This time, though, it wasn't her typical moans, but she screamed as if she was in pain. I stopped Chris from going over to check on her.

Jane was clearly hurting though, but in a good way.

"Ouch ouch ouch yesss aaaaAAAAAAA OUCH STOP STOP THERE there. Wait. aaaaAAAAA."

She was in pain, but she seemed to enjoy it from time to time. I suspected what was happening: anal. But I didn't mention it to Chris yet. I preferred to let my sister do the talking; it was much more fun to listen in to them talking about sex.

Jane yelled like that for twenty minutes. Towards the end she was moaning like crazy, more of her usual self. Then the yelling stopped and we heard the guy leave. We also heard Jane taking a shower, which eased Chris, who seriously suspected Jane was being killed.

We didn't fuck any more that night, as Chris was distraught.

I was careful to put on an alarm early the next day. It woke me up vibrating and I stopped it. I lied on my bed, awake but pretending to be asleep. Chris woke up some time later and went to prepare herself breakfast.

I could hear her talking with Jane. They were whispering again.

"Jane, what happened last night. I was worried, but Jack didn't let me go check you up."

"You are sweet but nothing happened. Except that I... tried anal sex."

For the first time I saw my sister get red speaking of sex and cover her face.

Chris didn't understand.

"Anal sex?"

"Yeah, Marcus, the guy that came over, has a long and somewhat thin cock. I heard that was ideal for anal sex since it wouldn't hurt much the first time, but it would let me feel penetrated like nothing else. He tried going slow, but it hurt a lot."

"So did he put it in your butt? Did that hurt?"

"You bet it hurt, girl, like a motherfucker. But at the end I had a great orgasm. I was too tired to continue and I sent Marcus home after one fuck. Poor guy, I will have to have him over again. Are you gonna try it with my brother? I've heard it's better if the man has a long and thin penis, and my brother sounds more like short and fat. Dunno if I can recommend it to you two. If you try it, tell my brother to use A LOT of lube."

Chris didn't ask for anal sex that night. Or for a whole week. I thought she had forgotten the issue, until one day she said, after fucking her once, she said "I want to try anal."

I said ok. Chris went to her bag and pulled out a very big bottle of lube. She put a good amount on my hard cock. Then she put a lot more on my hand and said "Put that on my ass."

I did as told. She got herself in position and lifted her ass, which I opened with one hand and started putting lube on her anus with the other hand. This made her moan. She said:

"I feel dirty, Jack. I am a whore that needs to be fucked in the ass. Are you up for it?"

"Yeah, I am gonna fuck you in the ass like the whore you are, you whore."

Chris enjoyed being called a whore.

After I was happy with the amount of lube I had used, I put the head of my cock on the entrance of her anus.

Chris moaned at this: "I feel so dirty being fucked in the ass like this!"

I told her I had not started fucking her yet. I started pushing to get the fat head past her sphincter. She immediately started yelling and cursing at me. I asked her if she wanted me to stop. She said no.

I started pushing again. Chris yelled some more, but I ignored her. I eventually got my cock's head inside. Her ass was tight and felt super hot. I stood there until Chris stopped yelling. Then I started pushing my cock inside, which prompted way more yelling from Chris.

"OOOOH MOTHERFUCKER I THOUGHT YOU WERE ALL THE WAY IN AAAH!"

I ignored her and slowly pushed myself inside, until my balls touched her. I stopped there for a minute. I could hear her breathing hard. I embraced her from behind and kissed her in the neck.

I pulled out completely. She yelled when my cock got out of her ass. Her asshole was left gaping, and I used this opportunity to grab the lube bottle and put it directly against her anus and push it to fill it with lube.

I put my cock back on the entrance and pushed again. This time it entered easily. She yelled even more.

"AAAAAH IT HURTS. THIS IS YOUR FAULT YOU IDIOT JANE, OOOUCH AAAAH."

She assumed that Jane was listening and cursed her and also me as we fucked. I pumped her back and forth slowly, and only picked up the pace as she asked. Soon I was pistoning her at almost the same speed as our regular fucking.

"Slap me in the ass, Jack, slap me like a whore. OOOOOH I AM A WHORE I LIKE IT IN THE ASS OOOH."

I slapped her in the ass and she yelled too. She kept calling herself a whore, and I followed suit. She had a strong orgasm just from anal soon, but asked me to keep fucking her in the ass. I did. I also reached around to her vagina and fingered her clit. This made her come again. At that point she asked me to get out.

We didn't fuck again. I had not come, and she just gave me a handjob, made me come on her tits, then she forced me lick to my semen off her tits, and then turned over and went to sleep. I slept too.

The next day I heard them talk.

"Oh Janet, anal sex is great. That was the best orgasm I've ever had. Dunno if I can do it every night but it is going to be a regular."

Jane nodded.

"Oh yeah, I definitely haven't had it every night but it is pretty good."

--

It's weird going to college when your sister fucks a different guy almost every day. Particularly if you look a lot like your sister in certain lights or clothes.

You get knowing nods, or people talking and pointing at you and snickering. At two points some guys grabbed my ass, and then apologized when they saw I was not Jane. I should grow a beard, but... I can't, actually.

One rule we got early on, was that Jane didn't fuck my friends. This meant I had very few friends, because Jane would fuck them before I met them. Some of them were ugly and not very fuckable. But I had a good friend that had followed me from high school, Mark.

Mark was taller than me, and more athletic. If he liked Jane, he didn't show it. We both played basketball in high school, but soon dropped out of it in college. We both kept in shape. We had showered together and I had noticed he had a very long and thick cock. Not that I was interested, but sooner or later, showering together you get to see the damn thing. And even without the benefit of showering, you could easily see he had a big long cock in his pants if you knew what you were looking for. The thing would flop around as he ran and jumped.

Mark would come over to the apartment from time to time, to play games or study. He actually ignored Jane, and Jane ignored him, so I assumed they didn't fuck. They had known each other since high school, so maybe they had fucked there, dunno. Mark had had a couple of girlfriends, though he was single and apparently not looking for one right now. His exes were all more voluptuous than Jane anyway, so maybe she wasn't his type.

But once I started dating Chris, he would openly flirt with her. In a joking way, but still. Given the way Chris and I fucked, I was not worried about Mark. I endured it and said nothing. It was never persistent, just a joke going over the line one week, or a reference to his big cock the next.

My relationship with Mark would drastically change thanks to Chris and my sister.

--

One day we were in bed after a session of anal, Chris resting before fucking again, both listening to Jane get fucked. At one point she stopped fucking, opened her door, and went downstairs. She opened the door of the apartment, closed it and went back to her room. But the footsteps were louder on the way up.

I told Chris: "I guess her fuckboy left"

Chris nodded. Then, almost immediately, the moaning started again. Jane was moaning louder than usual and started talking:

"You, are you hard already? mmmMMMM oooooh yes like that. Come over here. Give me that. Mmmmmm. MMMMMM."

We didn't hear her speak again, but she moaned loudly. more like she had something in her mouth.

I started doing sex math in my head and said.

"Chris, I think she has two guys and is sucking one as she fucks the other."

At this point, Chris opened her eyes like saucers. She pushed me on the bed and started riding me. But she put a finger on her mouth and said "quiet". She grinded on me as we listened to my sister get fucked. We heard Jane have a loud orgasm, but her yells were muffled by something. After a while we heard a guy yell and moan. He said "I am coming". And then another, different male voice said "Ugh I am coming too uuuugh."

That confirmed it.

Chris started grinding slower, closing her eyes as she enjoyed my cock inside her, and pressed her clit on my pelvis. I grabbed her tits with my hands and pressed her nipples with my fingers. She muffled a moan.

Chris opened her eyes, without stopping moving over my cock, grabbing her bag. She pulled out a dildo she had made me fuck her with a couple of times, but now started to suck it as she fucked me. She had her eyes closed, writhing with the cock in her mouth. Chris kept doing this at a slow pace.