Fiancés Seductive Sister

My fiancé and I have lived together for 8 years now. Things have always been good between us, especially in the bedroom, that was until she started working nights 9pm-9am 4 days on 4 days off.

We went from daily sex at least once to a few times a week as our body clocks are backwards. Even on her 1st day off Kate is too exhausted, still adjusting her body clock back to days. Needless to say I wasn't getting much this past 10 months.

Enter Teigan. Teigan was Kate's 18 year old sister, literally half our age. She moved in with us a few weeks back to be closer to her university in my home town. This was never a problem as our house is quite large; 6 bedrooms, 1 ensuite, 2 bathrooms, 2 kitchens, basically it was 2 semi-detached houses converted into 1.

Teigan never seemed to pay me much attention, which isn't surprising as she's a shallow teen and I'm average looking. I only landed Kate because I'm confident, funny, a great cook and excellent in bed (things people compensate with when not blessed with looks).

At least Teigan never used to pay me any attention, that was until days after she moved in with us. She started giving me strange looks and lingering around me for longer, I eventually guessed she either heard us having sex when Kate screams the house down or she's seen the bulge of my cock at some point, which often changes the way ladies act towards me, basically I'm 8.5 inches, uncut and fat, which helps compensate for my average looks.

Let me describe the sisters. Kate is very good looking, not like a top model but a solid 9 out of 10. Her long red hair trails to the small of her back. At 5 foot 7, 32b-26-34 and 54kg, she is very athletic and she is a real people person, always engaging and seeing the best in people.

Kate's younger sister, as commonly the case, is nothing like Kate. Teigan was average looking, black hair, chubby cheeks, 5 Foot 4, 36f-28-38, probably closer to 65-70kg, not so athletic, always on her phone and just not very likeable. She always wears baggy hoodies and unflattering pants unlike her sister who dressed to show off her fabulous curves and hints of cleavage.

As I worked from home, I would prepare everything for Kate; food for work, packing her things, house duties and such. Kate set off to work at 8pm, returned at 10am and slept until 5pm, so I always ensured I was free from 5-8 for our 3 hours of seeing each other. As I am a contractor I can keep to my own hours. As long as work fax me blueprints, I can draw up designs and send them back when I see fit.

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It was a Wednesday night around 8.30pm when I was sat on the dining room table where I like to draw designs for work. Teigan came in and sat on the attached living room sofa, never stopping the tapping on her phone. A few seconds later I look up and see her side-on in a skin-tight t-shirt, which I've never seen before.

I never noticed with all her baggy jumpers just how huge her tits were. I always told Kate "Anymore than a handful is a waste" which made her laugh and feel better, the truth was I was a huge fan of large tits.

It was at this moment that I realised I was looking at Kates little sister who is literally half my age. I shook it off and asked if I can help her with anything as she never sits in here.

She ignores me for a second still texting. I am about to speak again when she says abruptly that she came to ask me something. A second of silence I ask "What?", my eyes bouncing between her face and tits. Again she is silent.

I get annoyed and yell "Hello??" Displaying my frustration with her. She shoots me a quick glare, looking at me for the 1st time. She then quickly jumps up and stomps off past me back the way she came. My eyes were so glued to her huge tits bouncing with each step that I have no idea if she saw me staring or not.

I was beginning to think I'll just never get teenagers. I saw her later in the kitchen and asked what that was about, what she wanted to ask me. She told me she has been getting bullied in school and was trying to think of a way to tell me when I shouted at her. This made me feel bad.

Suddenly she starting talking about girls picking on her and boys calling her ugly and crying hysterically. I put a hand on her shoulder to comfort her and she collapsed into my arms, squeezing me tightly.

I held her and comforted her, telling her not to listen, that she's not ugly and they're wrong, all while trying not to think about the big tits pressing against my chest.

Eventually she looked up at me with gratitude and said she was going to bed. I told her I would do the same shortly and said goodnight.

11pm I am in bed when Teigan walks in. She asked if I could hold her again as she can't stop thinking about her bullies. I told her I'm only wearing underwear but she was walking towards the bed as I spoke. She said please as she lifted the covers like she was begging. I felt so bad, what could I do?

She climbed in wearing baggy pyjamas and snuggled up to me, her chest against mine and a leg over my body, her knee very close to my crotch. My 1st thought, as I put my arms around her, is that she isn't wearing a bra. Her pyjamas were a thin layer of cotton which meant I could feel her large weighty chest crushing mine.

Within seconds I was hard as a rock. Unfortunately my now 10.5 inches grew in the direction of her knee, and made contact. She rubbed her knee down the length of it and I had to shift myself, telling her to be careful to which she replied "I don't know what you mean". Nothing else happened and minutes later I had her go back to her own bed.

That night my mind was racing with questions and lust. Was any of her story real? If it was, is she using it as an excuse? Or is this just all in my perverted head?

The next day Teigan came down again after 8pm, after Kate sets off to work. This time she was wearing a 2-piece bikini. Thin triangles that would cover more than half of Kates breats barely concealed Teigans and my eyes were fixed. I imagine I even had my mouth open.

"Are these no good?" She asks. "I was hoping to jump in your hot tub if that's okay?" I finally snap out of it and stammer "Err, yeah, urmm, it - it needs, urmm, filling up 1st", trying to maintain eye contact.

"That's fine", she says as she bounces down on the sofa dragging my eyes to her bouncing tits practically exposed to me. "Would you mind filling it up for me? I don't know how to do it." I quickly obliged and once done, told her I was having an early night and headed up. She jumped up and said good night before giving me a big long hug. I had to pull away before getting hard again.

Days went by like this with Teigan teasing me with her body, hugging me and such, me wanking furiously thinking about those huge tits.

It was a week later after Kate had her 4 days off and was back at work when I was getting things ready for the next day. I had promised to take Teigan shopping on Saturday as she doesn't drive and the nearest decent town is 4.5 miles away. I was all ready to go and got a good night sleep.

I woke up the next morning at 7am with a pleasant sensation. I was thinking about Kate grinding herself on me when I started to open my eyes and all movement stopped. I looked up and there was Teigan, sat on my crotch with a miniskirt and a baggy white tank top showing her nipples through it.

She tapped me on the face like she'd been trying to wake me up. I asked her what she's doing and she replied "You promised to take me shopping. It's time to go". My mind fixed on my erection that she's sitting on. She starts rocking back and forth saying "come on, come on, come on!" acting innocent but she must know what she's doing.

I squirm slightly and grab her hips telling her not to sit on me like this. She leans forward, causing more pleasure as she asks how come. This gives me a great view of her huge tits down her baggy tank top. I look back up to her eyes and she smiles knowingly.

I close my eyes trying to compose myself when she starts rocking back and forth again saying let's go. For a second I let her continue and enjoy the pleasure until I realise how wrong this is.

"Okay!" I say. "I'm getting up now." She bounces off me excitedly and I get up to get ready. In the car I noticed she's changed, now wearing 1 of her hoodies and jogging bottoms. We go shopping where she asks my opinion on things she's tried on. I look away explaining to her why it's not appropriate.

The rest of the day was uneventful. We return home where Kate is just getting up. We spend a few hours together and she heads off to work.

That night, once again after 8pm, Teigan comes down looking upset. I ask her what's wrong and she says nothing. Eventually I get the answer out of her. She tells me her back has been killing her for days and can't sleep because of it. I offer suggestions to her but discover what she really wants is a massage. I reluctantly agree knowing the temptation that awaits.

She tells me to let her get ready then go to her room which I do. I enter and see her faced down, naked with a tower over her backside. I asked what she was doing and she says "This is how massages are done, I've seen it on T.V." I told her that's only for a full body massage and she replies "Oh. I didn't know that. May as well do it as is though right?"

I huff and stepped forward, noticing now that she's laid with her hands under her head and her huge tits bulging out the sides. I try not to look and begin. I straddle her backside and begin working my thumbs up the sides of her lower spine, slowly and firmly, feeling her back and sides with my hands and fingers.

I gradually move my way up her back as she moans under me. I realise my fingers are moving closer to her tits, like they have a mind of their own. Soon enough I'm switching between massaging around her spine to thumbing her lats, with more and more of my hands being filled with breasts.

I manage to catch myself before I lose it completely and finish the massage like a pro. I climb down and she says thank you. I look to say you're welcome and she's turning over, giving me a 1st look of her size F tits.

I couldn't pry my eyes away. She acts confused for a moment then looks down and says "Oh, sorry. The massage felt so good I forgot", still not moving. I tell her she'd better cover up, though my eyes are still fixed. She tells me "If that's what you want" then slowly gets up to get her clothes. I finally pull myself away and leave. Once again I masterbate furiously that night.

It's Sunday, 11:30am. I have to go to the office for a meeting and like to get there an hour early to prepare. I can't find my car keys anywhere and head up to Teigans room to ask if she's seen them.

"Oh yeah. I took them last night to get my purse. I left it in your car".

"Okay", I responded, "And where are they now?"

"Don't remember. Could be anywhere really."

"Teigan this is serious. I need to go to work."

"Well, it could be the uncomfortable thing in my bra, I'm always forgetting things in there."

This whole time she never stopped texting. I told her to give me the key to which she responds "CBA". I was getting impatient. "Teigan. Give me my keys, now!" She turned her head slowly to look at me, then turned back to her phone and said if I want them to get them myself.

I had had enough. I stormed over, reached my hand down her top while she carried on texting and searched for my keys. Although I was mad, as soon as I had a handful of her huge tit in my hand I was in heaven. She turned on her side spilling more flesh into my hand and backing into my crotch as I searched. I grabbed area after area before realising there's no keys here.

I told her to tell me the truth, where my keys really are. After a bit of back and forth she says "You obviously didn't search the other side properly or you would have felt them." I removed my left hand from her right tit which I realised I was still holding it unnecessary and placed my right hand back down the left side.

Still no keys I was getting more mad but more horny at the same time, with her subtly grinding against me. I turned her on her back, straddled her, grabbed her top and ripped it open. She finally looked away from her phone, looking at me in shock. I grabbed her bra in the middle and ripped that apart too.

Now looking at her bare tits I grab them roughly and say "I see no keys here" as I squeeze her huge tits, pinching her nipples and massaging them. She moans under me, squirming and showing me how sensitive those fun bags are.

I keep massaging until she's about to cum then I stop. "My keys." I demand. She whispers pleas for me to continue and I repeat myself, "Keys!". She finally opened her top drawer next to her bed and gave them to me. I got up and left as she begged me to stay. I had to teach her a lesson. What she doesn't know is I wanked in the bathroom before leaving for work.

Everything went fine in the office and I return home around 4.30pm. I start packing Kate's lunch and as I close the fridge, I see Teigan standing there naked right in front of me.

Once again my eyes gravitate to her chest like magnets. She pauses for a second before telling me "You have a job to finish tonight." I finally manage eye contact and tell her to stop, that these games are no fair on her sister.

It was to my surprise when she showed me a video on her phone of me in her room massaging her huge tits like a man possessed. Even naked she has her phone on her. I manage to grab it and delete it when she snickers. "You really thought I would back it up?"

Now I'm worried. She steps up to me, pushes her chest into mine as she leans in and lick my ear before grabbing my hard cock through my pants and whispering "You're mine". She then gave my cock a light pat and walked away.

I was stunned frozen for a good minute or 2 before I hear Kate shouting down asking if I've seen her work badge. I shout back that it's in her handbag and carry on getting her things ready. We spend a few hours together and she sets off at 8pm as usual.

I was not mentally prepared to face Teigan, the 18 year old tease. I decided to continue my designs in an unused spare bedroom that is slowly being converted from bedroom to office. There's still a bed in it and wardrobe but also a desk and bookshelf. Being the cheapskate I am I won't move the old furniture until sold online.

Luckily I spend the whole night without seeing Teigan. I decide to head to my bed and eventually go to sleep with my mind spinning on the last few days events.

Over an hour goes by and I'm still half awake. Suddenly my door opens and I hear Teigan walking towards my bed. She whispers my name and I ignore her. She gets closer and whispers my name again. Now pulling the covers back she climbs in and snuggles up to me like before. This time though, I don't feel the thin cotton of her pyjamas, only the delicious flesh of her massive tits crushing my chest.

I was so lost at what to do. Obviously I should have kicked her out, but it felt so good and being "asleep" I could enjoy this feeling with doing nothing wrong. Soon later her hands starts moving towards my crotch. My heart starts racing as she reaches down and starts stroking me through my underwear.

Seconds later and she reaches inside grabbing my shaft and giving me an amazing hand job. She soon starts shifting below the covers and takes me into her mouth. Now I know this is going too far, my fiancé's 18 year old sister blowing me while I let her.

Honestly her technique wasn't great, not bad but nothing special. She sucked up and down with her hands not moving much, then she started sliding her way up my body. When she came to straddle me I realised this is going way too far. I was about to "wake up" when, within 1 second, she grabbed my cock, lined it up and sunk herself down on the 1st few inches.

The feeling was so good, never have I had a pussy so tight but so wet, gripping my dick like a vice as her juices lubricated it allowing it to slide in. I "wake" with a gasp of both pleasure and shock. I place my hands under her arse instinctively to stop her lowering anymore. I look her in the eye and say "Teigan! What are you doing?!"

Teigans response was to look at me seductively and start grinding her hips back and forth. This was too much and I decide to punish her by pulling her arse towards me as I thrust up with my hips, shoving another couple of inches in her at once that make her flinch with mixed pleasure and pain.

I warn her that she needs to get off me now or I will make things very bad for her, an empty threat if I'm honest. She whispers that she still has video of me mauling her tits and can send it to Kate anytime, resuming her grinding as she talks.

In the back of my mind I know that doing this would also ruin her relationship with her sister, she would have to move out of my house and her life of luxury would be over; in other words, she would never tell Kate about any of this.

My conscious mind however, controlled by my dick that was part way inside Teigan, that part of me was more dominant at this time and it said "Shit, she's got us. If we don't do as she says then we're done for"

I released my grip of Teigan allowing her to move more freely again. She instantly picks up the pace grinding back and forth on my cock trying to ease more of it inside her. Eventually she goes as deep as she can manage with half of my cock in her and begins slowly bouncing up and down on me.

I start getting into it as I take her giant tits in my hands and squeeze them as she rides me making her moan more. Soon Teigan moans "Make me scream". That's when I lost it. I flipped her on her back, my dick burying further in as I land on top of her, immediately pistoning in and out as I grab her left leg and hold it over my shoulder pulling her on her side.

I use her leg as leverage to help fuck her faster my left hand returns to her tits squeezing the flesh and pinching the nipples. Soon enough she's about to cum. I turn her on her hands and knees and grab her wrists. Holding her hands behind her back I continue thrusting in and out at full speed, her head on the carpet and her moans sounding like a woman possessed.

The result was the same as it often was with Kate. Screaming, shaking, looking like she just had a seizure and making me so hot I couldn't help but unload inside her as I came. Still in her, getting our breaths back we just lay there.

I eventually roll onto my back. Soon after, an energy deprived Teigan wrestles her way snuggle into me. She grabs my softening cock and sleepily tells me that while I was hiding all day she was putting cameras up "there, there, and there, ya see?" She continued that they're set up to stream live to her phone. That I now belong to her completely. Realising I naturally grabbed her right tit as she collapsed on me, I guess maybe she's right. We fell asleep just like that.