I've decided to write a series of stories of how my SIL moving in with us changed my marriage for the better and improved our lives. And no I did not fuck my SIL!

First and foremost, my wife and I have been married for 5 years now. These events happened when we were around three years into our marriage, in our late 20s. Her younger sister was coming back from college and asked if she could move in with us since she didn't want to deal with her parents' constant nagging of her lifestyle as an out-of-college early 20s woman who still wanted to party without restrictions but also didn't feel like being a responsible adult just yet. My wife asked me if I would be ok with that and I said sure why not.

I have to admit that I'd been sneaking at sniffing her little sister's panties whenever she came over during holiday breaks for a few years now. So the thought of having her in our house was too arousing todeny myself that treat. We live in a normal house, three bedrooms and two bathrooms. We have our master, a room I use as my office, and the guestroom that became my SIL's room.

My wife is a very attractive women and so is my SIL. Heck even my MIL is still looking good in her late 50s. I love my wife and think she is absolutely stunning. However, there is something so attractive about my SIL that I can't really explain. Her scent, not her perfume or lotion or body wash, her actual scent as a women calls to me. I'm sure it's the same reason I am so obsessed with my wife. But my SIL's natural flirty-ness and slutty lifestyle takes her to another level. My wife in contrast is much more reserved and conservative in every aspect of life. I am the one and only man she's been with. Her sister? Well she's got quite the milage on her.

Moving day comes and we all help bring boxes into the house. As my SIL starts unpacking my wife suggests they go shopping for decorations for the room. SIL agrees and tells her to give her a minute to change and off they go. I bolted to her room as soon as they pulled off the driveway. I start going through her boxes looking for panties and realize she had already put them away in the dresser. Unsurprisingly it's all VS and PINK panties and bras unlike my wife who wears plain cotton Hanes or the like. Going through her panty drawer got my heart going and I couldn't resist looking in the hamper. Sure enough I found her leggings and panties peeled and rolled down stuck in the leggings. I stupidly took them off and started sniffing them. OMG they were incredible! Freshly worn panties. Her aroma was intoxicating. I rubbed her gusset into my nostrils to keep her scent deep in my nose. I pulled my pants down and started stroking with her panties. As I continued panic set in. She would definitely notice that her panties where not in her leggings anymore so I decided to put them on along with the leggings and roll them down like must have done. As I did that I looked in the mirror and damn I have a nice butt lol.

With her leggings and panties on I kept rubbing my dick through the fabric and just enjoyed the moment. I didn't want to cum though since my wife and I are regular in the sack and I didn't want to raise any suspicion. So I rolled down the legging and panties and though I did a good job at replicating how I found them and put them back in the hamper. I left the room and went about my business with the scent of her pussy still deep in my nostrils.

When they came back from the store they had lots of stuff to hang up. My wife asked me to please help put it up for her sister and she'd greatly appreciate it. Then my SIL also said she's be soooo grateful if I put things up for her and gave me wink. I got my tools from the garage and started putting thigs up. My SIL came into the room soon after to continue to put away her things. Out of no where she said "ugh I need to change into something more comfortable hope you don't mind" and with that she pulls down her jeans and exposes her pink thong. I couldn't take my eyes of her. Man she has a fat pussy. It looked amazing. She goes to the dresser and takes out a pair of baby blue biker shorts and puts them on. She was stretching them to their limit. I could still see her pink thong through the fabric. Then she comes over and asks if I could show her how to use the drill. I said sure but you can't reach. So she asked me if I had a step stool. I do, so I went and got it. She stepped up and was messing around with the drill as I starred into her ass eating up her shorts. It took all my will to restrain myself from grabbing her hips and burying my face in her ass. I stroke up a conversation about how college went and how she liked it. She began to tell me about her classes and friends and parties. I admitted that her sister had told me stories about what she was doing out there in college far away from home. She turned around "OMG that snitch! So what did she tell you about my college life?" I told her about how I knew her circle of girlfriends had a bet on who could fuck the most guys in a semester. I asked her if she won and she said no way that one of her friends was a total slut and that she came in second place. Then she stepped down from the step stool and got her phone to show me her friends and point out the slut who won the challenge. She was showing me picture of a spring break and she was wearing a string thong bikini. She noticed me starring at her in the picture and asked "Cute right? Yeah that bikini is so hot I'm glad I still have it" I was sitting there on the bed with a hard on and had to change the subject.

Me: So your sister tells me you had a boyfriend freshmen year and you had quite the breakup. Are you completely over it by now?

SIL: Yeah, that was quite something. I think it ruined me in a way though. But that's what I get for choosing a black guy as my first.

Me: Whoa! What does him being black have to do with anything?

...she looks at me and points both hands to her crotch...

SIL: Well, you know. He was huge! I feel like that made fucking other guys after him boring.

Me: There are plenty of non-black huge guys in the world.

SIL: Yeah, but it's not the same. No one's ever fucked me like him. None of the other 16 guys I fucked in a row fucked as good.

Me: 16 in a row?!?!?

SIL: Shut up! You're making it sound like I'm a total slut. How embracing! I wish I was more like my sister.

Me: What do you mean?

SIL: Well she's only been with you and you're such an amazing guy! I wish I could find someone like you one day. Hey do you have any single brothers?

Me: Nope, one and only.

SIL: Too bad. You're quite the catch BIL!

...then she turns to look at me dead in the eyes...

SIL: So tell me, what do you think about my thong and shorts? I saw you looking!

Me: Sorry, you just took me by surprise taking off your pants in front of me like that.

SIL: It's ok, we're family after all. Don't worry about it. But really what do you think?

Me: Honestly, I wish your sister would wear something like that from time to time.

SIL: Yeah, she's kind of prude haha. But don't worry, I can help you with that!

Me: How so?

SIL: Well, we love to go shopping together. And I only brought a few things with me. Dumped a lot of my clothes before coming back so I definitely need to go shopping. I'll take her along with me!

With that she left the room. I managed to finish up putting up her things and left the room too. My wife was really happy that I was being so nice about her sister moving in and she told me her little sis asked her to go shopping with her and asked if I was ok with that. I said "babe you guys can go out any time you want no need to ask if I'm ok with it." She smiled and told her sis if they should head out. My SIL looked at me and said "sure, just give me a minute I don't want to go out half naked!" and my wife let out a chuckle "like you would mind girl! that's your usual outfit" Her sister without missing a beat responded as she was walking back to her room "I guess being in your house I'm already turning into a prude like you sis!" My wife turned to me in disbelief "can you believe her calling me a prude?" and I tried to deny it but my face betrayed me and she insisted "OMG you do think I'm a prude too don't you?" I had to confess "maybe just a little babe but that's not a bad thing." My SIL came back wearing a new outfit and off they went.

I was too curious thinking back to burying my face in my SIL's ass earlier so I went to her room and pulled out her thong and shorts from the hamper. I was so turned on to find that the thong having only been worn for a few hours was so wet! I had to have a taste and licked it. It was sooooo delicious and I proceeded to stroke my hard dick with the thong thinking back to having her ass on my face earlier. Then, after a while I began to tease the head of my dick with the thong and rubbed her wetness on my head. Again, I had to resist cumming and put things back in the hamper. Went about my business doing chores and they eventually came back from the store a few hours later as I was watching tv. The first thing I noticed was the VS bags coming through the door. Then other bags from other stores but my curiosity was stuck on the VS bags. When my SIL saw me starring at the bags she came over and nudged me with her elbow and winked "told ya' I'd help you out!" and to my surprise my wife grabbed three about of the four bags and took them to our room. My SIL looked back at me excited giving me the thumbs up.

When they came back from their rooms after putting away the clothes my wife talked about making dinner and my SIL offered to help but my wife said she would handle it. I noticed my SIL had changed into a hoodie and sweatpants. She switched between sitting in the kitchen with my wife and coming over to watch TV. On one of the trips back to the couch my SIL turned to the kitchen to double check that my wife was washing something in the sink and looked at me "hey check it out!" and she lifted her hoodie a little and pulled up a rhinestone strap showing me her thong "we got matching ones!" and she giggled but covered her mouth with her other hand. I was really surprised and yelled/whispered "she bought thongs!?" and my SIL looked at me like an idiot "not dummy it's not a thong" and she got up and walked towards the kitchen, my wife still washing up in the sink. Then my SIL pulls her sweatpants down and reveals a satin burgundy Brazilian panty with her ass eating up most of it and she turns to me with a diabolical smile and pulls up her sweatpants and sits by the kitchen island. I immediately jumped from the couch and speed-walked to the kitchen to join in the conversation.

My SIL asked if there were any rules she needed to follow to be a good guest and I jumped in "you're already being great!" Then my wife commented "Yeah right, it's only a matter of time before this one gets in trouble" pointing at her sister. The my mind began to drift back to the image of my SIL's ass eating up her Brazilian panties and her pink thong from earlier and her panties before that from this morning and I remembered how I'd smeared her wetness onto my dick. Then my wife snapped me back to reality "Hey! Sis is asking about rules babe." I said "As long as you don't come home stumbling drunk with strangers I think we'll be ok" and my wife jumps in to my surprise to defend her sister "whoa wait a minute! So you'd rather have her go stumbling drunk to some different random stranger's house every weekend? What if she is raped or killed?" and her sister jumps in too "wait wait wait what do you mean every weekend? Is that what you think of me that I'm some slut getting drunk and fucking random guys left and right every weekend?" My wife immediately responded "well wouldn't I know what you like to do on the weekends miss 'college experience'." and her sister doubled down "you're just jealous about not going to college and having 'the experience' sis." My wife looked at me and didn't deny it at all she just concluded "shut up sis let's just have dinner." I was curious about my wife's reaction and it stuck with me until we went to bed.

At bed time my wife went to shower and I was just on my phone. Eventually she came out of the bathroom and got something from the dresser and ran back to the backroom. She came out again after a couple of minutes and blushed as soon as I laid my eyes on her. She was wearing a cup-less teddy which also had an open crotch. I immediately bricked my boxers and fucked her with my eyes. She removed her arms that were covering her breasts and put her hands on her waist and cat walked towards me "so... what do you think? do you like it babe?" I could hardly answer "wow babe you look amazing! come here!" and she hopped on the bed and reached for my crotch. She immediately noticed my erection and went on "mmm yeah you definitely like my slutty outfit don't you?" I proceeded to ask "so is this what you got on your shopping spree?" she floored me by saying "nope, sis actually gave it to me." I was so stunned I didn't know what to say. She continued "but don't worry she promised she only wore it a few times so it's not like it's all slutted out or anything. Plus I already washed earlier." Knowing that this was my SIL's lingerie got my blood flowing even harder. I threw my wife on her back and began to kiss her from her neck down to her pussy and went to town on her clit. She actually had to tell me to take is easy that I was being too rough. So I toned it down and gave her long slow strokes with my tongue over and over and over on her clit until she climaxed.

After she came back from her orgasm she jumped up "ok now it's my turn and ripped my boxers off with a swift pull. She started to kiss my balls and then my hard dick "somebody didn't shower today..." I immediately remembered about rubbing my SIL's wet panties on my dick and began to panic but before I could react my wife engulfed half my dick in her mouth. She sucked and licked and knowing she was tasting her sister made me moan like a mad man. She continued "mmm it's actually not bad. And you sure seem to be enjoying yourself! I think this slutty outfit is making me suck dick like a slut haha I don't even mind that you didn't shower babe." I was lost in the lust of knowing my wife was wearing my SIL's lingerie while sucking me off with the her taste on me. She went on "babe your so fucking hard! Omg I love it! You must really like me being a slut. Does me being a slut turn you on babe?" I just nodded in agreement. She continued "fuck babe it's so fucking hard. I want it inside me, now!" and she jumped onto my hard dick and began to ride me moving her hips in all directions "fuck, you're so... fucking.. hard..." she put her hands on my chest for leverage and began to grind me hard. I knew that was my cue to grab her tits and suck them both at the same time. That always takes her over the edge. And surely enough it did this time too. She moaned "fuck babe... fuck.. you're so... fucking... hard...fuuuuuuuck!" and I could feel her juices dripping down to my balls as she came all over me. Then she collapsed onto my chest breathing heavily "babe.. fuck... you're so fucking hard.. why are you so hard today?" I grabbed her ass and with my hard dick still inside her whispered in her ear "I like you being such a slut babe. Watching you go crazy for cock is so sexy. I love it!" I began to move her hips "you're being such a good little slut tonight babe" she let out a soft moan and replied "omg babe stop." and I pressed on "stop what? I know you like being my dirty little slut. Don't you? Tell me!" and she complied "yes daddy" (btw when she's in the zone all hot and horny she calls me daddy and instead of dick she likes to say cock) and I pressed more "tell me! tell me you like being my little fucking slut!" and she sat up again and started to grind me "yes daddy! I love your hard cock daddy! I love being your dirty little slut! fuck me with your hard cock daddy! fuck your dirty little sluuuuuuuu..." and we both came hard. We were immobile for a minute or so and then she pulled away oozing and dripping my cum all over and exclaimed "OMG babe! what the hell you came so much! Is this what me being slutty does to you? gets you so rock hard and cumming by the gallon?" We both laughed and she ran off to the bathroom to clean herself up. When she came back she put on her pjs and I put on clean boxers. We spooned all night and had a great night sleep.