The next afternoon Brian, Ella, and I wait in the parking lot of Tractor Supply as my girlfriend pulls up. She gets out of the car and I make introductions "Brian, Ella, this is my girlfriend, Lexi". Lexi is about the same height as my sister, though her body type is far different. Where I would describe my sister as tight and toned, my girlfriend is curvy and voluptuous. They all greet each other and I ask "Okay, we are here now, so what are we doing at Tractor Supply?"
"First lesson, Davy". My sister smirks. "We are going to teach about ropes, so we first need to get you some ropes, and the ropes from here are way better than the cheap ones on your average BDSM website or some shady sex shop. These can actually stand up to a little struggling"
Lexi and I looked at each other. She smiled and seductively raised an eyebrow as we followed Brian and Ella inside. We quickly made our way to the area with ropes, chains, and other tie-downs and Brian, once sure no one else was around, began with his 'lesson'. "The first thing you should consider about a rope is how thick it is," he said as he picked up a colorful strand looped around a spool. "This can affect the safety as well as the feeling it gives. A thin rope can apply more pressure which will give it more of a sensation and make it leave more of a mark. The problem is that this same pressure can also cut off circulation. You have to be more careful with thin robes because they can more easily cut off blood flow and possibly cause damage" he said matter-of-factly, sounding very much like a school teacher. My sister playfully grabbed Brian's crotch and gave it a provocative rub. "Small ropes, or even things like paracord for shoelaces are very good at making precise ties or binding up sensitive bits, as long as you are careful with the pressure like he said" she added as she gave is cock a few strokes under his pants.
"Also good at creating a crotch-rope with some bite," Brian replied with a cough, trying not to be too distracted by his wife.
"I prefer a thick rope with some knots" my Ella shot back.
Clearly relaxing into, and enjoying their role as teachers, my sister and brother-in-law were eagerly explaining other aspects of selecting robes. They talked about material types, lengths and other aspects. Lexi was eagerly lapping up the information, she had always been the more studious of the two of us, while I was somewhat listening but also daydreaming about what Lexi and I might be doing with ropes later. "Hey Davy, pay attention, there is going to be a test later!" my sister said with a smirk, pulling me back to the moment. She was not entirely kidding about the test though.
Brian and Ella answered some questions from my girlfriend and I, helped us pick out some ropes, and we checked out with our newfound toys. As we were about to leave, my brother-in-law seemed to have an idea and ran back inside, soon emerging again with a newly purchased riding crop. He and my sister smiled at each other as he tested it with a good swat on her jeans-covered ass.
"Okay kiddos, part two of this lesson at home" my sister said. She looked over at my girlfriend, "Lexi, did David tell you what to bring?"
"He did," she acknowledged. "I decided on a one-piece swimsuit". I squirmed a little as she said this. Lexi looks amazing in the high-cut one piece she has. It further accentuates her already great hips.
"Perfect," my sister replied. "David, do you have either some kind of tight swimsuit or underwear?"
"Boxer Briefs."
"Okay then, see you two at home."
I had ridden to the store with Brian and Ella, no point in taking two cars, but this trip I rode home with my girlfriend. At first we did not say anything at all. I think both our minds were racing and we were some mix of nervous and excited. Finally, Lexi was the one who broke the silence "David, are we really going to do this?"
"If you are still okay with it. I think I am over how awkward I felt at first, take a look" I said, pointing at my pants, from which my cock was clearly trying to escape.
She saw my growing problem and smiled. "Okay, so I am not the only one turned on, despite the circumstances". With that she took my hand with one of hers and pulled it over to her. Trying to concentrate on her driving to guide my hand between her legs and I got the gist enough to continue on my own. She had worn a dress over leggings, one of her favorite combinations and as my hand slipped under her dress and up her leg, I could tell just how turned on she was. Her leggings were soaked at the crotch and I could not help but start to rub her through her clothes. She let out a sigh of pleasure "dammit ... wait David just wait". She cursed and pulled my hand away before returning both hands to the steering wheel.
Luckily it was not a long drive into the suburbs to my house and no sooner had she parked the car in the driveway did Lexi lean over and unzip my pants. With practiced skill she took my cock into her mouth and began swirling her tongue around my head. I moaned and reached over to once again put my hand up her dress. She accommodated by lifting one left, placing it over the steering wheel, allowing me easy access to reach into her leggings. To my surprise she was already wearing her one-piece underneath her leggings, so I pulled that aside and my index finger quickly found her clit. She moaned around my cock and began to bob her head up and down as I drew circles around her clit. She must have been especially turned on, and her clit particularly sensitive because it took almost no time before she cried out to mark her orgasm, though her lips never left my cock. After coming down off the orgasmic high, she repositioned herself and went absolutely wild on my cock. Mouth, hands, and tongue all worked in tandem and it felt like no blowjob she had ever given me before. Soon I exploded into her mouth, calling out her name as I slumped back in my seat. She swallowed my load and sat up, looking very pleased with herself. "God I needed that" she sighed. "I have been thinking about it constantly since last night".
Still breathing heavily, I slowly composed myself. "Oh my god Lex..."
"Mhmmmm, I know. More where that came from, I am still horny as hell." It seems she may have been more into this idea than even she had realized. "Let's get in there and not keep your sister and brother-in-law waiting".
We walked into the house where my sister was waiting with her signature knowing smirk. "Well, now that you two finally decided to get out of the car, we can move to part 2" she quipped. "Hand me the rope you bought, go change, and then meet in mom and dad's room."
"No need." Lexi replied. "I think we are both already wearing what we need."
"Well then follow me". We followed Ella to my parents bedroom. There Brian had already begun laying out their own rope collection on the bed. It was extensive, far more than I had seen last night. They had robes of several different colors, thicknesses, and lengths, all neatly situated and arranged on the bed. As we entered and handed over our new rope, Brian showed us how they tied their rope for storage in a way to prevent damage and tangling. Ella arranged our ropes beside their collection and then, putting her hands on her hips as if psyching herself up to the task, she asked us "Okay, you two ready?"
"As ready as I can be..." I said with a slight hesitation while Lexi simply nodded.
Ella looked at her husband and shrugged with a 'too late to turn back now' kind of expression and they both stripped down to their underwear. My sister was wearing a very tight pair of boy-short style underwear and a sports bra, Brian was wearing what looked like very expensive boxer-briefs that did very little to contain his erection. My girlfriend and I followed suit, with her stripping down to the one-piece she had worn under her clothes, and me down to my usual boxer-brief. With everyone down to their skivvies, we all took in an eyeful of each other.
"Okay beautiful people" my sister broke in "which one of you is the submissive?"
Lexi and I just looked at each other. We knew what that meant, but we had not really figured out which, if either of us, was submissive.
"Maybe you don't know, or maybe you are switches?" My sister inquired. "Which one of you fantasizes about getting tied up?" We both raise our hands. "Which one of you fantasies of tying the other one up?" Again, we both raise our hands. This actually seems to make my sister happy. "Okay, so either you are each a switch or you have not played around enough to figure out what side of the coin you fall on. That's fine, we can work with that. Brian and I switch so maybe we will just do a round of each person being the one tied up".
With that Brian picked up some rope and very clearly said "Okay then, ladies first".
Ella smiled at him and very sweetly replied "Yes, Sir."