Walking into her cloud apartment rainbow let out a sigh. It had been a long day working the weather for the upcoming season change that it required more than the usual for the year. As she walked into the main foyer of her new home and tossing her bag next to Scootaloo's, she made her way into the kitchen to get something to quench her thirst.
It had only been a month since Rainbow and Scootaloo had moved into the place and for Scootaloo to no longer be homeless. Some would argue that Rainbows old home was plenty big for two ponies to share and it was in square footing, but what it had in space it lacked in the number of rooms. Frankly Rainbow wasn’t complaining, now that she had more money coming in from being a Wonderbolt reserve she decided to splurge on amenities for the two of them. The front door opened up to the foyer which continued on into the living room. Off to the side was the kitchen, which was spacious with an island and a handmade table where they would eat meals. Both rooms had the cloud floors treated so they would simulate hardwood flooring. Off of the Living room was a hallway with five doors, two on each side, with the final door being at the end of the hall. One set of doors was for the bedrooms of Scootaloo and Rainbow respectively. The next set was a full bathroom and a spare room that had been turned into a multipurpose trophy room and the final room, that had once been the master bedroom, Rainbow had converted into a specialized room for ‘naughty fun time’. This was a room Rainbow had expressly forbidden Scootaloo from entering.

Overall It was smaller than the old home Rainbow Dash lived it, but it had more pros than cons going for it, such as having a non-cloud base structure so that any pony could rent an apartment and solving the issues of flying cloud homes and a flightless Scootaloo. The apartment belonged to PonyVille Cloud Apartments, a business venture Filthy Rich saw as PonyVille started to grow. The Average Clientele was visiting ambassadors or representatives of foreign lands, who were visiting for meetings with Princess Twilight, with a few exceptions of permanent residents. Rainbow Dash and Scootaloo were such examples.

As Rainbow walked back out of the kitchen drink in hand. She stopped as saw that she had knocked over Scootaloo's bag with her’s, but also had spilled most of its contents.

“Clunk” came the sound of her plastic glass hitting the floor. Rainbow stood almost frozen. Laying mixed in with the contents of Scootaloo's bag was as clear as day a ball gag. Not even sure how to respond to seeing this, Rainbow just sighed “I didn’t want to have this conversation so soon, but I guess I gotta.”

Not even stopping to clean up her drink, Rainbow headed towards Scootaloo’s room. “Hey Scoots you in there?” She asked knocking. After no reply came she opened up the door only to find the room. She then checked the other rooms, but no dice. Leaving Rainbows private room left unchecked. “Why am I not surprized.”

On opening the door the sound of somepony moaning. This didn’t surprise Rainbow since she had paid extra for the walls to be sound proof no questions asked. Walking further into she saw Scootaloo facing away from her using what appeared to be one of her dildos.

“Oh Rainbow, harder harder, please harder.”

“Scootaloo”

Scootaloo jumped not expecting Rainbow to be home. “Big sis… I...uh...I” she stuttered her brain almost short circuiting.
“Look Scoots, I think we should…” Rainbow stopped as a strong smell hit her nostrils. Reeling back “Woah Scoots are you in heat?”

“Yes, No, I don’t know.”

Taking a deep breath “We need to talk.” Rainbow then lead Scootaloo into the living room. After sitting on the couch She motioned for Scootaloo to sit next to her.

“Well, I guess the first thing I should talk to you about is taking other ponies things without their permission. This fell out of your bag.” Rainbow said as she pulled out the ball gag.

“Hey, my ball gag!”

“Your ball gag?”

Scootaloo remained silent.

“Okay, there's another thing we’ll need to talk about,” Rainbow said to herself. “ Say Scoots are you curious about this?” Rainbow asked implying to the ball gag and the things she kept in her back room.

“N...no it’s sick and wrong. Only ponies that are wrong in the head would do such things.” Scootaloo said her voice starting to raise.

“But Scoots I like those things. Do you think I’m sick in the head?”

Rainbow could see confusion and panic swelling up in her little sister. “Okay Scoots, breath just breath,” she said calmly.

“NO that’s what bad ponies do. Sick and bad ponies…” Scootaloo bolted from the couch. “Scootaloo wait!” But Scootaloo Slipped on the wet floor left from earlier and crashed into the wall. Causing a shelf and all its contents to come down on her. Rainbow flew next to her side. Moving stuff out of the way and making sure she wasn’t injured. Rainbow let out a sigh when she determined that Scootaloo was fine and was able to stand on her own without any help.

“Well at least you didn’t get covered in tree sap this time, am I right Scoots?”

“Yes, big sis,” Scootaloo said blankly.

“Uh… Scoots, you feeling alright?” Rainbow asked waving a hand in front of her face.

Taking a closer look Scootaloo had a far off stair along with some wet hair that was starting to become clear that it was not from Rainbows drink earlier. Looking around through the debris for the source only for eyes to widen as she saw a broken bottle.

“Oh no no no no no! I told my parents it was a stupid gift.” Rainbow said starting to hyperventilate. “Okay Rainbow just calm down. You simply need to think things through.”

Taking a seat on the couch with Scootaloo still standing motionless. “Wow. Thinking things through Rainbow, really foreign territory for you.”

“So Scootaloo has an interest in BDSM but is hesitant about it for some reason. She is currently going through heat and now she is currently under a hypnosis potion that my parents sent to me as some stupid joke. This IS THE WORST POSSIBLE THING!” Rainbow said, pulling a Rarity, but then gears started to turn in her rainbow haired head.

“Or maybe not. This might be what she needs.”

Standing up Rainbow moved over so that she was now in front of Scootaloo. “Okay Scoots can you hear what I’m saying right now.”

“Yes, big sis.”

“Alright, from here on out no matter what you are going to remember everything is that clear?” SCootaloo nodded.

“Now for some rules. First, you are going to address me as big sis, which you already do, but I will be referring to you as my little sister slut.” Rainbow said more for herself than anything. Next, she removed her clothes before continuing.
“Secondly, do you see this here?” Rainbow asked pointing to her slightly erect cock.

“Yes, big sis.”

“Good because this is your wants, needs, desires, and your everything. It is literally your whole world now understand.”

“Yes, big sis.”

“Now then undress and follow me to the back room.”

~~~~~~~~~~~~~~

Both sisters were now standing naked. Rainbow started to slowly move around Scootaloo feeling her features as she went. Taking one breast in her and liberally groping it while squeezing and tugging at the nipple, Scootaloo let out a staggered moan. “Nice, a bit large for a pegasus, but I can feel that it’s more muscle than fat as to be expected from ponies as athletic as us and somehow still bigger than mine.” Rainbow humphed at her own inadequacies. “Firm ass medium size.” Scootaloo let out a small yelp as rainbow smacked it. “And a wet and very hungry pussy,” She said as she cupped Scootaloo’s pussy and inserting a single finger, but feeling like it was going to take her whole hand.

“Okay, sister slut I want you to spread your legs and put your arms behind your back.” Scootaloo did so as Rainbow walked over to a chest and pulled out some padded restraints.

On returning, Rainbow held the items in front of her little sister slut. “Okay even though I know you’re under I’m gonna explain this anyway. This is a spreader bar it is designed to keep your hooves a good distance apart like they are now. And this is a pair of padded cuffs, they will keep your hands and arms behind your back while also reducing the risk of cutting off circulation as opposed to normal handcuffs. Since you are a first timer to this.”

Once the equipment was secured snugly, Rainbow moved so that she was now behind Scootaloo with her chest against her back. Her now erect cock was sticking out between Scootaloo’s leg and gave a twitch every now and then. Wrapping her arms around Scootaloo, Rainbow held onto one of the breasts with one hand while gently holding her cock against Scootaloo’s pussy. All while she gently rested her head on Scootaloo’s shoulder.

“Okay sister slut, I’m only going to explain this once. You are not allowed to cum.”

“Yes, big sister.”

Rainbow began to kneed Scootaloo’s breast while rubbing her cock against the opening of Scootaloo’s pussy. Making it very wet from the flowing juices coming from the opening. All along with giving sensual kisses and long licks up and down Scootaloo’s neck. Scootaloo was letting out a torrent of moans during this.

“Now sister slut, I want you to beg for my cock as sluttily as possible.”

“Oh Celestia, please give me your cock big sis. I need it pounding into my pussy, stretching my tight walls until they tear and filling my womb to the brim with your baby batter until my head explodes from the endorphins. Please please please I just need your co-o-ock.”

Rainbow gave pause, her hot breath rolling over the younger ponies neck. “Okay, I’m pretty sure a hypnosis potion does not expand one's vocabulary like that.”

“Where did you even learn some of those words?” But immediately regretted asking it and moved to cover Scootaloo’s mouth before she could answer and the moment would be lost. “Never mind, it’s not important.”

Shifting position so that she was now in front of her little sister. “Since you asked so nicely for your big sister's cock, I thought I would be generous and give it to you, but remember the the one thing you not supposed to do.”

“Yes, big sister. I’m not allowed to cum.”

“Good” Was all that Rainbow said as she pulled Scootaloo into a deep french kiss. Not wasting a moment. As both of their tongues were in a trance like dance, Rainbow started to slowly insert her cock into Scootaloo's pussy, taking care not to injure her. This lasted only briefly as Rainbow soon found that she was nutting her little sister, which was saying something since although not grossly large, the word small would definitely be the wrong word to describe Rainbow's cock. Being lost in the moment Rainbow kept pumping into Scootaloo's small but very hungry pussy, even to the point where it was hard to pull out at times. But Rainbow didn’t want things to end just yet. Pulling out as she held an edge and with Scootaloo still having yet to come, she used an old trick her parents taught her. Before unlocking their lips from each other, Rainbow inhaled deeply. Causing Scootaloo to literally have her breath be taken away.

As Scootaloo stood where she was with her knees locking just to keep her from falling down. She was motioned to sit down after Rainbow had removed the restraints so that she could rest while Rainbow put the equipment away. This also gave Rainbow a chance to think of where to go from here. Looking up to a clock there would be an hour and a half before the spell would wear off.

Then it struck her. A package that she had received last week but haven’t had the chance to use it. That combined with a few other things she had would give her the half hour to set Scootaloo up and then an hour to play.

“Alright my little sister slut, I need you to go sit in that corner on all fours while your big sister gets everything set up for round two okay.” Scootaloo did as she was told and Rainbow rush around the room not wasting any time.

Once the first part was put into place, Rainbow stepped back to admire her work. Scootaloo was now encased from nearly head to toe in a latex bitch suit. The only parts to be left exposed were her crotch and her anus along with both her breast and two holes for her eyes and one for her mouth, which was currently being held open by a ring gag. Rainbow then proceeded to place the next piece of equipment on her little sister slut. A harness, one design specifically to hold some very special toys. The first was a set of anal beads, which were covered in spike though dull enough so they wouldn’t pop a balloon and was meant for sensation than anything. However build inside of them were vibrators and a heating system, not enough to burn anyone, but to simulate the natural heat of a real cock. Although the surprise was the gyroscope motors meaning that the bead was constantly moving. The next was one of her larger dildo, similar to the anal beads by having a vibrating function and heating. Rainbow took caution with these because she wasn’t entirely sure what Scootaloo’s limits were but this was dash when both holes giving little to no resistance.

“Wow, when mom gets wind of this she is going to be so jealous.” Rainbow thought. Putting on a harness so that the two toys stayed in place. After routing the wires to the battery pack that only left the nipple clamps, also vibrating, since Rainbow noticed earlier how sensitive Scootaloo’s nipples were. Making sure everything was secured and set rainbow told Scootaloo to stay as she walked to the other side of room grabbing a chair in the process. She was going to enjoy it. Sitting down, Rainbow was now facing Scootaloo, she reached out on either side of her, grabbing two secure points meant for equipment because this was going to be a wild ride. Even when Rainbow knew she had only set the equipment to the third, out of ten, setting but even then it was intense.

Something that she kept to herself was the fact that she wore a cock ring with a proximity sensor. That's right the closer that Scootaloo got to rainbow the more intense that the toys would get, with a current max setting of three. Having prepared herself mentally Rainbow was ready.

“Alright, sister slut. Come show your big sister how much you desire her cock!”

Scootaloo took off as fast as she could, considering that she was moving on her elbows and knees, along with a sudden surge to her sensitive areas, made her drop to the ground as she made it halfway across the room. Staggering to get up she slowly made her way to Rainbow, but with conviction in her eyes. In time Scootaloo made it to her goal. With the toys going mad inside of her she slipped her open mouth around Rainbow's cock as it was leaking a small stream of precum, having it the start to slip down her eager through. Going slowly at first Scootaloo bobbed her head along the shaft, picking up the pace as she continued on.

This continued on endlessly with Rainbow shaking uncontrollably from pleasure and the buzzing from Scootaloo who just like the sound show no time of slowing. Rainbow’s cock was being devoured by her little sister slut’s greedy throat. Before she could cum, Rainbow pulled Scootaloo of her cock and moved to pick her up. As she was holding her little sister slut she removed the ring gag and the anal beads before plopping her down on the large bed that was just adjacent to them.

“Okay little sister, I’m going to make you feel like a real bitch slut and I’m going to want to hear you beg for it,” Rainbow said not even hesitating as she Climbed over Scootaloo and inserted her cock into her anus.

“Oh please big sis, do it, fill up you little sister.”

Their incoherent conversation grew to no more than babbling as both of them we lost in bliss.

“I’m going to cum Scoots!” Rainbow screamed “Do it, fill me, fill… Aaaaahhh”

Both of them collapsed on the bed as orgasms rocked their bodies.

~~~~~~~~~~~~

Rainbow looked at the clock with only a few more minutes before the potion wore off. They were in each other's embrace, having all the equipment removed and put away. Leaving them in post orgasmic bliss. Rainbow turned her head so that she made sure that the first thing Scootaloo would see was her kind gentle face.

“Big sis? I...I…” Scootaloo said as she started to panic. But Rainbow held firm in her grip, making sure she would run away. “It’s okay it’s okay. I’m not mad and there's nothing to feel ashamed about.”

“But we just did all… that.”

“And did it feel wrong.”

Scootaloo shook her head as a smile started to appear on her face. She snuggled closer to her big sister. “No, I guess it didn’t.”

“Now to have that talk from earlier, so tell your big sister Dash who told you it was so wrong anyway.”

“Well, it was after school and Diamond Tiara and Silver Spoon were making fun of me again. Then they threw my bag in the mud and that’s when the ball gag that I had bought fell out and they saw it. So they went off and told me how only bad ponies and ones who were sick in the head were into that stuff.”

Rainbow had a deadpan expression. “Why am I not surprized.”

Looking down she saw tears start to well up in Scootaloo’s eyes. Making a mental note to have a talk with Filthy Rich later about his daughter. “ Hey, now none of that you here. Now tell me what got you curious about BDSM?”

“Well when I’m on the ground, I feel so restricted Like I can’t move. One day I tie-ed my wings down and somehow I felt different. That I was free somehow. It just made me feel better. After that, I kept experimenting in private more and more where it… well, you saw the results.”

“I know Scoots and I’m fine with it really I am.”

“Really, thanks, big sis.”

“Now problem squirt,” Rainbow said giving affirmation.

“Actually big sis, can we try the Hypno again sometime.? I knew I was into bondage, but I wasn't expecting the Hypno and it was fun.”

“No problem. Now I think both of us could use a nap. We can talk about where we go from here tomorrow.” Rainbow said as she pulled the sheet over the two of them with Scootaloo giving a nod in confirmation. “Also one last thing.”

“Where in Equestria did you buy a ball gag?”