Little Sis' Twily
Ugh, your head hurts. All you remember was going to bed and closing your eyes, but now you feel dirt beneath you, along with something soft? Were you wearing fuzzy clothes when you went to bed? Actually, are you wearing clothes at all now?
You reach out, assuming you're using your arm, but as you open your eyes see it's a long white thing. Wait, what? You stare at it, and it's a hoof. Not that of a normal horse, though, your leg is thick and the hoof doesn't protrude out from it at all. You stand up on all fours, guessing it won't work to try on two, and observe your surroundings. Cream coloured buildings with fuchsia trims are everywhere, not the type of thing you'd see in your old world. Well, it's not really a problem, since now it's occurred to you where you are.
Ponyville, the place you always dreamed of living, but thought impossible. But where is everypony? Well, the shimmering crystal castle over there should have the answers, at least in book form. You make your way over to it and before opening the door look at your reflection on the walls. You're a white earth pony mare with a white mane and grey eyes. Your cutie mark is a grey question mark with a bit of a spiral shape. So you're like an anonymous pony but even more plain? Well, that's good enough.
You open the unlocked doors with your hoof and peer inside cautiously. The décor is even better in person than in the show, and you eagerly trot in, wanting to meet everyone's favourite purple pony princess. Curiously, no one came to greet you at the door, so you decide to head into the library where you're sure you'll find who you're looking for.
The corridors are very confusing and it takes you a lot of wrong turns to make it, but finally you open a door and are greeted with the sight of hundreds of books, along with something far better. A purple pony is sitting in a chair, reading in silence with a calm smile on her face. She looks... smaller than you remember, but still adorable and nerdy. You decide to approach her, and hearing your hoofsteps, she looks over to you with wide eyes, before springing out of the chair and rushing towards you with a "Big sister!"
Wait, big sister? Twilight doesn't have one of those, and now that you see her closer, she's clearly a little filly. She nuzzles your chest fur happily and looks up at you with her big dark eyes sparkling, "Big sister I'm so glad you're here! I missed you heaps and heaps!"
Okay, this is very strange, but it's not exactly something you would pass up. You don't know what happened to everypony else, but you'll gladly take this opportunity to have fun with Twi. Not even hesitating, you run a hoof along her flanks. She has her cutie mark already, but probably only recently. She's so soft and her purple fur is thin and silky. Twilight looks at you in surprise but doesn't protest the touching. You feel all over her tiny body, and she feels marshmallow-y to the touch.
"Big sister..." Twi murmurs as you touch a hoof to her slit. Her folds are pink and squishy and you run your hoof up and down several times before focusing on her clit. She's not wet yet though, and she lets out a squeak of discomfort. Well, no problem, because you are certainly wet given the situation. You touch your hoof to your own pussy and rub it in a circular motion for a few moments. It feels good and you don't really want to stop, but it will feel even better after you do Twilight first. Now that your hoof is wet, you start to rub Twilight again, and now she seems to be enjoying it more. You slowly push her down onto her back, laying atop the carpet on the floor, and rub her harder as she begins to produce her own moisture.
You sit down and dip the tip of your hoof into Twilight occasionally to keep it interesting, while getting yourself off with your other hoof. You can't really fit the hoof inside of yourself due to the size and shape, but it still feels amazing. You notice Twilight's little horn glowing and get worried for a second, but then you see a magical aura form around your hips. A long magical object, rounded at the tip, is now coming from where your pussy is. It doesn't manifest as anything properly, but stays as a partially transparent shape, sparkling also. This is perfect, and you make quick use of it as you begin to rub it against Twilight's cunt.
"Big sister you need to- go in!" Twilight squeaks shyly, her face red with blush. You do just that and begin to push inside slowly, heaving a little with effort as she's very tight. You can't feel her insides but can see them opening around the magical object. Finally you pop in enough to start thrusting in and out very slowly, still rubbing at Twilight's clit rapidly with a hoof. As her pussy begins to stretch open she lets out a soft moan of pleasure, only to cover her mouth in embarrassment. You would tell her there's no need to do that, but it's adorable when she acts like this.
Deeper and deeper you push until your own cunt is pressed against the filly's. Your pussy lips are squished together and you can feel the intense heat of Twilight's arousal. You begin to thrust in and out harder, your pussies making a quiet wet slap sound each time they collide, and you feel yourself beginning to shudder. Twilight's little belly is protruding a little each time the object goes in, and you love watching it stretch her insides. You begin to rub at her waist as you continue pounding her, and even give her a gentle kiss which causes her to blush even more.
"Big sister I think I'm going to... to..." Twilight pauses nervously, her lips quivering, but forces the words out "I might be going to cum, big sister!" and as she says that, she lets out a high pitched moan, arching her back as her eyelids flutter and her cunt clenches so tightly that you can't pull out. Instead, you begin to wiggle up and down, grinding against her trembling hot pussy, your clits twitching happily until finally you feel your own insides clenching and you orgasm hard, rubbing yourself briskly with a hoof to prolong it.
It's not quite enough though. You begin to get into a steady rhythm once more as Twilight's pussy loosens a little to allow you more movement, and you pull her upwards into a sitting position. You lead her hoof towards your nethers and force her hoof inside. It's just small enough to fit while also being big enough to feel nice and tight. Twilight gets the idea and begins to pull in and out of you, her belly stretching even more in this position as you ram her hard. Her juices and yours are wetting the carpet by now, sliding down your thighs lazily. Both of you kiss and you wrap your hooves around her to hug her while you thrust your hips hard. Twilight lets out pleasured squeaks every time you slam into her, and you feel a second orgasm approaching rapidly.
"Aah!" Twilight grinds against you as you make one final thrust inside of her. Her cunt convulses around the object so hard you think she might pass out, and it causes you to climax as well. You push against her hoof harder, allowing it to press against the back of your pussy which is shaking and twitching wildly. Finally both of you slide free of the other, sweat matting your fur as cunt honey trails down your legs. Twilight looks at you happily, murmurs "Felt so good, big sister...", then closes her eyes and lays down comfortably. She's really the cutest little thing, and you rub her cheek, kissing her forehead as you step out of the room.
Now it's time to see who else you can find. Plot logic dictates they should all be foals just like Twilight, and you're excited to give all of them a great time. You decide to check the rest of the castle first, though, in case any other ponies are still in here.