Inspiration: 
>>She hops over to Dash and Rainbow then
>to Dash and Rainbow
hmm

Prompt I made:
>Bow and Windy had identical twins
>One is named Rainbow, and the other is named Dash
>Thanks to near identical personalities, abilities, and cutie marks (the color scheme is flipped, but the shape is the same), they can switch places almost flawlessly
>Since ponies have heard them be referred to as "Rainbow" and "Dash" and are under the impression that they are dealing with one pony and not two, they come to the conclusion that they are simply dealing with one pony named "Rainbow Dash"
>It fits with pony naming conventions, so they're happy, and both twins are fine with being referred to as such
>Any discrepancy in Rainbow Dash's personality is due to misinformation or misunderstanding between the two of them when they switch places
>Moments where she seems to have to re-learn the same life lesson more than once is because only Rainbow or Dash underwent the lesson, and it only had a lasting impression on one of them
>This also leads to her seemingly tsundere personality
>One twin tends to lean towards mushiness, and the other one leans further away from it
>So when she seems to show tenderness one day but brashness the next, this confuses ponies; it is simply the case of Rainbow showing up one day, and Dash showing up the next
>This makes dating Anon very confusing
>At first, Rainbow and Dash didn't take the relationship very seriously and swapped places with each other whenever they felt like it
>They never bothered to tell Anon that they are two different ponies, because they thought this was just a fling
>But Rainbow, who leans towards mushiness, is quickly falling in love with Anon, and she knows that Dash doesn't feel the same way she does
>She wants an exclusive relationship with Anon, and now she has to think of a way to tell Anon that she's been fooling him and letting him have sex with her twin sister

-----
Story continuation:

>You are Anon, and you are in a very good mood.
>You are laying on a hillside underneath a big oak tree, and you are curled up against Rainbow Dash.
>It was weird at first, resting your head against her chest instead of the other way around, but you can't deny that the way she hugs you and wraps her wings around your make makes you feel safe.
>The rustling of the tree leaves and the cool, gentle gusts of wind playing with the loose fringes of your shirt is hypnotic.
>And with your ear pressed against her furry chest, the dull thuds of Rainbow Dash's heartbeat is nearly enough to lull you to sleep.
>Sleepy and comfortable, you tighten your grip on your marefriend and wriggle a little bit deeper into her warm chest tuft.
>"Mmmm..."
>You feel her press a kiss on the top of your messy mop of hair, and you can't help the little smile that tugs on your lips.
>This must be what peace feels like.
>You can feel yourself drifting off to sleep.
>Little half-images of infant dreams play across your darkened vision, and your limbs feel somehow disconnected from you.
>Just a few more seconds, and you'll be having the most restful nap in a long time.
>You distantly hear something gliding through the wind, and it takes a moment for you to acknowledge that it's probably just another pegasus, flying around and doing her business.
>There'a a loud rustle of leaves and branches from just above you, but you pay it no mind.
>You have naps to take and dreams to enjoy, now.
>>"Pssst!"
>Your awareness sharpens unpleasantly at the equally sharp hiss coming from above you, and you resist the urge to stir.
>>"Hey, sis!"
>Huh.
>Weird, that sounds like Rainbow Dash.
>But your marefriend is currently holding you; she's not 10 or 15 feet above your head.
>How odd.
>>"Is he asleep?"
>Your marefriend's grip tightens briefly, and you let out a pleased sigh.
>Still, you don't move.
>This confusion can be figured out later, when you wake up.
>"Yeah," comes a whispered voices from just inches above your head, "He is."
>You WOULD be, if Rainbow and this familiar-sounding stranger would just stop talking for 10 more seconds.
>There's a flap, and then something lands on the ground next to you.
>>"Cool.  Look, we switched last week; it's my turn with him for tonight's movie, right?"
>"Nuh-uh, Dashie.  We agreed that you owed me for taking over your shift at the weather factory when Anon got sick last month.  It's my turn with him this week."
>Your marefriend's grip tightens on you, possessively.
>>"C'mon, Rainbow!  Spitfire's been riding my flanks today, and I NEED to get off."
>"Well, too bad!  Me and Anon have something planned tonight.  Just come over tomorrow night, Dashie."
>>"Ugh, FINE.  Did anything important happen today?"
>"Anon bought us that latest Daring Doo book today, so don't forget.  The last time you did, Anon suspected something."
>>"I know, I know.  So, uh... c-can I read it?"
>"Go ahead, it's on the kitchen ta-"
"Hnnng..."
>You wish that your marefriend and this stranger would stop whispering so loudly.
>You're so close to falling asleep and this is all so confusing to your half-asleep brain.
>You hear a choking noise to your side, and your marefriend whisper a harsh "Shhh!" from above.
>>"Shoot, I think he's waking up.  I'll talk to you later, sis!"
>"Later."
>There's a flap, a whoosh, and then... blessed silence.
>The wind continues to tug playfully at your clothes.
>The leaves keep playing their gentle orchestra as the breeze passes through them.
>Rainbow Dash's heartbeat - noticeably faster - does its job and continues to lull you to sleep.
>You've had little waking-dreams before, when you're straddling the divide between wakefulness and slumber.
>But this one takes the cake.
>Once more, you feel your marefriend kiss your on top of your head.
>The last thing you hear before you FINALLY drift off to sleep is her voice.
>"What am I going to do with you, Anon?"
---
>You are Anon, and it is a few weeks later.
>You are laying on your couch, watching a horse-film.
>Daring Doo and the Golden Feedbag.
>It's alright.
>You're mostly killing time until your marefriend comes home from work at the weather factory.
>You don't have much planned, just a night together.
>You'll watch a few movies, maybe order a pizza.
>You have a few chilled ciders in the fridge, so you're all set.
>It's 5:59 PM, and you know that Rainbow Dash never stays late at work unless she absolutely has to.
>And her commute back to your home is measured in seconds rather than minutes.
>So that means....
>CREAK
>SLAM
>"Ugghh...."
>Ahh, there she is now.
>Like clockwork.
>Rainbow Dash flutters into the living through through the open doorway looking absolutely beat.
>Her ears are flopped down against her skull with weary displeasure, and her limbs are sagging down towards the ground.
>Combined with her normally-stiff feathers looking bent and worn out, and it looks like Rainbow is fighting a losing battle against her body's desperate urge to stop flying immediately.
>Her eyes light up when she sees you, though, and her wings give a big FLAP as she puts on an extra burst of speed for you.
"Oof."
>With all the majesty and elegance of a sack of wet dish towels, Rainbow lets herself fall out of the sky and land on your chest.
>She wastes no time; she goes boneless and spreads out on top of you, trying to get as much skin-on-skin (or in her case, fur-on-skin) contact with you as possible.
>Naturally, you wrap your arms around her and hook your fingers together so that you don't slip.
>Her eyes are closed, and she almost looks like she's fallen asleep.
"Long day, babe?"
>"Ugghh..."
>Yeah, it's been a long day.
>Normally, she's freezing cold after work.
>Her job at the weather factory has her working at high altitudes, and rainclouds tend to be a little bit chilly on top of that.
>But you can feel the heat radiating off of her in waves, like she had just been working out.
>Just like when she's had a training session with the Wonderbolts; but that's not this week.
>Well, time to be a good 'colt'friend.
>You tug Rainbow Dash a little bit higher up your chest, and once she's in reach you pepper her face with kisses.
>"Hey..."
>She begins to squirm, but you can see the little smile growing on her face.
>"Stoppit."
>You kiss above her ear.
>"Stoppit, colt."
>She moves her face, and you press a smooch against the side of her muzzle.
>"I said, qui-"
>Rainbow Dash turns her head again, and you catch her smack dab on the lips with a kiss.
>Her complaints die in her throat as they're replaced by a pleased moan.
>The kiss breaks with a wet SMACK, and she cracks one of her eyes open.
>"What's the plan for tonight, Anon?"
>You let go with one of your hands and point at the TV.
"A movie, remember?"
>She shuffles her head around to peer at the screen, and her eyes light up.
>"Oh, mare!" she crows with as much energy as she's capable of, "That's Daring Doo and the Golden Feedbag!  That's such a good movie!"
>...weird.
"Yeah, I know," you say slowly, "You were the one who rented it.  You said you'd never seen it before, and you wanted to see it with me."
>Rainbow glances at you nervously, eyes now wide open and alert.
>She looks like she's been caught in a lie much bigger than fibbing about whether or not she's seen a movie before.
>So she's seen it before, but last night she acted like tonight would have been her first time watching it.
>She wanted to share the experience with you.
>"O-Oh, uh... w-well, yeah!  I... I pretended that I-"
>...wait a minute.
>You know what's happening.
>A lazy smile slowly spreads across your face, and you use your free hand to boop Rainbow Dash on the snoot.
"You silly mare, did you lie about not having seen this movie so that we could both watch it for the first time together?"
>Rainbow's panicked expression fades away, and her usual cock-sure grin takes its place.
>"You figured it out, sweetheart.  I'm always on top of the new Daring Doo stuff, but I thought that seeing it for the first time together would be special."
>She reaches out and boops you right back.
>"Think you can pretend you didn't hear that?"
>She winks at you, and you wink back at her.
"Pretend that I didn't hear what?"
>Rainbow Dash grins and settles back down on your chest, ear pressed against your chest so that she can face the TV screen.
"There's cider in the fridge, you know."
>Rainbow chuckles and slowly hauls her tired body up off your chest and hops down onto the floor.
>"I knew I kept you around for a reason, Anon."
"Are you sure it's not because of my good looks and dazzling personality?"
>She waves a wing at you in what you've been told is a playful, dismissive gesture.
>"Alright; I knew I kept you around for TWO reasons."
>You throw a pillow at her.
"Bring one back for me too!"
>" 'kay!"
>You are Anon, and you're going to have a very pleasant evening with your strange marefriend.