Substitution

by TCC56

Rating: teen
Tags: Rainbow Dash (EqG), Spitfire, My Little Pony: Friendship is Magic, Comedy, Equestria Girls
Length: 4758

Rainbow Dash promised Scootaloo a Rainboom at the next Wonderbolts show but she's been hurt. Solution: bring in another Rainbow Dash to do it for her! Two problems: Spitfire isn't fooled, and nobody taught the human Dash how to do a Rainboom.

On the last mission to save Equestria, Rainbow Dash was hurt. Not critically and she'll heal, but for now she's grounded. But she also promised that she'd do a Sonic Rainboom at the next Wonderbolts show for Scootaloo's parents, and she is not going to let her girl down.

Solution: get another Rainbow Dash.

There's just two problems.

First, Spitfire knows her team backwards and forwards and she's not fooled.

Second, the human Rainbow Dash doesn't actually know how to do a Rainboom as a pony.

I'm sure this won't cause any problems.

Written as part of the Quills & Sofas 2024 Wonderbolts Contest, in which it took second!

Featured 4/30/2024 - 5/5/2024!

Also appearing on Equestria Daily on 5/3/3024 and on 2/1/2025 as part of 30 of the Best Fanfics to Read for Rainbow Dash Day!

Published 2024-04-30 18:30:01 UTC
Last updated 2024-04-30 18:30:01 UTC

Wherein Rainbow Dash confuses and angers Spitfire for new and unusual reasons

As Captain of the Wonderbolts, Spitfire knew her team and their routines on an instinctual level. She could run through any of them in her sleep, knew every detail possible about her 'Bolts if asked, and could tell in an instant if any of them were even a fraction of a second off their mark.

She did not need that knowledge right now, because Rainbow Dash was several seconds off her mark and was visibly lagging behind the others.

The formation of four Wonderbolts turned the corner, easing into an Immelmare turn to prepare for an Icarian Sun Salutation. Rainbow Dash - the fifth Wonderbolt who was supposed to be in the formation - made the turn two point two seconds later (by Spitfire's estimation) and far enough back that the contrails of her teammates left her flight path shaky and unstable. Her approach into the Salutation was too slow and several degrees off-center. And when the others all hit the peak to break off, Dash turned the wrong direction and followed Fleetfoot rather than Misty Fly.

Spitfire turned away from the absolute travesty of her supposed rising star completely botching everything. "When Crash lands," she noted to Soarin', "Tell her to see me in my office." And it didn't take a Wonderbolt Captain to understand what that meant.

"You wanted to see me, m'am?" Rainbow Dash nosed the door open. Still in her flight suit and wings dangling at her side, she entered the office of Dread Spitfire.

Said pony patiently waited behind her desk. "Close the door behind you," she calmly suggest-ordered. And as soon as it was? "As best I can figure out, Rainbow Dash, there's only three explanations for what your damn problem is."

Rainbow Dash froze, halfway through approaching the desk. "Uh.. I've got a cold?"

Spitfire continued talking, ignoring Dash's lame excuse. "One is that you're a changeling who replaced Rainbow Dash. Which is possible, but I'm guessing it's unlikely. A proper infiltrator would know better than to try and perform tricks they couldn't and would have found an excuse to avoid practice."

There was obviously something else wrong, because Dash didn't react when she was accused of being a changeling.

"Two is that you're suffering from some kind of illness," Spitfire continued. "And I don't mean a cold or the feather flu. I mean that you've got something crippling and serious like monochromia or Manière's syndrome. But if it was something like that you'd be showing a bunch of other symptoms instead of just flying like a crippled goose."

"Hey!" That accusation, at least, got a reaction out of Rainbow Dash.

Spitfire pushed on. "Third is that you've suffered a traumatic brain injury and have forgotten everything about how to fly."

"I know how to fly!" It was a strenuous (if silly) protest, but Dash didn't sound particularly confident about it either.

"Not like you should." Spitfire leaned forward, glaring at Rainbow Dash through her sunglasses. "Now, those are what I've come up with. Do you have an alternative explanation, or should I put you in a quarantine cell until you either fess up or recover from whatever's happening to you?"

Rainbow Dash opened her mouth to speak. Then closed it. Then opened it again. And closed it. And opened it a third time.

And Spitfire interrupted her. "Explain right now or I call security."

"I'm Rainbow Dash!" The words shot out like a pie from a cannon.

Spitfire reached for her intercom.

"But not the Rainbow Dash you think I am!"

A pause. "So you're a changeling."

"No!" Rainbow hesitated. "I'm, uh…" She squirmed uncomfortably. "This would be so much easier if you knew what a human was."

Spitfire's left ear flicked. "Human. You don't look like a human."

Rainbow Dash's expression changed from frustration to relief. "You know what humans are? Wait - how? I thought the mirror was a secret!"

The sarcastic eyeroll was ruined by the sunglasses, but Spitfire wasn't going to take them off and mess up her look just for the effect. "The Wonderbolts are part of the greater Royal Guard umbrella. I'm in the loop for most security briefings, particularly when it potentially applies to one of my team. You know that, Crash."

A little smirk played across Rainbow Dash's face. "Respectfully, m'am, no I don't."

Spitfire paused. Then she grumbled. "Right. Yeah. Anyway. So where's the real Rainbow Dash?"

The human-turned-pony looked irked at the implication she wasn't Rainbow Dash - but fortunately for her she moved past it. "She got hurt on the last mission with her friends, so she asked me to come and take her place."

Now the real grumbling began. "Are you kidding me." Spitfire finally took off her sunglasses so she could rub the headache building between her eyes. "Crash, you moron. This is exactly why we have alternates and reserves. I knew when you signed up that you were probably going to get hurt and be unable to perform sometimes. If you'd told me–" She paused and corrected herself. "If she told me, it wouldn't have been a problem."

"With all due respect, m'am, she knows that." Rainbow Dash's back straightened, her posture going to attention as she realized she might get out of this if she behaved for once. "But she asked me because nobody else can do a Rainboom."

Spitfire frowned. "Nopony else can, but her doing a Rainboom isn't part of the next show's program."

"It's important that she– that I do one at the show."

The headache was already getting worse. "It isn't on the schedule. It's not even a particularly important show."

"It is to Rainbow Dash." Which made Rainbow Dash pause, face screwing up a little as she mentally reconciled talking about herself in the third person without being Trixie. "Do you know Scootaloo?"

"Cute kid. Real enthusiastic. Basically Crash's little sister." Spitfire's eyes narrowed. "And has seen the Rainboom more times than I have."

Dash nodded. "Yeah, but her parents haven't." The only response to that was an eyebrow raise, so she kept going. "They're, like, long distance explorer types who go all over Equestria to explore places and research weird creatures. They come back once a year, maybe? But they're gonna be at the next show with Scootaloo, so Rainbow Dash promised she'd do a Rainboom for them."

"Damn it Crash." Spitfire flopped backwards in her chair, eyes closed. "Alright. Fine. If she'd just said something…" The captain let out a heavy sigh and straightened back up. "To start - you're off the main routine. One of the alternates will pick up because it's pretty obvious you're nowhere near ready and I don't have the spare time to teach you all of the moves before the show. But I'll put you in there to do a Rainboom. Just the Rainboom, and just for this show. Then you're going back to human-land and I'll disembowel Rainbow Dash once she recovers."

Her response was a broad smile. "Thank you, m'am!" Then a long pause. "There's, uh, just one problem. How do I do a Rainboom?"

Several seconds of silence followed before Spitfire could find the words. "What."

Rainbow Dash's wings flicked upwards, flapping in a fit of panic. "I've only been a pony for two days! Rainbow Dash tried to teach me, but she just kept saying I needed to 'feel it' and to 'trust my instincts'!"

The desk shook as Spitfire slammed her head into it. "So now I have to teach you how to do a Rainboom in four days, despite the fact that I can't do one. Or I make some little filly sad."

Inching closer, Dash attempted to give Spitfire a comforting pat. "I'd really appreciate it if you did?"

"I am going to kill your counterpart."

Day One started with laps. Something simple because before anything else, Spitfire had to get a feel for how her new student flew.

The answer was really, really badly.

Ten laps in, Spitfire waved Rainbow Dash down. "Alright, so I'm grading on a curve since you're human and never flew before–"

"Actually, I fly all the time as a human."

Spitfire froze - not voluntarily, but her brain record-scratching forced the rest of her to pause. "Humans don't have wings."

"I do." And Rainbow Dash seemed very, very proud of that. "Of course, it's only when I pony up using my geode, but I still can totally fly!"

Spitfire just stared, having no idea what any of those words meant in this context. "...what."

This was the wrong answer, because Rainbow Dash very enthusiastically closed in to explain. "See, there's these cool magic rocks that Sunset Shimmer found in a haunted cave while we were at summer camp and we can use them to become half-human half-ponies with awesome super powers that we used to fight a camp counselor who turned into an evil plant monster so she could destroy capitalism. We could do it before the rocks but only when we played really awesome music, so we're kind of were-ponies but instead of transforming into horror movie monsters under the full moon I get superspeed when I have a guitar."

"...What."

Dash - close enough that Spitfire could taste her sweat - tilted her head to the side slightly. "I thought that was pretty straight forward."

Spitfire shook her head violently. "Okay, look, I– none of that matters, you're a pony and you said you were only here for two days. So you're a terrible flier but you're not bad for somepony who was bipedal before Monday."

It took a moment for Dash to do the mental math and confirm it was the correct day of the week - a gap in which Spitfire took the opportunity to back out of the post-workout stink cloud - before picking up. "Right, so what do I need to do so I'm good enough to Rainboom?"

"Rookie, right now you're barely good enough to stay airborne." Spitfire extended her wings to better loom - and Dash fanned hers out in response. "Your technique is a mess, your cornering's sloppy, and you're way too winded for just a few laps."

Rainbow Dash bristled at the suggestion that she was out of shape of all things.

But Spitfire kept going. "You're lucky that the Rainboom is just going in a straight line really really fast for a little while, or I'd say this was impossible. I could get you up to par, but it would take longer than we have." Her eyes critically scanned her new protege. "We'll fix your technique first, because otherwise the rest won't matter."

That seemed to placate Rainbow Dash and her wings lowered to half-raised. "Alright, so where do we start?"

Spitfire tilted her wings into a level position. "First put your wings like this." She waited a moment for Dash to copy her. "This is how you hold them while gliding. You won't be doing a ton of that, but it's the starting point for most other positions. I want you to hold that until I tell you to stop."

Dash held that position, wings rock stable. "Easy." There was a pause as she detected a trick. "How long is that gonna be for?"

For a moment, Spitfire faked thinking. Then she turned and trotted away. "Long enough for me to get a coffee. When I get back, we'll start going over the right way to flap on take-off!"

Rainbow Dash sputtered. "I'm just supposed to stand here?"

"If you can't hold a gliding position for ten minutes," Spitfire called back, "You'll never be able to keep your wings in position for a flight. So hold it, newbie!"

What she didn't say was that after the lessons on take-off and landing, Spitfire was going to have her practice a distance flight flap - and get lunch while Dash kept it up.That part would be better as a surprise.

The second day brought a wing-sore Rainbow Dash inside one of the buildings at Wonderbolt HQ. Through the back door, oddly, but Dash wasn't going to question someone who was helping her.

Spitfire guided them through several back corridors to a long, empty room with rounded corners. She stopped by a set of ropes that dangled from the ceiling. "So do you know what a wind tunnel is?"

"Kinda?" But Dash's expression more clearly said 'no'.

"It's a tunnel," Spitfire calmly said, "Where we keep the wind."

Rainbow Dash blinked and accepted it. "Oh. Okay."

"...No, you idiot, we keep the wind in a warehouse just like we do with the clouds." Spitfire muttered something about humans being morons. "A wind tunnel has a bunch of fans on the end to simulate what it's like flying. See," she continued, "I've tried to do a Rainboom - and failed. What gets me every time isn't the speed, it's the air. Once you get to a certain point, the air can't move out of the way fast enough and it's like you're flying against a brick wall. You can't get experience dealing with that at lower speeds, and doing it at higher speeds is as likely to make you crash as it is to teach you. So this baby–" She paused to thump the wall with her hoof. "--Is designed to blow at you fast enough to simulate very high speeds."

Somehow, it all made sense to Rainbow Dash and she nodded. "And the ropes?"

"Bungie cords," Spitfire noted. "You'll be hanging from them. Safety feature so that if you lose control you won't pancake against the back of the tunnel."

And with that, they set it up. Rainbow Dash in the tunnel with bungies around her barrel, Spitfire in the control booth.

The fans started slow, humming ominously as they slowly cycled up. To Rainbow Dash's credit, she never asked if it was safe. She just gave her wings a few flaps to get her off the floor and started gliding on the artificial air current.

Spitfire's voice crackled on the intercom. "Okay, I'm going to slowly ease you up to the speed a normal Wonderbolts routine is at. Just concentrate for now on keeping yourself stable and steady. Let the wind carry you."

She did and despite the fact that two days earlier Dash had struggled to keep pace with the other Wonderbolts? She did just fine. Perhaps it was the pressure or perhaps it was not needing to try and fake the routine, but either way she held steady. So Spitfire leaned to the intercom again. "Ratcheting you up to about three-quarters of Rainboom speed."

The hum of the fans turned to a whine and then to a roar. Dash's wings pumped wildly, fighting to keep her level and on target. Her cheeks were pulled back by the wind, teeth grit with determination as she struggled.

Inside the control room, Spitfire nodded approvingly. The human wasn't too bad - this level was about where Spitfire usually tapped out, unable to withstand the strain of fighting physics. She was barely hanging on, but she was hanging on and that was better than Spitfire could do.

"Stepping it up a few notches," she said into the intercom. "The fans top out at about 90% of Rainboom speeds. Let's see how you handle that."

The throttle ticked up, and Spitfire watched her new student carefully. For a moment, she had hope that it might just be possible. Rainbow Dash was actually managing to hold her own - in fact, the increase in speed had actually helped her form a little. Her wings weren't pumping as hard and had been forced into the most aerodynamically advantageous position she could manage as physics and instinct combined. She might not be all the way there, but she was still a Rainbow Dash and that put her closer than anypony else.

Then one of the bungies snapped under the strain. Rainbow Dash - suddenly off-balance and partially unsupported - skewed into a corkscrew faster than either of their brains could register it. Spitfire slammed the kill switch for the fans as quickly as she could, but the sheer volume and speed of the wind still threw Dash every which-way. Worse, once the fans stopped there was no air flow to support her and Rainbow Dash bounced like a yo-yo on the one remaining bungie cord.

Spitfire rocketed into the wind tunnel, first aid kit in hoof. "Rainbow Dash!" Grabbing her student out of the air to stop her motion, she unclipped the cord and carefully lowered the human(?) to the ground. "Can you hear me, kid?"

"I'm fine!" A punch-drunk Rainbow Dash smiled up at her. "I went limp!"

The adrenaline drained away and Spitfire let out a sigh of relief. "You scared me there, rookie. Let's get you to the medical building."

"I'm fine," repeated Rainbow Dash, who was not, and was probably going to have a number of nasty bruises in the morning. "This isn't even the worst bungie cord injury I've had!"

Spitfire hesitated for a moment, and her curiosity got the better of her. "Huh?"

Struggling to her hooves (though partially because she was initially trying to go bipedal before remembering what body she was in), Rainbow Dash cheerfully elaborated. "Back when we first got wings, I had to help Fluttershy get used to them. So I took her bungie jumping." She laughed with almost parental pride. "She kicked my ass so hard for that!"

Several seconds of staring silence later, Spitfire leaned in to support the still off-kilter Rainbow. "I'm still taking you to a doctor."

"We have got to do something about your wings." Spitfire's inspection of Rainbow Dash's wings on the third day had originally started as her trying to figure out why Dash kept leaving them dangling rather than tight up against her sides like a normal pegasus. But that had led to other discoveries. Chief among them… "When was the last time you preened?"

Rainbow Dash - being (mostly) human - reacted with predictable confusion. "That I what?"

"Preened," Spitfire repeated with the tone of an adult asking if a child had washed their hands before dinner while being able to still see the mud.

"What's 'preened'?"

It was in that moment Spitfire remembered once more that humans don't normally have wings and this Rainbow Dash was legitimately ignorant of what that entailed. "Uh. It's, uh." She stretched out her right wing to show it off. "Over time, your feathers are going to get out of alignment. Sometimes they're just a bit out of place, sometimes they need to be pulled so you can replace them, sometimes they just need a little cleaning. Preening is how a pegasus maintains their wings and keeps them in good working order."

That seemed to at least make sense to Rainbow Dash, and she nodded along thoughtfully. "So how do I do it? Can you, like, show me how you showed me how to use my wings right?"

Spitfire froze. And blushed red as an Apple. "Well, you, uh…" She twisted her head towards her wing to start - then paused. "You just… uh."

Rainbow Dash rolled her eyes. "Look, if you can't show me can you just do it for me so we can get on with things? The show's tomorrow!"

It was difficult to summarize the emotions Spitfire went through in the span of seconds: shock, embarrassment, disgust, and confusion. She finally settled on an expression that could be best described as 'cringe'. "Okay, you're human so I'm going to give you the benefit of the doubt. Preening is extremely personal for a pegasus. The only time you see one pony preening another is when it's a parent teaching their foal, or a couple. And unlike you I don't swing that way."

Rainbow Dash startled. "Wait, what do you mean 'unlike me'?"

"...You like mares." Spitfire's brow wrinkled in confusion. "At least the other you does."

"The pony me is gay?" Dash paused, falling into thought. "Am I gay? I mean, Rarity's really pretty and Pinkie Pie's cute - and let's face it, everybody's a little gay for Sunset Shimmer…"

Spitfire held up a hoof to stop her. "Right, I am not helping you unpack any of this. Even if I was crazy enough to want to, we don't have the time." She sighed heavily. "And since you're human, you've got a good excuse for not knowing something as basic as preening. In the interest of time, I'll do it for you just this once. But only once, you don't tell anypony I did it, and you stay silent the entire time. Got it? No moans or commentary or anything." She pointed a feather accusingly. "Do not make this weird. I'm just a friend helping a friend."

Rainbow Dash saluted sharply. "Yes m'am! Understood, m'am!"

Rainbow Dash made it weird.

Most of the Wonderbolts were in their places for the show as it was due to begin in less than half an hour. Everypony was warmed up, their gear was triple checked, and all were ready to leap into yet another stunning display of aerobatic prowess.

Aside from two members. Well, one member and one outsider pretending to be one. They were sitting on a bench in the locker room, listening to the rumble of the building crowd outside.

"I'm sorry," Spitfire sullenly said. "I know this was important to you - and to Rainbow Dash. And I know you tried really hard. But going from not even being a pegasus to doing a Rainboom in less than a week?" She shook her head. "It just isn't possible." She patted Dash on the shoulder. "You did your best and you should be proud of that, kid. But there's some mountains that just can't be climbed."

Rainbow Dash nodded, head hanging. "I know. And thank you for everything you've done, Captain."

Spitfire chuckled quietly. "I'm not your Captain."

Dash hip-bumped her. "I say you are."

The two shared a private smile.

Then Spitfire stood. "Well, I better go get to my position. One little filly may be disappointed, but that doesn't mean I should let everypony else that's here for the show down."

And Rainbow Dash stood, too. "Yeah. Let's go." She paused - not noticing Spitfire's look of confusion - and pulled a small blue stone on a necklace out before sighing heavily.

Spitfire felt her headache coming back. "What's that." It wasn't really a question because she feared she knew the answer.

"It's my geode," sighed Rainbow Dash. "I didn't want to have to use it, but it looks like I don't have a choice."

"The geode from human-land." Spitfire tried not to grind her teeth. "The one that turns you into a superhero."

Again, Dash sighed. "Yeah. With super speed."

Getting to positions was forgotten - Spitfire instead grabbed Rainbow Dash by the shoulders. "I've spent all my spare time for the last three days trying to teach you how to do a Rainboom and you had a magic artifact in your pocket that gave you super speed the whole time?! Why didn't you use that from the beginning!"

Confusion. And a tone of 'duh'. "Because I wanted to do it myself. The other me doesn't need a magic doodad, so I shouldn't either."

Spitfire took a long, deep breath. "If you were anypony else," she noted, "I would break every bone in your body right now. But that is the most Rainbow Dash logic I have ever heard so I'll let it slide."

She was not reassured by how happily Rainbow Dash was smiling.

But the show had to go on. After one last question. "When you use it, you aren't going to turn into some horrific half pony half human are you?"

It was worrying that Rainbow Dash had to think about that. "Don't think so. At least, it shouldn't."

That was as good as Spitfire was going to get, and she opted not to argue. "That'll have to do. Now - are you ready?"

Rainbow Dash saluted. "Ready and raring to go, m'am!"

Spitfire gave her a sharp nod - and then they headed out to the field.

What followed was a stunning display of aerobatic prowess and the embodiment of pegasus skill that wowed audiences and made the press rave. Spitfire just called it Routine 7Δ.

Rainbow Dash, on the other hand, had no words for it. It was her first Wonderbolts show and she was entranced. If it hadn't been for Spitfire anticipating that reaction and leaving Fast Clip to prod the rookie, Dash would certainly have missed her cue. Fortunately she did not and took off at the right moment and in the right direction.

The stunt itself was, ironically, very simple. Dash just had to fly in a straight line parallel to the ground. Two Wonderbolts - Spitfire and Thunderlane, in this case - flew a twisting double helix around her, leaving bright contrails in their wake. And at the designated spot, the two other fliers broke off at sharp 90 degree angles to clear the path.

Rainbow Dash smiled.

Her geode glowed.

And the world became a rainbow.

Even as the world around her rippled with color and the wind whistled like a freight train, Rainbow Dash couldn't help but laugh with giddy joy. It never got old - the feeling of power and freedom as she shattered the sound barrier was unlike anything else. She wanted to go forever, streaking through the skies and playing with the wind. But she had a task, and part of being on a team (even if temporarily) was that you did your part. So reluctantly Rainbow Dash slowed once she hit her second mark, curved around, and glided in for her designated landing. (The landing was clumsy, but she managed to stay upright.)

Spitfire joined her there a minute or so later, coming down much more smoothly. She, too, was smiling. "You pulled it off, newbie. I was worried something would go wrong at the last second but despite you being Rainbow Dash, nothing exploded that wasn't supposed to."

Dash nodded - then stopped. "Hey. What do you mean by–"

"Rainbow Dash!"

A small orange Rainbow-seeking missile came streaking in and hit Dash right in the chest. It was only through years of practice that it became a familiar hug instead of a bowled-over pile of pony.

"Hey squirt!" A hoof fuzzled Scootaloo's already mussed mane. "I take it you saw that?"

"DID I?!" Pure joy radiated off the filly - and even Spitfire couldn't help but smile wider. Scootaloo quickly tried (and failed) to compose herself. "But it isn't important that I saw it."

Her parents - a lean pegasus and a stocky earth pony - approached at a more leisurely pace than their aggressively enthusiastic daughter.

"Now that was a right banger," announced her father, accent thick as marmite. "Don't think I've ever seen anything like that!"

Her mother was a bit more soft-spoken, but only because her father shifted the scale so high. "It was very impressive. I can see why Scootaloo insisted we should see it. It kind of reminded me of–"

Her husband cut in. "A cu bird!" Excitedly, he turned to his wife. "Crikey, you're right! The plumage on them's about a match for Rainbow Dash's mane, and when they fly–"

As the two excited parents started talking gibberish and their daughter watched with joy, Spitfire sidled up to Dash. "You know," she noted quietly, "You were part of a Wonderbolts show. That means you're a Wonderbolt now."

Dash simply shrugged. "Rainbow Dash already is."

"Yeah, but now you are." Spitfire gave her a little nudge. "It's tradition for a new Wonderbolt to get a nickname. Your counterpart's is Crash, because at her first practice she went head first into a trash can." That pulled a snorting chuckle out of the sometimes-human. "I think you've earned one of your own. I'm gonna call you… Crutch. Since you needed that doodad to perform."

Spitfire smirked - but that quickly faded as she remembered how the pony Rainbow had reacted. She braced.

Rainbow Dash considered it for a moment. And then grinned. "Awesome."

Author's Note

Did you know that this is the first story on the site with human Rainbow Dash and pony Spitfire? All the other ones with both tagged are for the human Spitfire.