Chapter 1
Rainbow Dash opened her eyes blearily, wondering what time it was. She looked around her and saw only darkness. Not even the moon shone in the sky. Rainbow closed her eyes again. She tried to reach down and fluff up the cloud that served as her pillow, but her hoof felt only hard ground.
Ground?
Rainbow Dash jolted fully awake and leaped onto all fours, surveying her surroundings. It was a cave. Dark, damp, and full of dripping stalactites. What was going on?
Then, in a single moment, everything came rushing back to her. The wedding. Princess Cadence turning into a changeling. The hoards of changelings raining down from the sky. And then, when she had been fighting the changelings alongside her friends, Rainbow had been grabbed from behind and knocked out with a precise hit to the head.
What about her friends? Were they worried about her? Rainbow wondered if they managed to beat the changeling army without her. And what about Queen Chrysalis?
So many unanswered questions, but for now, Rainbow had to figure out how to escape this cave. Rainbow Dash squinted into the darkness; the cave seemed to go on forever in either direction. The walls were about fifteen feet apart, the ceiling nearly thirty.
The cavern was dark, but not completely pitch black. A slight glow shone from the right cavern.
"That light has to be coming from somewhere." Rainbow muttered to herself. She opened her wings and took off, soaring down the tunnel as fast as she could go.
She tried to imagine herself as Daring Do, searching this musty old cave for the legendary temple made entirely of golden bricks. Rainbow could just imagine the title: Daring Do and the Lost Temple of Gold.
Sadly, this wasn't a book, and there were no golden buildings awaiting discovery in this seemingly endless cave.
Rainbow Dash flew on, hoping against hope that she would find a way out of this terrible prison.
Suddenly, she heard a shout below her, and felt something wrap around her ankle. Rainbow Dash was pulled to a sudden stop and yanked roughly to the hard, unforgiving ground.
"Well lookee here," said a familiar voice. "Looks like I caught myself a changeling."
"Applejack?" Rainbow Dash felt a spark of hope blossom inside her. "It's me! Rainbow Dash!"
The pony squinted at her in the dimness. "How do I know you're not a changeling pretending to be Rainbow Dash?"
Rainbow shook the rope off her foot and glared back. "Well, how do I know that you're the real Applejack?"
"Do you know anypony else that can lasso you to the ground like that?"
"Good point. Well, how am I supposed to prove that it's the real me?"
Applejack thought for a moment. "How did you get yer cutie mark?"
"By doing the coolest, awesomest sonic rainboom ever, duh!" Rainbow Dash replied, grinning.
"Ok." said Applejack. "I believe you. Now do you have any idea what's going on around here?"
"As far as I can figure, I was knocked out during our fight with the changelings and they imprisoned us here." Rainbow said.
Applejack nodded. "The ruffians grabbed me from behind. I wonder if our friends are looking for us."
A scary thought occurred to Rainbow Dash. "I wonder if they even know we're missing." she said.
"What do you mean? Of course they-" she stopped suddenly. "The changelings."
"They could pretend to be us and no one would ever know!" Rainbow Dash exclaimed.
"All the more reason to get out of here." Applejack said. "Do you think you could carry me as you fly?"
"I can try." Rainbow said. She hooked her hooves beneath Applejack's armpits and flapped her wings, slowly rising off the ground. It was harder to stay aloft, but not too hard. In no time the pair was zooming down the tunnel towards the source of light.
It was mere minutes before they reached it. Rainbow Dash set Applejack down and they both stared in amazement at the glowing crystals set into the walls around them.
"Enjoying the view?" the voice came from above them. Rainbow dash looked up to see a palace guard smirking at them through a manhole-sized hole in the ceiling. It was crossed with bars.
"Can you help us?" Applejack called to the guard.
He laughed. "Help you? Why would I help you, when I went through so much trouble getting you down there?"
"You're a changeling!" Rainbow Dash shouted. She flew up to the hole and began bucking at the bars. They wouldn't budge.
"Well duh," he smiled at her feeble attempts. "And you are our prisoners. Shining Armor may have banished Queen Chrysalis and many of our brethren, but three of us managed to fool the banishing spell. And two of us," he glared down at Rainbow Dash. "Are impersonating you two."
Rainbow Dash glared back defiantly, but, realizing that her attempts were in vain, flew back down the the ground to join Applejack.
"If all the other changelings have been banished," Applejack yelled up at him. "Then why are ya'll still here?"
"Queen Chrysalis had to have a plan B in case her original plan failed, so she chose her three best to carry out a special task."
"And what task is that?" Rainbow Dash spat on the ground.
"Why, didn't you hear?" he grinned menacingly. "You two are going to kill the bride." The changeling left without any more explanation.
***
Applejack paced around the room, trying to think of a plan. "Cadence and Shining Armor will want to have the real wedding as soon as possible, and we've been in here for about a day, so we can't have more than a few hours."
"I was going to do a Sonic Rainboom!" Rainbow Dash lamented.
"We need to find a way to break out of here and save everypony, but how?"
"It was going to be the coolest! The captain of the Wonderbolts is going to be there!"
"Rainbow!" Applejack growled. "Would you stop worrying about your precious Sonic Rainboom and help me think for a minute?"
"Oh, right." Rainbow said sheepishly. "Sorry."
Applejack sighed and looked up at the hole in the ceiling. "We have to figure out how to get those bars off."
Rainbow Dash looked up, and an idea occurred to her. "You know what, Applejack?"
"What?"
Rainbow steeled herself and launched herself towards the ceiling with all her might, flapping her wings as hard and as fast as they would go. She hit the bars at lightning speed, breaking them as if they were made of plastic. Rainbow dash flew down through the hole again and grinned.
"You should never underestimate me."
Applejack looked up at the hole, now open for them to fly through. "Rainbow, you're a genius."
***
The changeling impersonating Rainbow Dash stretched her wings, pretending to prepare for her "Sonic Rainboom". The changeling still had no idea what exactly a Sonic Rainboom was, but apparently it was scheduled for after the vows, so she wouldn't need to do it anyway.
The changeling pretending to be Applejack was in the kitchen, trying to copy the earth pony's recipes down to the pinch. She had a much harder job, because if something tasted wrong, then their whole cover could be blown.
These stupid ponies think they're safe, the changeling thought. They think that we've been defeated. Well, they have another thing coming.
***
Rainbow Dash and Applejack raced through the streets of Canterlot towards the castle. They had emerged from the cave to find themselves in one of the guard posts surrounding the border.
"According to these posters," Rainbow said to Applejack. "The wedding is going to start any minute!"
"We have to hurry! Those changelings plan to kill Cadence at the altar!" Applejack raced on, with Rainbow flying beside her.
The two ponies arrived at the castle and dashed to the bridesmaid's changing room, where only a few days ago they had been so excited for the wedding. Rainbow Dash and Applejack kicked open the door to find Fluttershy, Twilight, Rarity, Pinkie Pie, and... themselves.
"Double Rainbow!" Pinkie said happily.
"What the..." Twilight looked between the four ponies, confused.
Applejack narrowed her eyes when she saw the changeling wearing her bridesmaid dress.
"I've never been a fan of fancy dresses," she said. "But that one is mine."
"These two are impostors!" Rainbow Dash announced. "They're changelings!"
"Us?" The changeling Applejack replied. "Changelings? You guys are the changelings!"
"Oh yeah?" the real Applejack glared at her changeling-self. "Then how come we've been shut up in a cave all day?"
Rarity, Fluttershy, and Twilight stared at the duplicates, unsure what to say. Pinkie pie was at a loss of words for once.
"Give it up, changeling." The changeling Rainbow Dash said to the real Rainbow. "We know who you really are."
"How did you get past the banishing spell?" Twilight asked. Rainbow Dash looked at her, expecting her to be looking at the changeling, but instead, she was looking straight at her.
"You- you think I'm a changeling?" Rainbow Dash felt a lump form in her throat. Her friends, her best friends, couldn't tell the difference between her and a fake.
Twilight winked. "'Course not. I just had to buy some time," she turned towards the changelings. "So I could do this!"
Her horn glowed with magical energy, and immediately the changelings revealed their natural form; hideous black monsters with long sharp fangs and glowing blue eyes. The one that had been impersonating Rainbow Dash had translucent blue wings.
"No!" The changeling that had formerly been Applejack cried. "The race of the changelings will prevail!"
"Not this time." Applejack said. The changeling tried to run out the door but Applejack was too quick for her, lassoing her to the ground before she even reached the hallway.
"You will pay." said the winged changeling. "You will all pay." With one hoof, the changeling kicked open the window and flew out into the open sky.
"Get back here!" Rainbow Dash launched herself out the window after her.
The changeling flew for all she was worth but it was no use; Rainbow dash was too quick. Within seconds the two were flying side by side.
"You could join us." The changeling grinned, it's fangs glinting in the sunlight. "You could help us in our quest for glory, and in return, you would receive all that you desire."
Rainbow couldn't help but chuckle. "You knock me out, stick me in a cave, and threaten my friends, and that's the best you can do? Have you even heard about the elements of harmony?" Her gaze hardened, and she glared at the changeling. "Because I'm the element of loyalty. And I'll never abandon my friends." And with that, Rainbow Dash flew straight into the changeling, causing both to tumble to the ground.
The changeling landed hard on the pavement, but Rainbow Dash regained control right before impact, landing lightly on the ground.
"You deliver a message to that queen of yours." Rainbow Dash said harshly. "You tell her that if she ever threatens me, or anyone I love, ever again, then she had better be prepared for a world of hurt." She leaned close to the changeling until they were face to face. "Got it?"
The changeling nodded quickly and tried to fly away, but Rainbow Dash stepped on it's wing, causing it to cry out in pain.
"Now let's get back to the castle so you can be banished properly," she said. "I've got a wedding to attend."
***
Everypony in the room watched as Cadence walked down the aisle, looking stunning in her wedding dress. Rainbow Dash breathed a sigh of relief, glad that the changelings were finally gone. It hadn't been too hard to track down the third changeling, and after Twilight had banished them all, Applejack had explained to the other ponies about their imprisonment in the cave.
The happy couple finished their vows and exchanged rings. Rainbow wondered what would have happened if she and Applejack had not escaped from the cave and saved the day. She chose not to dwell on it.
Rainbow Dash was so caught up in her thoughts that she nearly forgot to perform her famous Sonic Rainboom. With a reminder from Princess Celestia, she was pulled from her thoughts and launched herself into the sky, reaching maximum speed within seconds. She grinned as, behind her, a rainbow explosion shook the sky. It was her best Sonic Rainboom yet!
In one day, Rainbow Dash had escaped from the changelings and defeated their evil plan B. And to top it all off, a perfect Sonic Rainboom, not to mention the fact that Cadence and her true love were now united in marriage.
"Best. Wedding. Ever!" Rainbow dash shouted.