A blood moon rised ominously in the distant while Applejack and Rarity watched anxiously.
"It's practically flaming.." Applejack said.
"It's getting creepier by the minute," Rarity replied. "I have a bad feeling about this.. come on, let's go home! We shouldn't have venture here for some adventure."
"I object," Rainbow Dash said behind them. Twilight was sitting by her, eyes closed in agreement. Rainbow continued, "How can we give up so easily?"
"What're ya saying?" Applejack turned around, perturbed. She is not a pony who takes risks.
"Rainbow Dash," Rarity scoffed. "Stop playing cool."
"With just the four of us, what can we do?" Applejack concured.
"We haven't even tried," Rainbow sat up. "How do we know it can't be done?" She trotted closer and pointed her hoof at them. "Right now we should be carefully planning our next step!"
"Listen up," Rainbow then gestured to the fog below the blood moon. "Below this plateau is a dark castle. Fluttershy is waiting for us to rescue her there."
"Dashie," Twilight admonished. "There're something approaching us."
Startled, Applejack and Rarity clutched each other. Rainbow looked down the plateau in anticipation.
"Many odd lights," Twilight continued. "they're coming from the fog."
"Will o wisps!" Applejack exclaimed.
"Oh my Celestia!" Rarity cried.
"No, they're the torches of the devil!" Applejack added. "Quick, run!" Applejack and Rarity scuttled back against a wall before clutching each other again. "With just the few of us, we are no match for the devil's army!"
"There are no escapes.." Rarity closed her eyes. "We're doomed!"
Suddenly a chivalrous figure loomed over Applejack and Rarity. The figure sounded, "Don't be scared! I won't hurt you."
AJ and Rarity opened their eyes and gasped;
"Ha ha ha!" laughed the figure, with a limelight shining behind her out from no where.
"It's Daring Do!" cried Rarity.
"That's right," the tilt on Daring Do's pith helmet was covering her eyes. "I am the one standing by justice, the one and only Daring Do!" it was awfully obvious that Rainbow Dash was inside the costume, but AJ and Rarity seemed oblivious about the mysterious mare.
"And I am the partner of Daring Do, Masked Matter-Horn!" Twilight Sparkle said excitingly.
Rarity and Applejack watched in awe, "The legendary Daring Do... why is she here?"
"When ponies need my help, I shall appear!" Rainbow-in-Daring-Do-costume said.
"That's right," Twilight-in-Masked-Matterhorn-costume added.
"B-but, even if it's Daring, she can't possibly defeat that huge army!" Applejack pointed to the advancing bunnies with flaming tails.
"Justice shall prevail!" Rainbow readied her sword, biting it firmly in her mouth. The sword sparkled as if in agreement. "Let's go, Masked Matter-Horn!"
"To battle!" Dashie blazed toward the army with Twilight on her back.
"Daring Do, good luck!" Rarity yelled.
"Do your best!" Applejack added.
The plastic animated bunnies conjured lances out of their limbs; the whole ordeal was starting to look like a jousting match. Rainbow sliced and diced left and right, breaking their lances in 10 seconds flat while the bunnies are just sitting ducks against the calvary.
"Impressive," Rarity commented. "That's Daring Do for you."
"Go!" Applejack concured. "Destroy the scoundrels!"
As the last bunny had fallen, Rainbow saw Fluttershy trapped inside a large bubble. Fluttershy waved to her, "Daring, you really came to save me!"
"I'll get you out of there immediately!" readied Rainbow, but the ground started trembling and a menace unburrowed from the depths of the abyss. The horror started chuckling its evil laugh.
"What a huge monster," Rainbow gulped.
"Daring Do... I've been waiting for you a long time," the monstrosity stated.
"Help!" cried Fluttershy.
"Just masscaring underfed bunnies isn't any thrill," taunted Rainbow. "Finally today I can have a satisfying fight! Let us duel, with honor and glory!"
"W-wait.. this might not be the best idea," Twilight interrupted.
"Why?" Rainbow turned to her.
"We don't have enough time," said Twilight with a worried face.
"What?" Rainbow was confused.
"If you don't wake up now, you'll be late for work!" Twilight explained.
"How can this be?" Rainbow said with a sad face. "I am just now starting a match to rescue Fluttershy, then reveal my true identity to Rarity and Applejack to show them who's boss - why would we end this early?"
"Hey- Daring Do!" shouted Applejack and Rarity as they approached.
"See? Here they are," Rainbow said. "This is good; I'm in my dreams anyway. I'll take him down in two, three hits." All the while the monster just patiently stared at her. "First, let's shrink this monster."
"Ehh?" exclaimed the monster. Too late, he already (somehow) shrank. "Curse you, Daring Do! That's too guile!..."
"Evil monster, die!" charged Rainbow.
"Ya'll fine right, Daring Do?" Applejack arrived and observed.
"You're not supposed to do shrink me!" The mini monster rebuked. "This is unfair!"
"Shut it, verbose. I don't have much time," Rainbow jumped on top of the monster and stomped. "Justice prevailed!" Rainbow waved her sword triumphantly before returning it to its sheath and snatched it with her wing.
"If you have any questions, quickly ask them now!" Rainbow trotted toward the gang.
"Q-questions?" Rarity asked quizzically.
"Then, what should I do to become a hero like you?" Applejack inquired.
"No, no!" Rainbow shook her head. "Something like, ask about my true identity."
"But, isn't that a secret?" Rarity said puzzled.
"It is polite to at least ask," Rainbow replied.
"Ok.. Who exactly are you?" Rarity finally asked.
"That, is a secret," Rainbow grinned.
Rarity frowned, "See? I might as well not have asked it."
"Buuut, today I will give you guys a special offer." Rainbow prepared to take off her pith helmet.
"Really?!" Applejack and Rarity said.
"I am actually..." Rainbow stopped when her helmet was stuck. "Eh? Why can't I take it off? Horseapples, it's too tight!"
"RAINBOW-" a booming voice sounded from above.
"Oh no, your mom is calling you!" Twilight said.
"What to do..." Rainbow panicked.
"RAINBOW, WAKE UP!" Rainbow's mother called again.
"Dashie, you have to wake up now," Twilight said before flying up.
"Twilight! TWIIILIIIIGHHHT!!" Rainbow followed her up.
Erm, so just finished reading the first chapter here, and... you might first want to start by finding someone who'd be willing to preread/edit what you have so far and anything else you plan on writing. There're grammatical errors littered throughout the ~1,000 words here alone. Prereaders can also help make sure you have characters more in character than anything, and help make sure your pacing is adequate and your narrative more show than tell.
Second, this:
Since when can Applejack speak Mandarin (or whichever language that is)? I mean, I can understand if that's a reference to something like Firefly where the characters have some Chinese sayings every now and then, but there's a fundamental difference between that and this fic. In shows like Firefly, there's an explanation for why people speak Mandarin. Here, in MLP, there's absolutely no rhyme or reason for why Applejack should have Chinese characters in her dialogue. If there is a reason, than this fic may require an AU tag, because it would then imply a universe that is starkly different from the in-show canon.
Third, the picture in your narrative. Just... no. There can sometimes be good reasons to include pictures into the narrative of a story, perhaps to indicate a scene break or to give a visual of what was just described. Alas, even then inserting a picture like that into the middle of the narrative simply breaks the reader's immersion, which ultimately makes for a story that's worse off. What you have done with the picture and the accompanying narrative comes across as just lazy writing. It says to me that you didn't want to bother describing Rainbow Dash flying towards something with Twilight Sparkle on her back and looking over her shoulder. And honestly? That's incredibly lazy and very unimpressive. It's not even a difficult scene to describe, and while you may have drawn inspiration from that picture for the scene, it's kind of insulting to the readers when it looks like you assume that we can't visualize an easily visualized scene of Rainbow flying with Twilight on her back. I might also add that the picture is entirely unfitting. Rainbow Dash and Twilight Sparkle are costumed for whatever reason and flying towards an army for an epic battle. The picture is them, uncostumed (which you did point out to be fair), and Rainbow's smiling. Do you see the problem with that picture being used there, ignoring the fact that a picture shouldn't be used at all anywhere?
These have been my opinions from the first chapter alone, and I'm sad to say I'm not impressed. Everyone needs to start somewhere though, so I hope that you didn't take any of what I've said offensively as I've tried to only leave constructive criticism so that you can learn from mistakes made here and grow as a writer.
4744603 I have removed the mandarin and picture bits, since they're just easter eggs.
For this chapter I only caught some mis-use in present tense in the narration. Dialogue are kept in present tense, right? So if you say there are grammar errors throughout, please quote me example. I'd be happy to fix them.