The stillness of the air was interrupted as a thunderous multicolored streak burst through the sky, whooshing above the small town of Ponyville and sending stray newspapers, leaves, hats and even ponies flying as it continued on its hurried trajectory. Traveling faster than the average eye could track it, the streak performed loop-de-loops, barrel rolls, bomb dives, figure-eights and tailslides. In a nearby field, Muffins "Derpy" Hooves, a gray Pegasus with golden crossed eyes, watched the spectacle with amazement as the streak landed with a thud not twenty feet away from her and skidded to a complete stop. The dust cloud cleared away, revealing Rainbow Dash, who slid her goggles up to her forehead and did a hoof-pump, clearly impressed with her aerial acrobatic display. "Now that...was AWESOME! Derpy, what's my time?"

Regarding her stopwatch, Derpy smiled, "Four minutes and eight seconds. You beat your last record by half."

Rainbow Dash, however, was having none of this, evidenced by her next action of furiously flapping up to Derpy's face. "What?! Only four minutes? That's ridiculous!" She had been training all day to push herself past her limits so that she could one day join the legendary Wonderbolts, the most elite fliers in all of Equestria. Ever since she could remember, it'd been her dream to one day be counted among their ranks and she wasn't about to let anything get in the way of her dream. "Come on, you-you must be reading that wrong! I either do things all the way or not at all. No halfway for me."

Derpy glanced at the stopwatch. "Nope! It clearly reads, 'four minutes and eight seconds.' Sorry."

"Give me that!" Rainbow snatched the stopwatch and stared shockingly at it. "Huh, I guess you were right after all, Lazy-Eyes. My bad." She tossed it carelessly back to Derpy, who barely caught it by sliding along the ground and ending up with a face full of dirt. Derpy spat out some dirt and wiped her face clean before looking hurtfully at Rainbow Dash.

"Actually, it's constant concomitant esotropia. Most ponies refer to it as 'cross eyes.'"

Rainbow Dash began doing stretches, not even facing Derpy. "Yeah, okay. So, are you ready to try this again?"

Shaking her head, Derpy responded, "Um, why is it I'm here again? This is the longest conversation we've ever had. How come your friends aren't here helping you out, like Fluttershy or Applejack?"

The blue Pegasus stopped mid-stretch before shrugging and noncommittedly resuming what she was doing. "Pssh, those fillies? They're all acting like little crybabies just because Twilight isn't around anymore." It irritated her that not only were all of her friends avoiding one another like a plague but were also all acting so mopey and depressed. She managed to move on with her life without breaking a sweat. She tried to get through to them, such as attempting to get Fluttershy to come out of her cottage and asking Applejack to stop overreaching with apple-bucking, but they were all so wrapped up in misery that they all forgot to live. At least Rarity seemed the least damaged. All she had was a little creative block.

"What happened to Twilight Sparkle anyway? Nopony's given us a direct answer. Some rumors here and there but nothing concrete. I tried asking Mayor Mare but she said to ask one of you and, well, none of you are talking."

Pulling back her hindleg, Rainbow Dash sighed as she felt it crack and went to work on the other one. "Well, we were in the Crystal Empire when this shadow guy King Sombra came back and captured all of us except for Twilight. Sombra said he'd let us go if Twilight gave herself up to be his queen and she agreed. Now Fluttershy's a shut-in...again, Applejack's obsessed with farm work, Rarity's all out of dress ideas, Spike's acting like a lost puppy and Pinkie Pie's always got this big weird smile on her face. They're all so bent out of shape that they're acting like it's the end of the world."

Derpy put her hooves up to her mouth. "That's awful! You're telling me that one of your best friends is forced to marry an evil king and stay his prisoner for all time? No wonder your friends are all so upset. I know I'd be too if that happened to Time Turner." The brown earth pony was one of the few friends she had, even if he insisted that he was a time-traveling alien from the planet Gallopfrey.

"Yeah it's messed up but they're all forgetting that Twilight chose to go. It's not like it was any of our faults or anything," Rainbow replied insistently, though it sounded more like she said it to herself rather than Derpy. "They should get over it and acting so guilty. All this crying and moping around is really getting old." The more she said it, however, the more that Rainbow felt the pain of not having Twilight around, making lists and asking all kinds of questions like a massive nerd.

"How...how can you be so heartless?!" Derpy yelled, causing Rainbow to jump back from the normally quiet Pegasus' sudden outburst as she practically stomped right up to her. "One of your friends gave herself up to exist in a life of unhappiness with a monster in exchange for your lives and you act like you don't even care! What's the matter with you?!"

"OF COURSE I CARE!" Rainbow roared and Derpy instantly shrunk back as the blue Pegasus began to tower over her threateningly. "Twilight sacrificed herself for us and I did nothing to stop her! It didn't matter how tough I am or how strong, I just couldn't beat Sombra or prevent Twilight from being so stupid!" She was now weeping, her shaking hooves now lying at her sides. "I...I wasn't fast enough." She plopped down on the ground and shuddered uncontrollably. With a scream, she beat her hooves at the ground, imagining that each blow raining down on the soil was being directed at King Sombra's smug face. "Ahh! You stupid bastard! I hate you, I hate you, I hate you! Why did it have to be Twilight?! Why did she have to be so selfless? We weren't worth it! I wasn't worth it! Damn it!"

For the first few minutes, Derpy could only stand there in stunned silence, watching with a broken heart at the sight of the prideful Rainbow Dash hitting the ground and sobbing before curling up in the fetal position and muttering something about Twilight being too good. Tentatively, Derpy laid down beside Rainbow and slowly wrapped her forelegs around her. The crying mare was hesitant at first but then gave then, murmuring a thank you and burying her face in Derpy's chest. It seemed that the toughest of ponies took the worst of things to heart. They try so hard to be tough that they forget what it's like to let anypony in, instead working to completely reinforce their defenses. And no power in Equestria or any universe made you put up stronger walls than the power of guilt.

Author's Note

Rainbow Dash was certainly interesting to write due to her cocky, I-am-awesome-so-nothing-phases-me attitude. I think that if something happened to one of the Main Six, she'd take it the hardest. In my experiance, the toughest people are also usually the softest.

Yes, I know, the "Gallopfrey" pun was painful. I was originally going to go with "Gallineigh" but "Gallopfrey" just sounded better.

Next time, on "Shattering a Heart of Darkness," we again return to what's going on with Twilight Sparkle and King Sombra as they spend some time together and we learn more about the enigmatic umbrum's backstory. Stay tuned.