Altering Harmony

"Oh yeah, baby," Rainbow Dash grinned as she did somersaults in the air. "Sky's all clear in 6.5 seconds flat! New record for me, woohoo!"

"Hey there, Rainbow Dash!" a familiar voice caught her attention as she whirled around to see Thunderlane, a pegasus friend of hers. "Wanna race?"

"Of course!" Rainbow replied as her eyes sought out a proper path for the race. "First one to the top of Sugarcube Corner wins!" She zoomed past Thunderlane, who flapped his wings eagerly as he followed her.

"Nothing like a good old race after conquering my record!" Rainbow smirked, glancing over her shoulder to see where Thunderlane was. As expected, he was way behind. "Hah, no one can beat the awesome Rainbow Dash!"

She darted through the open air - thanks to her superior sky-clearing skills - and was still far from the finish when suddenly she was knocked over by a smokey, purple cloud and began to plunge downward.

"Huh?" Rainbow Dash was halfway to the ground before she recovered her senses and flew back up as quick as she could, only barely managing to once again gain the upper hoof in the race. As soon as she was certain that Thunderlane wouldn't catch up easily, she relaxed and glanced back to see that the purple cloud had disappeared. Sighing in relief, she hummed a tune to herself as she raced toward Sugarcube Corner, only to be caught by surprise once again when a similar-looking cloud got in her way.

"Is that a... rain cloud?" Rainbow Dash was confused as she began to fall again. "Whatever, I'm not gonna let it ruin my race!" Before she could rise up again, the cloud knocked her even further down. "What the hay?"

Bam!

Rainbow Dash's head hit solid ground as through her blurry vision, she saw that Thunderlane was approaching Sugarcube Corner. Unwilling to accept defeat, she tried and tried to get up, only to be knocked down each time by another cloud.

After several more tries, Rainbow collapsed, finally giving up. "I... can't... do it," she panted heavily as, to her horror, Thunderlane reached the designated finish.

Miserable about the first defeat she'd ever suffered, she began to lose consciousness. It was only until the Cutie Mark Crusaders came into view that she resisted the urge to do so, instead focusing on them.

"Rainbow Dash!" Scootaloo exclaimed, helping her idol get up. "What happened? Are you hurt?"

As she rose to her hooves, Rainbow Dash shook her head. "I honestly don't know myself, Scootaloo. I couldn't win the race."

Scootaloo gasped. "You... lost a race? Impossible! You're Rainbow Dash! You've never been beaten before!"

"Not until now," Rainbow sighed, turning away.

"Come on, Rainbow Dash! Even if you raced a Wonderbolt, you wouldn't lose! Ever!"

Rainbow Dash shrugged and slowly walked away, her head lowered in shame.

"What's up with her?" Apple Bloom tilted her head. "She ain't like that, y'know, to just give up on a race."

"Something's definitely wrong!" Scootaloo told them urgently. "This isn't Rainbow Dash! We have to get to the bottom of this! Cutie Mark Crusaders Rainbow Dash Investigators is a go!"

"I'm sure she's just having a bad day," Sweetie Belle suggested. "Everyone has a limit, you know."

Scootaloo shook her head firmly. "Never. Rainbow. Dash."