Pinkie Pie was so very, very tired.

She had woken up tired yesterday, too. She had yawned into her punch glass during yesterday's party. She had dragged herself into bed with barely a shred of energy left after the last guest had left. And with the dawning of a new day, she felt as if the sun had risen the instant she'd shut her eyes.

Thoughts of her old home floated through her mind as she fought not to fully wake up. The gloomy routines of rock farming had been her entire world for the better part of her childhood, and it had taken a multi-coloured atmospheric extravaganza to make her realize that there could be more to life than a weathered face prematurely aged from pushing rocks and meal after meal of stone soup.

At times like this, when sleep did little to purge her weariness, she couldn't help but wonder what would have happened if she'd missed seeing the Sonic Rainboom. Would she still be there, on the farm? Would her sister still have left home when she did? Without opening her eyes, she rubbed a front hoof across the faint rock-pushing callus still present on the end of her nose.

Eventually the insistent glow of sunshine became too bright to ignore, and she crawled out of the quicksand-like embrace of her plush bed and plodded over to the mirror standing against the wall opposite her bedroom door. Pinkie looked at herself in the mirror, and instantly regretted it.

Yesterday had been just the tip of the iceberg; the past few days had been particularly party-intensive, with a seemingly-endless array of reasons for her and her friends to let their hair down. The toll all that partying had taken was undeniable.

She looked terrible. Her unruly magenta mane hung limply around her face, and her wide blue eyes were ringed with rose-coloured circles much darker than her carnation-pink hide. Fatigue seemed to radiate off of her like steam off of freshly-baked cupcakes. She could count on her hooves the hours of sleep she'd gotten this week.

Pinkie violently shook her head while blowing a raspberry, briefly turning her head into a noisy pink tornado. When she stopped and faced the mirror again, her eyes were a touch brighter.

"Awww…who's being a little-miss-gloomy-hooves?" she said to her reflection. "C'mon – let's see that smile!"

She willed the corners of her mouth to rise, but the results were scarcely satisfactory. It was not her usual winning smile. It wasn't even a grin. It was closer to a grimace – maybe even a rictus.

She let her mouth flop down into an exhausted frown. Her eyebrows dropped as well, and her mane and tail drooped slightly. She trotted closer to the mirror, and put one front hoof on either side of the washbasin resting in front of it. She unceremoniously dunked her face into the cold water; the shock made her heart race. With a supreme effort, she arranged her dripping face back into something resembling friendliness.

"Ooohh…you're a toughie!" she said to the mirror, droplets scattering off her face as she spoke. "When I feel down, there's one thing that always cheers me up – A PARTY!" She spread her front hooves wide, releasing a burst of confetti from nowhere in particular.

As the colourful paper scraps settled onto the wooden floor, Pinkie stayed on her hind legs, front hooves still raised, waiting for the laughter to come. The fun, joyous, silly-filly surge of energy that helped her leave every other reveler in Ponyville in the dust.

Nothing happened. She let her hooves drop.

She took a deep breath. "I said…" She darted under her bed, pulled out a party horn, and blew a deafening honk at the mirror. "A PARTY!" Again, she felt nothing. The horn fell out of her mouth. She sat down heavily.

Why are you even still doing this, Pinkamena? she silently asked her reflection. What's the point? She scowled at the mirror. Why don't you stop lying to yourself? You know what's wrong: you're all partied out. You can jump and shout and dance and prank until pigs fly, but deep down you're all partied out. Tears streaked down her cheeks. You shoulda paced yourself. Maybe one a week – two if there's a holiday. But no – you partied and partied like there was no tomorrow. And now there isn't. You're worn out. Whatever that Sonic Rainboom put in you is used up. And what's left behind? What will they all say when they see you like this? She gritted her teeth as a bitter surge of loathing rose up from the empty places inside of her like a snake slithering out of its den.

"Gloomy-hooves..." she muttered at the mirror. "Wallflower...stick-in-the-mud..." She started to shake as her voice rose in volume. "Tired old mare...! Dull-as-dishwater party-pooper! STUPID! BORING! ROCK-FARMER!"

Outside, the sky above Sugarcube Corner filled with a shock of colour as Rainbow Dash surged into view from above. The speedy Pegasus neatly perched on the second-story windowsill of Sugarcube Corner, and pulled open the window with her mouth. She stuck her head inside, and called out:

"Hey, Pinkie...! You wanna go-ohmygosh!"

"YOU'RE WORTHLESS!" Pinkie screamed, and smashed her forehead into the mirror with punishing force; a spiderweb crack spread across the glass. "YOU'RE NOTHING!" Her face struck the glass again. Shards fell into the wash basin, revealing the mirror's wooden backing. A thread of blood spilled down Pinkie's face from a cut on her forehead. As she drew back for another strike, she finally noticed the sky-blue Pegasus staring at her in horror from the open window.

"R-Rainbow Dash! Good morning!"

Pinkie resumed her typical jolly manner in the blink of an eye. This time her forced smile was so wide it made her jaw hurt worse than her forehead. Her mane had perked into its usual frizz…except for a strand of forelock pasted to her face by the blood still oozing from her cut.

"P…Pp…" Rainbow Dash tried to speak, but her mouth felt numb; this was so much worse than walking in on Pinkie's little "party" a few weeks ago. Why me? she wondered.

"Ooooh! Are we playing a guessing game?" Pinkie's voice was almost sickeningly shrill and perky. "Let's see…starts with P…OOH! Is it PARTY?"

Rainbow Dash shook her head, and hopped into the room. Averting her eyes from Pinkie's wide, gleaming gaze, she took a deep breath and forced the words to come out.

"P-Pinkie…I saw what you did. I…I heard what you said. Did something happen? Are you okay…?" Rainbow Dash waited for an answer, but she heard nothing. She looked over at Pinkie Pie, but the pink mare had vanished…because she was suddenly right next to her. Dash yelped in shock.

"Don't tell anypony about this, Dashie! Please!" Fresh tears welled up in the Earth Pony's eyes. "I was just a little sad, is all! It doesn't mean anything! Everypony gets sad, right? EVERYPONY! I mean, if you didn't get sad, how would you know when you got happy – right? RIGHT?"

Pinkie had her front hooves wrapped around Dash's shoulders; her forehead was pressed against the Pegasus'. Dash could feel her friend's blood moistening the orange streak of her forelock, and smell her hot, perpetually-sugary breath.

"D-Don't worry, Pinkie…I won't tell!" Dash was struggling to get free now, flapping her wings and skating her hooves on the smooth wooden floor. "I promise!" Pinkie let go, and Rainbow Dash surged backward. She crashed into Pinkie's bed, and fell in a heap next to it.

"Oh, thankyouthankyouthankyou! I knew I could count on you! You'd never break your promise, would you, Dashie? After all, losing a friend's trust is the fastest way to lose a friend…" In a split second, Pinkie had scooped up Rainbow Dash, and cupped the Pegasus' face in her hooves. "…FOREVER."

"You can c-count on me, Pinkie!" Rainbow Dash forced a smile, and nodded as much as Pinkie's grip would allow.

Pinkie Pie released her, and waved her hooves for joy. "YAAAYY! You're the best, Dashie!" Pinkie gasped in realization. "We should throw a PARTY to remind everyone how awesome you are! I'll go start getting ready!" With that, Pinkie took off down the stairs like a frizzy pink cannonball.

Rainbow Dash sat on the bedroom floor curled up in a ball. She wanted to fly away, but she was shaking so badly she was worried she'd crash. Not since Rarity's confidence-crushing display of her magicked gossamer wings before the Best Young Flyer Competition had one of her friends upset her so profoundly. The burden of her new secret felt like a pair of cement saddlebags on her back.

As the party in her honour rolled on, the weight moved from Rainbow Dash's back to the pit of her stomach. Pinkie Pie was totally normal again – for Pinkie Pie, anyway. Laughing and giggling, hopping about, singing and dancing, gobbling up pastries; even the cut on her forehead was invisible beneath her dark pink mane. There wasn't even the faintest hint of the wailing, despairing, self-destructive Pinkie she'd seen before. Whatever had upset her was – apparently – gone.

But what Rainbow Dash had seen still haunted her, and she couldn't let any sign of her worries show or she'd risk breaking her promise. So she had to smile and laugh and celebrate right along with her Earth Pony friend, even though she felt like a ball of stress covered with a light dusting of hide and feathers.

As Pinkie Pie juggled a quartet of frosted petit-fours, she glanced across the room at her Pegasus friend. During the whole Photo Finish fiasco, Twilight Sparkle had proven she couldn't keep a secret when it counted, but Pinkie felt she could trust Rainbow Dash. She had barely said a thing about what she'd seen on Pinkie's last birthday, and she'd shown no sign of blurting out what she'd seen today to any of the party guests. Pinkie felt relieved that it had been Dash who had seen her outburst.

You're the one, Rainbow Dash, she thought to herself. You'll understand. You've got to. With a dramatic flourish, Pinkie dropped the miniature cakes into her gaping mouth, and gulped them down.

"Ta-DAAHHH!" The party guests stomped applause and cheered; Pinkie felt nothing.

It was after the party and after hours, and Sugarcube Corner's main floor was empty of Ponies save for Pinkie Pie and Rainbow Dash. Dash had insisted that as the guest of honour and the party organizer, the two of them would handle the cleanup on their own.

The pair tidied up the balloons, streamers and other party paraphernalia in silence for a time, but soon Rainbow Dash couldn't hold her tongue any longer. She trotted over to the archway leading into the kitchen, where Pinkie was busying herself pouring the dregs of the punch down the drain.

"Pinkie…"

The word seemed to echo. Now that the silence was finally broken, Dash wasn't sure how to continue. "Are…are you sure you're okay?"

Pinkie answered without turning around. "Of course, silly! Why wouldn't I be okay?" Her tone was slightly – just slightly – lower and slower than usual.

"You know why, Pinkie." Dash rubbed the back of her rainbow-maned neck with a hoof. "Look, I'm not all that good at all this kinda thing, but I wouldn't be a very good Element of Loyalty if I didn't watch out for my friends. And I hate losing. So if something's wrong, I want you to tell me, okay?"

Pinkie Pie's shoulders heaved for a second, and she let out a tiny whimper. "I'm not happy, Dash."

"What…?" Rainbow Dash trotted closer.

Pinkie turned, suddenly almost nose to nose with Rainbow Dash. Her eyes were shining with tears. "I'M NOT HAPPY!" she wailed, and threw her hooves around the Pegasus' shoulders. She buried her face in Dash's multi-coloured mane, and sobbed. Blindsided by the outburst, Dash could only hug the Earth Pony back.

"I TRY to be happy, Dash! I try SO hard! And I try even harder to make everypony around me happy, too. But lately I just feel so EMPTY inside! And it makes me wanna cry, but if I do then everypony will know there's something WRONG with me! And they'll just try to get the happy, silly-filly, fun Pinkie back! But I don't WANT to party, Dash! Sometimes I…I want…I just…" Pinkie collapsed against her friend, coughing out wracking sobs between gasped breaths. "I don't want to party, Dash. Oh, please, PLEASE don't hate me…"

"Pinkie…" Tears of her own stung Rainbow Dash's eyes. Her expression turned stern. "I don't hate you. Nopony hates you! Everypony loves you! And we won't stop loving you just 'cause you get a little sad! If you wanna cry, then you go right ahead!"

At a loss for words, Pinkie simply obliged. She wept in her friend's embrace for what felt like hours, unleashing emotions that had been devouring her from the inside for years. Bit by bit, the flood of tears slowed to a trickle, and finally stopped. "Th-thank you, Dash." Pinkie sniffled. "This means so much to me. I don't know what I would've done if you hadn't been there. You're the best!" Pinkie smiled a tiny – by her standards – smile.

"Guilty," chuckled Rainbow Dash, relieved to see a touch of brightness back in her friend's demeanour.

Pinkie chuckled back, but then turned serious. "I…I still don't want anypony else to know about this, okay Dash? Not yet, anyways."

Rainbow Dash nodded firmly. "I'm sure all of our friends would feel the same as I do, but a promise is a promise, Pinkie. This'll be just between us – flyer's honour!" Dash solemnly raised a hoof. Pinkie Pie's smile widened to its customary broadness, and her colour seemed to brighten. She hugged her Pegasus friend one more time as Rainbow Dash turned to leave.

Outside, the sun was creeping behind the horizon as Celestia's duties gave way to Luna's. Rainbow Dash trotted a few paces, and then took to the air. She was only just above Ponyville's skyline when she felt a twinge in her back; helping her friend had felt good, but it had also been extremely stressful.

And there was still that complex rain squall to orchestrate tomorrow, followed by the High Altitude Vertical Sprint Semifinals, and then her duties teaching Pegasus foals about proper cloud-busting techniques…Rainbow Dash shook her head.

No problem! she thought to herself. If I can do a Sonic Rainboom and catch four Ponies while pulling a thousand G's, I can handle ANYTHING! But the knots in her muscles stayed where they were.

NEXT EPISODE - RAINBOW DASH: DEPENDENCE