Bittersweet: Part 1
Originally from an anonpost which contained elements from the Scrubs episode "My Screw Up"
Transcribed and continued by nukeiffum

Diabetes is a terrible thing.

Rainbow Dash slammed through Pinkie Pie's window, knocking the cookie from her friend's mouth. "Pinkie! You can't! You know what the doctors said! Just one more binge could kill you!"

Pinkie looked up at her friend. Smiling with tears in her eyes, she gave a weak laugh. "It's… it's okay, Rainbow Dash. I'm… I'm not afraid." Rainbow Dash settled down to the floor, blinking at a crunching noise beneath her hooves. She looked down, a look of horror spreading over her face at all the crumbs. "And… it's… not like one cookie would make much difference now anyways."

"Pinkie! Wh… what have you done!" Rainbow Dash sped to turn the room apart, looking for that needle thing the doctors gave Pinkie.

"I already used that yesterday. I… It was torture Rainbow Dash… terrible. Haha… can you imagine it? What if you suddenly weren't able to fly anymore? What if Applejack suddenly became lame? Haha… ha… I couldn't help myself Rainbow… I… haha…"

"It's going to be okay, Pinkie! You're gonna be okay. We'll get you to the doctor. They can fix this. We can make you better."

Pinkie looked at the floor, mane hiding her eyes, laughs starting to sound more like sobs. "Can… can you do me a favor, Dash? …can… can you hold me a bit? I… I keep laughing… but… it's not working as well as it used to… haha… ha… ha…"

Rainbow Dash took a hold of Pinkie Pie. "Don't worry Pinkie Pie, I'll get you to the doctor as fast as I can, just—just stop talking okay! Save your strength, please!"

"Aha… ha…" Pinkie Pie let out a weak cough. "Hey… Rainbow Dash…? I… I…"

It was truly a beautiful day for a party.

They'd spared no expense this time, all the beautiful decorations covering the event. They'd held it outside, of course, and a surprising amount of people had come out for it. Dash could even see the balloons from here. Pinkie Pie always had the best parties, and this was no exception.

Dash usually sped into Pinkie Pie's parties with great enthusiasm, ready to play pranks on whatever unsuspecting pony that happened to walk into them. However, today was different. Instead of gliding excitedly towards the partygrounds, Dash proceeded with a slow trot. A tight knot wound itself in Rainbow Dash's stomach, making Dash feel slightly sick as she made her way towards the party.

"Thanks for coming, Dash!" Pinkie said, trotting alongside her friend as soon as she saw her. "I know you didn't want to come, which is kinda weird since you always loved to come to my parties, ready to play a prank on somepony, like the hot sauce in the punch prank! I always loved that one, it's always so funny, and you're always so funny Rainbow Dash! Even when you're kinda a grump like right now, which is fine since anypony can be grumpy sometimes, except for me, because if I was a grump I wouldn't be able to throw these super-duper fantastic fantabulishous parties all the time! And look!" Pinkie said, bouncing in her step. "You got all dressed up!"

Rainbow Dash laughed to herself. She didn't like to get dressed up, it wasn't her kind of thing. But today, she'd done it for Pinkie. "Yeah, well… I guess it's the least I can do for you."

Pinkie just smiled at her in response. But very suddenly, her expression changed to one of worry. "… listen, Dash… There's something I need you to do for me."

"Sure thing Pinkie!" Dash said as they stopped in place, surprised at Pinkie's uncharacteristically mellow response. "What do you need? I'll get it done super quick!"

"You need to forgive yourself for what happened the other day." Pinkie tilted her neck down so that she could look up at Dash, smiling at her sadly. "Dash… you've always been my bestest best best friend, and I know you tried your hardest. So… no more frownie frown face, okay?"

"Pinkie Pie…" Dash just laughed again in response, shaking her head from side to side in disbelief. "You are so… random."

"Yeah yup yuh-huh!" Pinkie said, still smiling. "So you'll try? For me?"

"Yeah, yeah… fine." Was the only thing Dash could muster, smiling back, if only so it would shut her up.

Unable to think of anything else they could say to each other, they simply stood there for awhile, sharing a moment together. But before too long it was interrupted by the sound of footsteps coming up behind them. Embarrassed to be caught in such a way, Dash lifted her head back up, smiling at her best friend Pinkie Pie. "So… aren't you going to go get started?"

"On what?" Twilight Sparkle's voice asked, from somewhere close behind her.

"On the party!" Dash turned around, grinning." Y'know, chowing down, singing songs, playing pranks, bouncing around making sure everyone's having a good time. The whole routine!"

For a moment, Twilight looked at Dash with concern. "… where do you think we are?"
Dash's smile faded as she looked at the purple pony. The way her mane was combed so neat today. The way she was all dressed up in formal wear, just like Dash was. Slowly, Rainbow Dash turned around to look at the party. At all the people who had gathered there today. The beautiful decorations, all centered around the casket, with the three balloons tied to one of its handles.

It was truly a beautiful day for a party. Only one thing was missing.

Pinkie Pie was gone.

Rainbow Dash was lounging around on a cloud, blankly staring into space. The funeral ended sometime ago, and Dash fled the scene before anypony could see her cry. After all, she was Rainbow Dash, the toughest, fastest flier in Equestria, and if other ponies saw her cry it would destroy her reputation! Rainbow Dash did what she could to hold back her tears during the funeral, but she was unable to stand it when they lowered Pinkie's casket into the ground, causing her to hideaway in this cloud ever since.

"You're so stupid Rainbow Dash…" the pony said, muttering to herself. "You're Pinkie Pie's best friend, you should've caught her sickness before it got so bad…"

With all the sweets Pinkie Pie ate on a regular basis, it shouldn't have been a surprise to anypony that she contracted diabetes. Ponies usually could handle their sugar, and it seemed that Pinkie Pie quickly burned through all the sugar with her randomness. Pinkie and sweets together just seemed normal, just like Twilight Sparkle with her books or Fluttershy with her animals. Nopony thought they needed to stage an intervention for Pinkie, and it was that mindset that caused this tragedy to happen.

By the time Rainbow Dash and the other ponies found out Pinkie had diabetes, it was already too late to heal the disease with magic. Pinkie had long past the point where she could be easily cured, hiding her illness the entire time to not make anypony worry about her.

Rainbow Dash shook the thoughts of Pinkie out of her head. What's the point in worrying over what happened in the past anyways? What happens, happens, right? It just totally wasn't in her style to dwell on the past, she was Rainbow Dash! Speeding forward into the Wonderbolts and into the future! Not letting anything or anypony slow her down!

Giving this pep-talk to herself, Rainbow Dash sped out of her cloud to do some exercises. If she spent all day moping around, her spot in the Wonderbolts would disappear! Dash flew up into the air over Equestria, reached her peak height, and then performed a nosedive straight to the ground.

"C'mon Rainbow Dash… just like always, show Equestria who's the greatest flier around here!" She prepared her wings to maneuver around the clouds to spin them around, when suddenly, the image of Pinkie Pie's frail smile came back into her mind.

"I keep laughing… but… it's not working as well as it used to…"

Dash shook her head to get rid of the voice in her head, but by the time she did she plunged headfirst into the cloud, breaking her momentum. Rainbow Dash tumbled clumsily out of the cloud and roughly planted her face into another cloud right below her. And another. And another. Before she knew it, she already hit the ground.

"Argh… what's wrong with me?" Dash muttered, throwing herself back into the sky. "If I can't pull of a simple maneuver like that, I'll never get into the Wonderbolts!" Frenetically, Rainbow Dash flew through the skies again, attempting to skillfully weave around a row of clouds.

"Can… can you do me a favor, Dash? …can… can you hold me a bit?"

Rainbow Dash repeated her previous maneuver, crashing through a series of clouds before painfully landing back on the ground.

"AAARGH! Why can't I do this!" Rainbow Dash cried out angrily. "Alright, one more time!"

She sped back up in the air, even higher than she did previously, the harsh wind stinging her eyes. She was going to do it. She was going to perform a sonic rainboom. As soon as she hit the highest a pony could possibly go, she dived right down towards Equestria. Rainbow Dash sped as fast as she could, pushing her wings to the absolute limit until she could feel the sound barrier giving way to her speed.

"Hey… Rainbow Dash… I… I…"

The sound barrier suddenly ricocheted Rainbow Dash away from the ground, launching her straight into a faraway cloud with its force.

"DARN IT!" Rainbow Dash hoofed angrily at the clouds she landed on. "Why can't I do my normal tricks? Why can't I do a sonic rainboom anymore? Why… why…"

A steady stream of rain started falling down from the cloud she was on.

"Why did the party have to end, Pinkie Pie?"