You really didn't want to laugh, and you certainly didn't mean to laugh quite so hard.
The other ponies are so shocked they don't move.
It's Applejack who finally grabs a bucket of water and flings it at Fluttershy. And then Twilight snaps out of her stunned silence and suddenly won't stop apologizing. "I'm so sorry, Fluttershy! I didn't mean to -- I didn't -- oh, I'm so sorry, I'm so sorry..."
You're still laughing.
"Rainbow Dash!" Applejack hisses. "What are you laughing for? She coulda been seriously hurt!"
"I... I'm... sorry... sorry..." you manage, between giggles. The fact of the matter is, Twilight tried a new magic spell, something went wrong, and Fluttershy ignited.
You've never seen anything funnier in your life.
You're just relaxing in your house when you see something pink bouncing towards you. You're not even a little bit surprised that the earth pony managed to get into your sky house. Pinkie Pie always manages to show up even when you're sure the very laws of physics stand against her.
Pinkie Pie ends her bouncing right in front of you, staring you directly in the face. You draw your head back slightly. "Yeah?"
"You were a big meanypants," she says.
"You laughed at Fluttershy! Now she's all sad and she won't leave her house and I even told her I'd throw her a party because how can anypony be sad when Pinkie Pie is throwing them a party but she said she didn't want any party and I'm getting really worried, I mean Fluttershy is always kind of shy, it's right there in the name, y'know! FlutterSHY! But she's ignoring everypony and I didn't even see her outside feeding the birds at her usual time and that's just not like her at all and I--"
You know that Pinkie won't shut up anytime soon, so you cut her off. "Yeah. I'll go... apologize."
"Great!" Pinkie takes an enormous leap and disappears below the clouds. As you fly towards Fluttershy's house, you see Pinkie wandering around Sweet Apple Acres, and don't even bother wondering how she got there already.
You stand at Fluttershy's door, suddenly oddly nervous.
C'mon, you tell yourself. You're Rainbow friggin' Dash. You're 20% cooler than all the other ponies. You can do this. Just friggin' apologize.
You carefully lift a hoof and give the door a tentative knock.
No answer, not that you really expected one.
"Hey, it's me, Rainbow Dash...? Look... I'm sorry I laughed at you."
Still nothing. And then, suddenly, a terrified scream. The door bursts open and Fluttershy rushes past you.
She's on fire. Again.
Your laugh catches in your throat when you see that Fluttershy is crying in obvious pain. This is no magical fire. This hurts.
You swoop upwards and grab the first cloud you see, pulling it over Fluttershy and stomping on it until it pours out rain. The fire goes out, and you fly down to where Fluttershy lies whimpering.
"Are you okay?" you ask, extending a wing to cover her. She flinches slightly at your touch and you pull your wing back, apologizing.
"...ow..." she says quietly.
She doesn't look too bad, considering. Her mane and tail are still intact, and there are only a few bare spots on her body where the yellow coat has burned away. It looks like her wings took the worst of it, and although Fluttershy never showed the same enthusiasm for flight as you, and sometimes you honestly forgot she wasn't an earth pony, you still feel terrible. She probably won't be able to fly for a while.
"Hey, Fluttershy?" you whisper. "Hey, I'm gonna take you back to your house, okay? Don't try to move, I've got you, this might hurt a little, I'm sorry..."
Gently lifting Fluttershy onto your back, you walk slowly and carefully back to Fluttershy's house, gently placing her on her bed.
"Can I, uh, can I get you anything?" you offer lamely, not knowing what else to say or do.
"pleasedon'tleave," Fluttershy whispers.
You don't. You're not the element of loyalty for nothing.
You didn't realize you fell asleep, but you awaken to a very soft voice in your ear, so soft you're surprised it wakes you up.
"Yeah?" you say sleepily, eyes still closed. Then you remember, and open your eyes fully. "I'm sorry I fell asleep, are you okay?" You're on your hooves in seconds. "D'you need anything?"
"i'm okay, i think..." Fluttershy begins to move her wings, and a grimace of pain flashes across her face for a moment.
"Hey, don't try to move just yet," you tell her. "Your wings are in pretty bad shape."
"oh..." she says.
"Don't worry. You'll be okay in no time. And until then, if you need anything, I'll get it for you. And you won't even notice I'm gone, 'cause I'll be back in--"
"--in ten seconds flat?" Fluttershy finishes for you with a small smile.
You can't help but smile too. "Exactly! Now, is there anything I can do for you?" You're surprised to discover that you really mean what you're saying. You'd gladly do anything for Fluttershy.
Fluttershy whispers something, quietly even for Fluttershy. You can't hear it.
"What was that?"
"um... could you... maybe... if you don't mind..." Fluttershy gestures towards the bed, and you fly over the bed and gently land beside her.
"Sure, just don't tell anypony else I've been snuggling," you joke, tentatively stretching out a wing to cover Fluttershy. "Uh, is this okay? I'm not hurting you, am I?"
Fluttershy sighs contentedly. "...no... this is... nice..."
Before you realize what you're doing, you lean forward and give her a soft nuzzle, then immediately draw back, embarrassed. But Fluttershy's eyes have closed and she's smiling.