This takes place after the events of Stray Ardor and Something More?
Chapter One: Five Years Forward and Two Years Back.
5 Years Later...
A lot had happened in the five years since Spike and Scootaloo admitted how they felt about each other. Spike became the assistant manager for Donut Joe's Diner. Scootaloo had moved to Fluttershy's cottage due to her reaching the age where her hormones were out of control and staying under the same roof as her drake would cause problems. The move wasn't as bad as they had feared it would be, sure they were at opposite end of town but it only served as a minor inconvenience. As for Twilight she and Joe were engaged for a wedding in the fall.
In those five years, the strangest incident in Ponyville was when Equestria's only human: Ron found companionship in his boss, the Mayor Mare. It made sense to most ponies as they worked together and were both in their early forties. Ever since the day the alien claiming to be Rainbow Dash's dad showed up and began working as a secretary for the mayor, they've been rather close.
Rainbow Dash herself got her wish and became a Wonderbolt. Though currently she was still on the second string line-up as the custom for new recruits. It would only be a matter of months for her to be fielded for a major show.
Rarity was still Rarity albeit in her spare time she wrote the occasional Harlequin romance novel, but struck gold with her worse written, yet bestselling book: Fifty Shades of Hay. Her passion was still fashion and at this time of year she was swarmed by orders.
It was about a week before the senior prom at Ponyville High, but like most schools there weren’t any restrictions on who or what the students brought to the dance which this year was being held in Canterlot.
A certain purple dragon was being fitted for his tuxedo. Spike had changed significantly over the course of the last few years. He was about as tall as Big Macintosh and most of his child-like qualities were gone, his snout was a little more pronounced and his head spikes became more slender and translucent. He resembled a teenager for his species. As for the reason behind his change, it all started...
(Flashback)
2 Years Ago
Spike was doing some cleaning around the library. Over the course of the past week Twilight had started to notice something about the young drake and that was he was growing far more rapidly than he should be growing given that infancy for his species normally last for three hundred years. Though it wasn't his size that was growing rapidly but rather it was his skeletal structure. As if his body was growing to match his mental state or so she thought.
Still she made up her mind for her next set of actions."Spike, I'm worried about you. I think there maybe something wrong with your sudden physical change. I'd like for us to go see a doctor."
"You said that weren't any doctors familiar with dragons."
"You are correct, but there is a dragon doctor. I recently read that one would be spending a month in Equestria as part of a good will tour from Draconia and long story short he's coming to Canterlot tomorrow." Twilight rummaged through yesterday's newspaper and presented Spike with the article.
Doctor Silver Scale, Draconia's greatest medical mind as part of his tour across Equestria is taking office at The Lunar Medical Pavilion in Canterlot Saturday the...
The purple dragon glanced over the article and back to Twilight. He saw the look of worry in her eyes and with a gentle sigh. "Okay, Twilight I'll go see this guy with you and Scoots tomorrow."
Twilght didn't question the inclusion of Scootaloo, because after two years they were still inseparable. "In that case we'll leave this afternoon after I tell Joe."
The next morning the three of them were in Canterlot and more specifically The Lunar Medical Pavilion; a recently built five hundred bed hospital that specialized in other species as well as hybrids.
Scootaloo seemed nervous and Spike picked up on it. "What's wrong Scoot's?"
"Hospitals freak me out. They smell like disinfectant and death, they have a room full of jars with body parts in them, they keep blood in refrigerators and don't even get me started on the morgue." The pegasus shivered at her last point.
Twilight heard part of their conversation and only shrugged before she got directions from the head nurse on where Doctor Silver Scale had set up his temporary office.
It wasn't surprise to anyone he was set up in the rehabilitation gymnasium as it was mostly likely the only part of the medical center that could accommodate a full grown dragon.
Once the four of them opened the double doors to the room, they were shocked by the sight of the dragon doctor. He was just as long as Discord and was covered in a mixture of fur and scales and his face looked more like a lion than any type of reptile.
The odd looking drake broke the silence. "I take it; you're not familiar with luck dragons, are you?"
They were taken aback with his posh accent and refined demeanor. Twilight spoke up. "We're sorry; it's just that we've never seen a dragon like you."
He waved a claw dismissively. "I get that a lot. It's no problem my dear."
His eyes then landed on Spike. "Hello, I take it your here to see me for some kind of medical assistance."
"How did y--" Spike was about to ask an obvious question. "Yeah."
"Oh, I forgot to introduce myself. I am Silver Scale MD and you are?"
"Scootaloo."
"Spike."
"Twilight Sparkle."
Once introductions were over the draconic doctor returned his gaze to the purple drake. "Let's get to the matter at claw. I need to ask you some preliminary questions."
"What is your full name, element type and age?"
"Spike Sparkle, fire and fourteen." He answered in quick succession.
Doctor Silver Scale's expression soured at Spike's last answer. "F-fourteen?"
"Yep."
"You've reached adolescence about three hundred years early."
He stroked his beard and turned to the younger dragon's companions. "I need to run some test on Spike. It shouldn't take long. Could you two please wait outside?"
Twilight and Scootaloo left the room worried for Spike’s well being. The two of them waited in the lobby and were approached by a tan coated earth pony in a lab coat.
"Hey can interest any of you fine ladies in a used carriage." The mares looked at each other in confusion as he presented them with a pair of business cards that read: Fleetwood Brougham Carriage Sales- Alchemy Boulevard, Canterlot. "My prices will give you a heart attack, they're so low. Financing avai--" He was cut off by a security guard.
"THIS IS THE SEVEN TEENTH TIME THIS WEEK. FLEETWOOD GET OUT OF HERE!!!" The stallion dropped the stolen lab coat and took off as the hospital security trotted at full speed after him.
"Financing available!" The salespony called out as he ran from the guard.
20 Minutes Later
Spike left the doctor's office.
Scootaloo rushed over to embrace her boyfriend. "So, how did it go?"
"He said, he still needed to write down a few things and that he'll tell us all what's wrong with me."
After a few minutes Dr. Silver Scale came back and called them into his office. He stood there with a clipboard with a sheet of claw written paper attached to it and turned to Spike. "I'm sorry, but it's just as I thought; you have Agri Ignis Syndrome. It's named for what happens when fire dragons reach the end of their lives. They burst into flame and become one with the fire element, but in the case of this degenerative disease it stunts growth and speeds up the aging process."
Twilight and Scootaloo looked worried and went to comfort Spike. The older mare was the first to speak up. "Is there anything you can do?"
The doctor placed a claw softly on Twilight's shoulder. "I'm sorry, there is no known cure and the treatments are worst than the disease itself."
Spike gulped. "Okay doc. How long do I have to live?"
This was the part of the job that the luck dragon hated the most. "Not good son. I'm afraid, I'd say only a hundred years if you're lucky, that is if you exercise regularly, get a good supply of minerals and cut out any fatty foods."
The purple dragon was met with a mixture of emotions and when he finally settled on one he looked the doctor in eye and smiled. "That doesn't seem so bad."
"Your taking this rather well. If I had tol--" The dragonic doctor was about to further comment on the young drake's acceptance of such horrible news, but when he looked over at him, he noticed the orange mare was holding the purple drake in her front hooves. He now knew why Spike had taken the news so well.
(End Flashback)
"Spikey, could you move your arms up just a tiny bit?" He did as he was told. "Dark purple truly looks wonderful on you darling. I love that I can match your suit to Scootaloo's dress." Rarity was pleased with her work and was even happier that the dragon and his mare had one color in common.
Spike took one look in the mirror and with that typical teenage cockiness found in males. "Damn, I look good."
After a few more minutes, some tea and idle conversation with the fashionista he left the store with his tux headed to the library to put it away and then took off towards Fluttershy's cottage to hang out with Scootaloo.