John paced the floor of the waiting room. He hated waiting. Not all the time, since he could be a very patient person on occasion, but when it came to Sherlock, he wanted answers and wanted them now.

They had just gone chasing after a dog that Sherlock had finally located, when he collapsed. To be honest, John wasn't sure why Sherlock had taken the case of a missing dog, but there they were, sprinting after it in a nearby park. Until Sherlock had just dropped.

He was slightly ahead of John, one of the perks of having significantly longer legs, despite John's greater athletic ability, and one moment he was sprinting after the dog, calling over his shoulder for John to hurry, and the next he was crumpled in a pile of long limbs and coat. John immediately forgot about the dog and rushed to Sherlock's side, wondering what the hell could be going on, because he hadn't heard a gunshot or anything, and he'd actually managed to make Sherlock eat breakfast that morning.

Sherlock's forehead was bleeding a little where he must have hit his head as he fell, but otherwise looked fine. Pale, definitely, even more so than normal and when John stuck his fingers to Sherlock's neck, his pulse was thready.

That was when he called for an ambulance, realizing this wasn't just something he could fix at home.

He didn't genuinely start panicking until they strapped Sherlock onto a backboard, stuck an oxygen mask on his face, and loaded him into the ambulance.

He didn't wake up on the way to the hospital, and John was forced to remain in the waiting room. Waiting. Endlessly. John had sat through long aeroplane flights and nights that seemed endless before the sun finally decided to peek out, but this was by far the worst waiting.

"John Watson?"

John's head snapped up. "Yes?"

"I'm Mr Holmes' doctor, Doctor Coleman. I understand you're a doctor as well?"

John nodded. "You can just call me John. And Sherlock."

"Alright," he said, nodding briefly and glancing down at his notes. "Why don't we take a seat and discuss Sherlock then. He insisted that you be told anything first, and then that you tell him."

John breathed a sigh of relief. "So he's awake?

Doctor Coleman nodded. "He's been agitated, which I gather is usual for him. There are extensive notes in his chart."

John shook his head. "He mostly just likes making things difficult."

Doctor Coleman smiled. "Well, he's been relatively cooperative so far. We've done an ECG, and there seems to be some abnormal rhythms."

John nodded.

"There also seems to be a bit of fluid in his lungs. Has he been complaining of being ill lately, showing any symptoms of an infection?"

John bit his lip, but shook his head briefly.

"He's not very forthcoming about that sort of thing. He usually works until he falls asleep on his feet. He insists that his immune system is superior to any one else's, and that he can't get sick." John smirked. "You should see him when he has a cold." He looked up. "Is that what this is? Sherlock's ill, maybe pneumonia, and he just kept pushing himself until he couldn't go any further and collapsed?"

"It's possible," Doctor Coleman conceded. "But the specific cause of him passing out was from an arrhythmia that led to his oxygen saturations dropping."

John frowned. "And what caused the arrhythmia?"

The doctor shook his head. "We're still running some tests. Nothing like this has happened before?"

John shook his head. "Sherlock's done a lot of things, been shot, stabbed, passed out from low blood sugar, but I've never known him to have a heart arrhythmia."

The man examined John and nodded.

"You can see him now if you'd like. We're going to do an echo soon, and he's scheduled for more tests in the morning."

John stood up and shook the doctor's hand. "Thank you," he said.

The man smiled a little bit.