A/N: Thanks to everyone for the great response so far! You've made writing for the MacGyver fandom a pleasure :)

The text from Bozer had been brief and alarming: Mac 911

Now, less than twenty minutes later, Riley was striding through automatic doors into a gust of air conditioning that made her shiver. She turned a corner and found herself in an ER waiting room she wished she didn't know quite so well.

A quick scan of her surroundings found Bozer sitting in a corner by a fake potted tree. Riley headed for him at once, even as her blood chilled at the expression on his face. He stood when he saw her approaching.

"What happened?" she asked, reaching out to grasp him by the shoulders. She'd tracked his phone to the hospital, but hadn't wanted to waste time searching for any additional information.

"Mac's shoulder got infected."

Riley frowned, her nose wrinkling.

"I got an infection when I had my wisdom teeth taken out," she said. "My mouth puffed up and it hurt like hell for a few days, but the doctors treated it and it was no big deal. If that's all this is, what's with the 911?"

"I don't know, it was more than that," Bozer said. He didn't seem to know what to do with his hands, so he crossed his arms over his chest. "Mac...I only saw him for a second, but he was unconscious. He looked...bad, Riley."

The way his voice cracked at the end told her just how rattled he was. Her momentary relief faded.

"Where's Jack?" she asked. "Does he know?"

"He's the one who found Mac. He rode with him in the ambulance, but I haven't seen him since. He's probably still back there with him."

Riley nodded, forcing herself to think. She'd brought her laptop with her, and she considered hacking into the hospital's system so she could check Mac's file. But if he'd just gotten here, there wasn't likely to be much available. Still, his intake form would be able to tell her more than Bozer had.

Before she could make up her mind, a familiar figure appeared in the doorway to the ER proper and began to approach.

Jack looked like he'd just been hit by a truck. His face was pale, his eyes wide and a little dazed. Riley and Bozer went to him at once.

"How is he?" Riley asked. Jack shook his head, glancing out over the rows of chairs in the waiting room.

"They don't know yet," he said heavily. "They had trouble waking him up, and then he was real out of it. Didn't know where he was, what was happening…" His voice trailed off, hollow.

Riley peered at him. He was scared, she realized, just as scared as Bozer. The knowledge made her heart clench in her chest.

"I don't understand," she protested. "I mean, why...? What could do this? I get that his shoulder might be infected, but - I mean, not being able to wake up? Major disorientation? That sounds more like poison, doesn't it?"

Part of her hoped it was. Poisons had antidotes. Mystery illnesses didn't.

Jack grabbed her by the shoulders, looking at her with a new spark in his eyes.

"It does sound like poison, doesn't it?" he said. "Hell, Mac's been poisoned like that already this year. Riley, you're brilliant. Call Matty; have her send a team out to Mac's house. They need to sweep it top to bottom for something that could've done this. And tell her to double down on the search for Murdoc. If he's behind this, he might still be in the area."

Nodding, Riley pulled out her phone to comply. Bozer and Jack talked quietly while she spoke to Matty, who promised to dispatch a team to the house right away.

Once the call had ended, Jack led Riley and Bozer into the ER. It was set up in a rectangle around a central station for the doctors and nurses, the walls lined with patient rooms. Jack led them into room 8, but it was empty when they entered, without even a bed in it.

Remembering what Jack had said about Mac being taken away for testing, Riley sat down to wait in one of the padded blue chairs against the wall. Bozer took the second one, and Jack paced back and forth in front of them.

Unable to stand the tense silence, Riley extracted her laptop from her bag and began hacking into the hospital system. It took less time than it should have, and she made a mental note to beef up their security later. She pulled up the file that had been created for Mac years ago, and clicked through to find his most recent information.

His intake form listed a set of vitals, his personal information, and a brief report taken from the paramedic who'd brought Mac to the hospital. Wading through the medical jargon she barely understood, Riley scanned the report for something she could make sense of.

Her eyes froze on the screen. After a long second, she tore her eyes away to look up at Jack.

"He had a seizure?" she whispered. Bozer stiffened beside her.

"He what?"

Jack rubbed a hand over his face, not looking at either of them.

"In the ambulance," he said, voice low and rough. His gaze was haunted as he glanced behind him at the spot where Mac's bed should've been. A long second dragged by, and then another. "They gave him something to stop it."

The silence that followed was thick and stifling. Riley's gut was roiling, her whole body cold.

She'd seen Mac two days ago. Just two days, and he'd been his usual vibrant, cheerful self. Sure, his arm had been in a sling, but it hadn't made him miss a beat. Hell, he'd been teasing Jack for worrying about him. How had that vital, healthy young man ended up seizing in an ambulance?

She put a hand over her mouth, blinking eyes that stung.

"Hey, hey, none of that, now." Riley looked up to see Jack crouching before her. He put one hand on her shoulder and used the other to sweep a stray lock of hair out of her face. "You know Mac, he'll be fine. He always is. He's probably already awake again, trying to turn the MRI machine into a refrigerator."

He gave her a small, encouraging smile. It might have made her feel better had she not known him too well to miss the monumental effort behind it, the fear still lurking in his eyes.

Still, it wouldn't do any of them any good to fall apart before they knew anything. So she made herself nod and give Jack a tremulous smile in return. She nudged her elbow into Bozer's side until he nodded too.

"Yeah," he said. "Mac's come through worse than this. He's probably...he's probably telling the doctors how to make brain surgery more efficient, or something."

They managed to keep up the exchange of jokes for a few more minutes, but it wasn't long before their forced good spirits dried up and they lapsed back into grim silence.

Of course, there was never really silence in an ER. Riley could hear the quiet chatter of nurses and doctors, of patients and their families. She heard the managed commotion of a new patient being brought in through the ambulance entrance; apparently some college kid who'd partied a little too hard and was puking his guts up. She heard a doctor telling someone that the fracture wouldn't need surgery, and that he could go ahead and put a cast on there. He heard someone trying to wheedle their way out of a blood draw.

Twenty minutes had crawled by before Riley heard the sound of footsteps right outside the door though, followed by the rattle of the privacy curtain being drawn back.

"Dr. Brown," Jack said before Riley had even turned around in her seat.

He rushed towards the stout, white-haired woman in navy scrubs that had appeared in the doorway. She held up a hand to fend off the questions she could no doubt sense coming, and glanced at Riley and Bozer.

"Riley Davis, Wilt Bozer," Jack said, pointing at them as he said their names. "They're good friends of Mac's, and they can hear whatever you have to say about him."

As Mac's medical power of attorney, Riley supposed Jack had the legal right to make that decision, since Mac...couldn't.

"All right," Dr. Brown said. "We're still trying to isolate the exact problem, but I've admitted Mac for further testing and care. He'll be moved to the ICU once his scans are finished."

Hearing 'ICU' was like getting kicked in the chest. Riley shot a quick glance at Jack, who had paled again.

"Hey, listen," he said. "We were thinking, if you still don't know what's wrong; there's a better than iffy chance Mac was actually poisoned. We're working on finding an antidote, but if there's something you could do to, uh, hurry the process along on this end…"

Dr. Brown's eyebrows had risen a bit, but she displayed little other reaction to the theory.

"A basic toxicology panel is already in the works," she said. "But from what I've seen, and what you've already told me, I think Mac's existing wound is the more likely culprit."

"You mean the infection?" Jack asked. "Okay, so can't you just, you know, give him some antibiotics, add water, wait for results?"

"I'm afraid it's not that simple," Dr. Brown said gently. "Mac was already on antibiotics as a precaution for his shoulder, which means his infection has likely been caused by an antibiotic-resistant strain of bacteria. I've ordered a much more aggressive course of antibiotics, and some tests to try to isolate the strain, but it's his symptoms in the meantime that concern me."

She paused, and Riley crossed her arms over her abdomen, trying to brace herself for whatever was coming next. She found herself instinctively leaning towards Jack, who wrapped an arm around her shoulders.

"Are any of you familiar with a condition called sepsis?" Dr. Brown asked. When Jack and Bozer shook their heads, she launched into what sounded like a practiced explanation. "It's a class of infection that's associated with a disproportionate inflammatory response. Its symptoms vary and are extremely unpredictable. Among other things, sepsis can cause problems with blood flow and organ function, including the brain."

"Which is why Mac..." Bozer began, but trailed off, apparently unwilling to put into words what had happened to his friend.

"I believe so," Dr. Brown said with a nod. "Again, this can't be confirmed until a few more results come in, but this is the assumption we're working under. Sepsis is unfortunately very common, although less so for someone Mac's age. Now, sepsis doesn't always affect the brain, but I think Mac is experiencing what's called sepsis associated encephalopathy, or SAE. There are a lot of theories about what causes SAE, but we don't have a great understanding of it yet, which means we mostly have to manage symptoms while we treat the underlying infection."

"Okay, but...I mean it's not fatal or anything, right?" Jack said. "You can treat him?"

"We can and will treat him, rigorously," Dr. Brown said. "But I won't lie to you; sepsis can be fatal. About a quarter of a million people die from it every year in the US alone. The fact that Mac is showing signs of SAE is especially concerning."

Riley felt as though the breath had been sucked from her lungs.

"Look, Doc," Jack said. "All due respect to your medical expertise, but I've got Mac expertise. He's tough; he's gonna make it."

"I certainly hope so," Dr. Brown said, not seeming to take offense to the confrontational tone. She was probably used to it. "Mac does have youth and previous good health on his side. But I'm afraid that even if he does survive, he'll likely still suffer from some permanent consequences."

"What kind of consequences?" Riley asked, finding her voice again for the first time since the doctor had entered.

Dr. Brown sighed, focusing on her.

"Remember how I said the causes and symptoms of sepsis are complicated and unpredictable?" she asked. "That goes for the lasting side effects too. At this point, any outcome I predicted wouldn't be much better than a blind guess."

"Worst case scenario, then."

"It's way too early to think about that kind of-"

"I'll just look it up anyway," Riley argued, lifting her chin.

Dr. Brown pursed her lips, but said, "Worst case scenario, assuming Mac lives: he suffers permanent organ and brain damage."

"Bullshit," Jack barked into the sudden silence. The other three jumped, startled by his vehemence. He might have felt worse about scaring them, but he couldn't think about much besides what the doctor had just told him. "Bullshit," he repeated, trying to convince himself as much as anyone else. "Not Mac. Not our boy. No way."

He looked to Riley and Bozer, waiting for them to back him up. Mac couldn't suffer brain damage; he was Mac. His brain could run circles around every other brain in this hospital.

But Riley's dark eyes were wide and shining with unshed tears, and Bozer looked like he was already thinking through a future without his best friend.

"Jack," Dr. Brown said, her voice low and gentle.

He flinched away from her as if she'd slapped him, and shook his head. Mac would prove her wrong. He'd prove her wrong like he'd proven so many others wrong. Until then, what did it matter what she thought his chances were? Besides, there was still a high likelihood that Mac had been poisoned, and Matty would be calling them any minute now with the name and its antidote.

Clenching his fists, Jack did his best to rein himself in, not wanting to get thrown out of the hospital for making a scene.

"We need to see him," he said, his voice at a more acceptable volume now, although still tight with strain.

"I'll have one of the nurses take you to his room, although he may not be there when you arrive." The doctor opened her mouth as if to say something else, to try to convince him to start accepting reality, but then she switched tacks. "Mac's care is being transferred to another doctor, now that he's being admitted. Dr. Rein has more experience with cases like this, and he'll explain things to you in more detail. He's very good at what he does, and he'll make sure Mac has his very best chance."

And with that, she seemed to have washed her hands of them. After bidding them farewell and expressing her good wishes for Mac, she disappeared to see to another patient, leaving behind three people whose worlds had been shaken to the foundation.

The trip through the winding halls of the hospital was a bit of a blur for Jack. The only reality was Riley's hand in his, and he gripped it tight as they followed a nurse who looked like she wanted to be there about as much as they did.

Jack's whole body felt like lead, but also charged with useless energy. There was a band around his chest, keeping air from getting in.

He'd seen Mac in a whole range of conditions. He'd seen him drunk, drugged, exhausted, giddy, even broken, bruised, and bloody. But he'd never seen Mac in the kind of condition he'd been in strapped to that ambulance gurney.

He's seizing, the EMT had said, her voice still modulated and professional but that much more urgent than it'd been a moment before. The words had been like a spear of ice stabbed into Jack, and he'd twisted around in the front passenger seat they'd made him take, straining for a glimpse of his partner. All he'd been able to see was the paramedic's uniformed back though, hear the orders he barked at the EMT.

So lost was he in his thoughts that it took him a moment to realize they'd stopped moving. He looked around, and realized they were standing outside the sliding glass door of a patient room. The privacy curtain was drawn back far enough to show that Dr. Brown's prediction had been incorrect; Mac was in there.

Letting go of Riley at last, Jack hurried into the room. He faltered at the threshold, thrown a little by the sight of his partner lying icy pale and motionless among a nest of wires and tubes. He didn't slow for long though, and soon he was leaning over Mac's bed, reaching out to clasp his good shoulder.

"Hey, buddy," he said, keeping his tone light. "I don't think all the beauty sleep in the world's gonna help you, so why don't - Mac?"

He'd been so prepared for Mac to be out cold that it was almost a shock to see familiar blue eyes blinking open in response to his voice. Relief punched him in the gut. Screw what the doctor had said - she didn't know Mac.

"Hey," he said again, smiling as Mac's eyes fixed on him. He could feel Riley and Bozer clustering close beside him, but he was entirely focused on his partner. "I see you agreed with me about the beauty sleep; that's good. You should agree with me about more things, like not taking handcuffs off of murdery lunatics."

Mac just blinked at him, eyes clouded with something that poked a sickening hole in the sudden swell of Jack's relief. The young man frowned up at him, as if searching for something. But then Mac's brow smoothed, the relief of recognition relaxing his features.

"Dad," he murmured, eyelids drooping again. "You came back."