The average human being can hold their breath for two minutes before reflexively inhaling and for three minutes before passing out. John has been under water for three minutes, five seconds. He is certainly unconscious and has reflexively inhaled by now. Science and biology do not lie but Sherlock cannot accept that fact. It is not the first time this has crossed his mind since meeting the man he had seen bound, weighted, and tossed off a bridge into the river below three minutes and ten seconds ago but it is a law of his universe that he will believe John above such laws until the evidence is before his eyes.
He does not want to see this evidence. He never does want to see the proof that John is as human as anyone else, as mortal as anyone else, but he tears off his coat and dives into the frigid water without a thought to the fleeing Foster brothers because another law of Sherlock's universe is that there is no universe without John.
John had managed to get himself mostly free before he'd lost consciousness. It's only his legs that are still bound to the bricks and Sherlock refuses to allow the word 'succumb' to enter his thoughts. All this effort though had wasted oxygen and John had to have known that. A man other than Sherlock Holmes would assume panic but Sherlock knows John had been clear headed; he never would have made it so far had he not been.
John is hunched over, hands floating over his bound feet, so his face is hidden from Sherlock's sight by the shadows in the water. All well and good for his sanity, Sherlock has to think. He brings out the switchblade he'd taken off the younger Foster and cuts John free from his bonds. He fists John's jacket with one hand and swims them both to surface and toward river bank with a speed he had not thought possible. He can see Lestrade in this distance and bellows for him to call 999.
You should get defibrillator too if you want my chance of survival to be fifty percent and not twenty five.
He throws that order out as well even though he knows that there is nowhere for one to be found. As he drags John and himself onto shore he can see that Lestrade has already vanished in search of service for his mobile. The paramedics will come with one for certain but he knows, he knows because John has taught him, that early is always best and the paramedics will take at least six minutes to get out here.
CPR, Sherlock. Twenty five is better than zero.
He has seen John save someone with CPR before. They had been climbing an electrical fence and the suspect had reactivated the thing just before one of Lestrade's new recruits could clear it. John had been the one to hold Lestrade back until Sherlock and another Yarder had deactivated the fence and apprehended their murderer. When Sherlock had returned he'd found Lestrade attempting to direct the paramedics to their location while John breathed into the fallen man and pumped his chest. Thirty compressions in the centre of the chest followed by two breaths were given seven times before the man had thrown up and had started breathing on his own again. Sherlock had found himself supporting a much relieved Lestrade while John did as much good as he could. He'd been smiling brightly, Sherlock remembered. John had been in his element and had triumphed. The sense of victory was the same as the one Sherlock felt after he solved a puzzle.
John had taught him CPR that night at Sherlock's request and John had obliged despite his exhaustion and aching shoulder. They hadn't touched that gap in Sherlock's growing first aid knowledge simply because neither of them wanted to contemplate a situation in which it would have to be done. John had already faced it six months ago but hadn't been allowed near him. John had also threatened him with a field tracheotomy when he'd suffered an anaphylactic reaction four months ago and Sherlock had not doubted him.
Sherlock had refused to contemplate any situation that John would need his help like this. John had never stopped breathing on him before. The worst injuries that John had sustained at his side had never resulted in his breathing stopping. They had tried but John had always, stubbornly, even while unconscious, kept breathing.
For the first time since seeing John's determined but worried face vanish over the side of a bridge Sherlock looks at his friend. His skin is pale and waxy, his lips are a faint blue, and he very much looks like a corpse. It is the most terrifying sight of his entire life.
"John," he whispers. "I don't know what to do." This is the most terrifying sight of his life and this is the most terrifying admission of his life.
Yes you do. Breaths first in this instance, remember.
I can't do this.
Yes you can. I taught you, I trust you and I believe in you. Open the airway then two slow breaths.
He grabs John's face with renewed determination and opens his airway with a bit more force than necessary. Both breaths go in without resistance. When he places his hands, one on top of the other, on John's chest he can almost see John's hands over top of his and when he looks across from him he sees the John looking at him.
Thirty compressions. Keep a quick rhythm but make sure you let my chest recoil.
Sherlock locks his fingers and sets that metronome in his head. He counts off as he pumps John's heart, pushing hard and fast but giving John's chest enough time to come back. He finishes those and breathes into John again. Brain damage can happen after four minutes without oxygen and refuses to allow his brain to tell him exactly how long it has been since John took a breath before Sherlock gave him one. John's voice in his head tells him he's doing fine.
"If I'm doing so well," he grunts breathlessly in between compressions. "Why aren't you waking up?"
Thirteen, fourteen, fifteen, sixteen
"Don't you leave me, John."
Twenty, twenty one, twenty two
I'm not leaving you no matter what happens
Being a part of my mind palace does not count. You're already there and you always will be. I want you with me.
As I said, I'm not leaving you
He finishes the compressions and breathes for John again. Lestrade comes running down the hill and asks if he wants a hand. Sherlock doesn't answer him as he breathes into John again and starts a third set of compressions. "Breathe, John." He means it to sound much nastier than it does – he is doing what he should and John does not have the decency to respond. The desperation in his voice would be understood by even Anderson had he been here. "Just breathe."
Another set of compressions, two more breaths. He lets Lestrade take over the compressions for the next set because he fears he may crack more of John's ribs than he already has. "Please," he whispers into John's ear as Lestrade starts the fifth cycle of compressions. "Please." He has no other words. He takes to resting his head on John's forehand and wishing (he refuses to call it praying) for John to keep fighting.
"Please breathe, John. Please."
Lestrade is four compressions into cycle number six when John starts spitting up water. Lestrade and him turn John onto his side and Sherlock watches like a hawk as John forces all the water from his lungs. When that coughing turns into actual, shuddering, breaths Sherlock allows himself to shake, allows himself to feel chill of the water and the air. Lestrade says something but it takes a few moments after he hears his footsteps disappear into the distance for Sherlock to realise that he's gone to update the paramedics and direct them over here.
"John?" he shudders through both cold and uncertainty.
John's eyes slowly open. They are clear, aware, and tired. He starts to shiver and it takes him a millisecond more than it ought to inhale. "Yeah?" he manages to get out.
It probably isn't a good thing for Sherlock to haul John up off the ground and into his arms but he really doesn't care. He can always claim he was trying to warm them both up but that's a small, small part of the reason why he holds John so tight to him. John, who up until two minutes ago had been dead under his hands, hugs him back as tight as he is able. " S'alright," he tells Sherlock, voice a little steadier but still weak. "S'alright. M'alright."
"You came back." Sherlock doesn't add the 'to me' but it's there between them as obvious as a smoking gun. John tells him that he would never leave him alone like that without a fight.
"You did also ask very nicely."
Sherlock knows his expression must be wonderfully comical for John to laugh like this but the paramedics arrive and bundle them both up before he can comment on what clinically dead men can and can't hear. He wraps the shock blanket around himself gratefully and does his best to not down the warm tea in one gulp. John is being forced to lie down on a stretcher and be monitored properly and he is none too impressed about that.
They're separated at the hospital – John is headed off to a proper examination of his head and lungs and Sherlock is off for a change of clothes and a measure of how much he has been affected by the cold and the shock. It's all a bit silly really; John hadn't started to shiver until he'd started to breathe again and Sherlock had been far too busy to notice or suffer any effects. They hadn't been out in the cold for more than ten minutes.
His brain informs him that John had not been breathing for most of those minutes. There could be some damage involved there. His better sense tells him that it can't be anything too debilitating considering his quick answers to the simple questions in the ambulance and he was steady enough on his feet. Lestrade stops him from bolting out of the exam room. "Where did you come from?" he demands to cover his annoyance at being taken by surprise.
"From Baker Street," he hands Sherlock a plastic bag. "I reckoned both you and John would prefer your own clothes to hospital gowns. You're free to go, yeah?" The doctor, who looks equally as stunned to find a detective inspector in her exam room without her noticing, nods and only adds that he should be on the lookout for a cold. She only leaves the room when Sherlock pulls off the hospital gown and starts changing. Lestrade huffs in disguised amusement and averts his eyes. "Room 2703," he tells him. "They want to keep him overnight just to be safe but he's just fine."
Sherlock buttons up his shirt and waits for Lestrade to realise that he's stopped moving. Once he does and is looking at him Sherlock nods. Lestrade nods back and holds out a hand. "I did my best to look after him while you were gone," Lestrade tells him. "I know I didn't help much there but I did what I could. Same practice here."
"It helped here." It has been a long, hard battle to admit that John had been beyond anyone's help for the year he had been dead. Lestrade, Mrs. Hudson, and his brother had tried but John had closed himself off. He'd come back once he'd learned about Moran but once Moran had been dealt with...
Sherlock will never stop being thankful for whatever had made him leave the instant the way was clear and not the next day like Molly had suggested to him. He does not want to contemplate what world he would have returned to if he had.
He takes Lestrade's hand. "You have my thanks for both."
They take leave of each other awkwardly at that point –Lestrade pointedly excusing himself to call the team and Mrs. Hudson back and Sherlock openly fleeing to room 2703 with John's pyjama bottoms and t-shirt. He shouldn't be surprised to find John alive and awake in his room but he is. What is more surprising is that John has detached himself from the monitors without raising an alarm and is halfway to sneaking out of his room. He would have succeeded if Sherlock had not arrived then, too.
"What the hell are you doing?" Sherlock barks as quietly as he can and herds John back to his room. He shuts the door and grudgingly grants John his privacy as he changes.
"They were keeping you too long. I was worried something had happened."
Sherlock whirls around. John is in the midst of putting his shirt on but Sherlock can see the bruising from his and Lestrade's hands behind the gauze and tape. "I wasn't the one who stopped breathing today."
"You are the one who had to get me to start breathing again, though."
"I've already been told what happened. I was in the ambulance when you were given the report, remember?"
Sherlock in fact does not remember but he does not doubt John, who looks much more comfortable as he carefully gets himself back into bed. He reattaches the monitors and then turns the machines back on. No alarm. Sherlock leaves briefly to drag a chair in from the hallway and to steal a pillow from an empty stretcher. If John has to stay the night so will he. "You helped too," he adds after they're both as settled as they're going to be.
John is confused for a moment before it dawns on him. "Do I have my own room in the mind palace?"
Sherlock almost tells him that John is the reigning monarch of his mind palace but instead says he is everywhere. John looks very pleased with himself and Sherlock can't help but be pleased as well. He likes John's presence there. He much prefers John alive and beside him though. He does not want to live to see a day when the only John H. Watson that exists is the one in his head.
"At least when I say that I'll never leave you it's at least partly true." John hisses softly as Sherlock flinches. "Bit Not Good?"
"More than bit, yes."
"Don't be." You came back so you don't have to apologize for anything ever again.
They're quiet together for a few moments before John speaks a promise and a confirmation in one sentence. "I'll never leave you without a fight, Sherlock."
"And you're not going anywhere without being fought for." It's something that he really hadn't meant to say aloud but it's something John already knows. He's been told that it's nice for someone to have the obvious pointed out to them once in awhile so he allows this to not count as an error. What John had said had not been new to him either and it has eased him somewhat. His heart is getting in the way of his head tonight but he cannot call it a weakness right now.
John yawns. "It's nearly two in the morning. I'm going to bed. Try and get some sleep too, will you? There's no water left in my lungs so I will certainly wake up."
I'll never leave you without a fight
Sherlock promises to try his best.
"Oh and Sherlock?"