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Chapter Text

When he was growing up, Leonard would hover over his mother when she had the flu, splint the wings of birds he found in the yard, and apply dutiful ice packs to the bruises of anyone who would sit still long enough to let him. 

Every time, it was the same. He would be relaxing, off guard, and then something would be wrong . Fever. Cough. Blood. And he would become hyper-focused, the world narrowing down to this one point of wrongness , this one point of need, where something was broken and needed to be fixed. 

And he would throw himself at the problem with singleminded determination, mouth set in a tight line and eyes narrowed as he nursed his patient back to health. And every time the problem would fade away, the fruits of his labors quickly becoming visible as the world was set right again. 

There weren’t many medical problems that couldn’t be solved in 23rd century Georgia, where the science of the Federation was more than the equal of the everyday rural maladies of country life. Still, Leonard would watch the holonews, and listen to stories, and know that somewhere, out there, people were not being saved. 

They were dying, from injuries and disease and malnutrition and a thousand other things - some preventable, some not. And when he lay awake in bed at night, he would insert himself into these scenarios - Dr McCoy, who always had a hypospray and a home remedy for any problem. 

In these fantasies, Dr McCoy saved every patient, each vision ended with a happy family embracing each other, laughing and crying in their joy. Sometimes Dr McCoy cured an incurable disease, and it was distributed to every planet in the Federation. Sometimes one of his friends (nameless, faceless beings who must be in his future) would become terribly ill, and only the great Dr McCoy could save them. 

It wasn’t that he didn’t know that no one was perfect. That no doctor could save everyone. It was just that, deep down, it would never happen to him . Every day found Leonard curled up with a textbook, a medical paper, a journal detailing the latest treatments, and the future seemed endlessly bright. 

The first terrible blow to encroach upon his glistening fantasy was disease. A young, college-age Leonard McCoy, heart clutched with ice as he watched his father give the terrible diagnosis (untreatable, 99% mortality rate, say your goodbyes), but it didn’t crush his spirits. He would find a way to treat this, cure this, there was time, there was… 

He did not cure it. Standing over his father’s coffin, a man who wasn’t truly his patient, but who he had still failed to save, Leonard’s will still did not break. If anything his passion grew stronger. This was failure. This was unacceptable. Death had entered the realm of possibility, with all its heart-rending acidic pain, and it only made Leonard’s resolve stronger. He would not let this future come to pass for anyone else. Not without throwing the weight of all his knowledge and abilities at each individual problem until there was nothing left to be done.

Time passes, certifications are earned, and the reality of Dr McCoy sees more death than he ever wants to see for the rest of his life. Still, he is good at what he does, he learns quickly, and in many ways he remains the same little boy squinting with steely-eyed determination at a stubborn injury that doesn’t want to heal. 

He becomes used to the rush of adrenaline when he sees a new patient, schools his expression into a professional veneer, makes sure the compassion that drives him every moment of the day comes out in his voice, and his hands are steady as they heal his patients. 

He finds love. A daughter even. He’s never been so happy. But then scandal. Coming home early to find another man in his home and the ground drops out from under his feet. He wants to work past it. She doesn’t. Screaming and tension and papers that sever his last name from hers. 

Joanna is too young to understand. 

He runs away. 

Space is a horrifying vacuum of hidden terrors, violent aliens, unknown diseases; gravitational anomalies. It terrifies him as much as it fascinates him, and it is as far away as he can ever get from the wreckage of his life. 

Starfleet brings him cadet James T Kirk. And Bones thinks he’s found that faceless friend from his daydreams as a child. Jim is bright and energetic and everything Bones can’t find it in himself to be at the moment. Bones is still driven by that all-consuming compassion; that drive that won’t let him look away from someone in need, but he buries himself in his work in a way he never did before. 

Jim won’t let him wallow. Jim drags him to the parties he’s never been invited to, and stays up late with him and listens sympathetically whenever Bones needs a friendly ear. 

And Starfleet brings new things to learn. Of course he’s already familiar with alien biology, but in Georgia, humans make up 96% of the population, and he has to train himself out of following the more obvious non-humans with his eyes. But he learns about new organs, differences in blood clotting, and which medicines are compatible with different species. 

He learns how to treat someone in phaser-shock, or who’s gone space-happy, radiation burns, telepathic brain damage and more. Bones sees an Andorian writhing with a broken antenna, and that same childhood drive forces his hands into action like a man possessed. In the heat of the moment blue blood and twitching antenna on sky-blue skin fade away until all that is left is a being in need of help. 

When he comes out of his emergency-haze, he’s still a little uncomfortable. A little uneasy. No matter how much he studies, he will never understand alien anatomy as inherently as a human’s and that makes him nervous. But he practices. And he excels. 

Postings and assignments come and go until he’s standing by Jim’s side on a five year mission. Five years. In space. Uncharted space, no less. 

Bones has never been so uncomfortable in his life. 

Chapter Text

At first, Bones has a grudging annoyance with the existence of Spock. He doesn’t like Vulcans, not really. Doesn’t enjoy them. They suck the fun out of life like it’s their born purpose, and walk around with superiority complexes so big they could be seen from the Neutral Zone.

Not much time passes before this grudging annoyance elevates into resentment. Compassion and empathy and the inescapable urge to do something now that forces his hands into action like they aren’t his own are such an intrinsic part of who he is that he cannot grasp the humanity of someone who cuts off all these parts of himself. 

He doesn’t understand how Spock can look on dying men under his command with such cool unconcern, dismissing their sacrifices as ‘logical’ and ‘for the greater good’. He doesn’t understand how Spock can dispassionately recommend leaving good men behind to die, simply because it is the ‘logical thing to do’. He hates the idea of someone like Spock watching Jim’s back - someone who doesn’t care if Jim lives or dies, someone who, Bones thinks to himself, probably wants command of the Enterprise, probably thinks he could do a superior job to Jim Kirk. 

Bones stews in these feelings and lashes out, and Spock gives back as good as he gets. Bones is almost surprised the first time, having assumed that Spock, utterly unaffected Spock, would simply ignore Bones’ barbs and move on, but the man always seems to have a retort at the ready, his tongue as sharp as his pointed ears. 

Jim seems to have taken an incomprehensible liking to the man, however, voluntarily spending time with him outside of work for regular games of chess. Bones asked once if Jim was doing so out of obligation, to increase his and Spock’s efficiency as a command team. Jim laughed, though his eyes were drawn, and told Bones to ‘look deeper, there’s more to Spock than you’re giving him credit for.’

Bones is eventually forced to concede that this is correct. Jim and Spock become inseparable, and the more time Bones spends around the hobgoblin, the more he comes to recognize the nearly imperceptible shifts in his expression - the tightening of his eyes when Jim is in danger, the twitch of his lips when he (banters?) with Jim on the bridge. 

The science team follows Spock around like lost ducklings, vying for his attention which he gives whenever he has a moment of spare time. Uhura sings with him, in front of the crew no less. The first time Bones saw the hobgoblin sitting there, playing his Vulcan harp while Uhura accompanied, he’d almost needed to check himself into medbay for a heart attack. 

What really turns Bones around, though, is when he realizes how deeply Spock cares for the crew around him. When someone is injured or dies under his command, Bones comes to recognize the tightness in his shoulders, the darkening melancholy in his eyes, the way he pulls back into himself, away from the rest of the crew. 

When Jim is in danger, Spock may as well be human. At least, Bones muses, compared to his normal repressed self. It gets to the point where Bones can see Spock’s tightened posture, sharp glinting eyes, hear the edge in his voice and know that Jim is in trouble before words pass between them. 

And after years of kidnappings, poisonings, telepathic attacks and inhibition-lowering spores, the sheer depth of Spock’s emotion takes Bones’ breath away some days. Somehow (he’ll never be able to put his finger on when) Spock becomes a cornerstone in Bones’ life. 

Someone he can always rely on to watch Jim’s back, keep a cool head; know what to do when they enter uncharted territory. Someone who takes Bones’ nervous banter and turns it back on him, providing him with relief from the constant stress of a starship CMO. 

Jim, Bones and Spock somehow form a triumvirate, a pyramid where each relies on the other, regardless of how much bickering passes between them. This brings a new problem into Bones’ life. Previously, having Spock in medbay was a rare occurrence, thanks in no small part to the man’s uncanny ability to dodge appointments. His visits were short, clipped, and characterized by a lack of positive emotion from both parties. 

Actually caring about what happened to the pointy-eared hobgoblin made everything a thousand times worse. Because Spock. Was. Reckless. 

Worse than Jim even, because Jim would drag Spock along on his foolhardy notions, where Spock would then make himself solely responsible for the man’s safety. While Bones appreciated this in theory, he did not appreciate all the times Spock would come into sickbay boasting a never-before-discovered poison that was collapsing his lungs. 

Bones had never gotten over his hesitancy treating aliens, not completely. He understood how humans worked, intimately. He could feel how things were supposed to feel, his intuition could guide him through an untested or risky procedure, bolstered by his encyclopedic knowledge of everything he could learn about the human body. 

No matter how many aliens he treated, the feeling was never as intuitive, and in a profession where sometimes you did everything right and people died anyway, Bones hated not having that intuition. 

But Spock … Spock was a special case. Half Vulcan. Half Human. Not exactly either of the two. There had never been another hybrid like Spock before, and for all that McCoy teased him for his pointed ears, slanted eyebrows and icy green blood, what really kept him awake at night was that he wasn’t completely Vulcan .

Sure, Spock had spent more time in medical facilities in his first few years of life than most did in their entire existence. He’d been poked and prodded to kingdom come more times than even he could count, and while this surely went a long way towards explaining his aversion to McCoy’s sickbay… there just wasn’t as much information on his anatomy as there was for anyone else on the ship. Shoot, nearly anyone else in the Federation had better medical logs than Spock, and it was just McCoy’s luck that he should be so attached to someone so vulnerable. 

Bones had had nightmares over losing people for years, but it was joining the Enterprise that really ramped up his anxiety. Actually seeing the life-threatening situations day after day, feeling the ship rock around him as he knew casualties would start pouring in, people he worked with, people he knew - kids who were just getting a start in life, veterans who never walked away from the job… 

Friends, who were too brave for their own good. He couldn’t stay in sick-bay, just waiting blind. His feet would lead him to the bridge with the same compulsion that guided his hands around the wounded, and he would stare out the view screen at whatever was trying to kill them this time. He went on away missions the CMO had no business being on, because Jim and Spock may be overly-enthusiastic go-getters who had to beam down to every planet they visited, but Bones had to go to make sure he could keep his friends safe. 

Who else was he going to trust with the task? Some orderly? So many times his presence on away missions had made the difference between life and death, between a scowling Jim in medbay and a certificate of death to be signed and delivered. 

McCoy did not like being in danger. But he learned to harden his compassion into determination, a steely resolve in the face of danger, his drive to heal repurposing as a drive to protect. This is the resolve that lets him stare down maniacs with knives to his throat, narcissists who want to torture him for some twisted experiment; entire societies intent on exploiting or killing them. 

He will protect his friends. Serve and protect. Always. 

But when the danger is over, and everyone is home, safe and sound, and there is paperwork on McCoy’s datapad assuring that everyone has passed their physical with flying colors… Dr McCoy becomes Leonard, and Leonard is scared. 

He wakes up screaming most nights, night terrors as vivid as reality playing before his eyes. He’s a doctor. He knows what a spear through the gut would do to Spock. Can picture each stage of the discoloration as Jim chokes to death from a poisoned meal. Sometimes, in his dreams, he operates. Dr McCoy, holding the lives of his friends in his hands; here to save the day. He can see every stroke of the scalpel, each tendon and bone, can smell the acrid scent of burning flesh and the tang of sterile disinfectant. 

And when they die in his hands, his friends, his closest friends, he can see every step their bodies will take to decompose, rotting and shriveling away into nothing while Dr McCoy can only watch. 

He wakes up screaming, sobbing, nauseous. He wakes up with adrenaline flooding his veins and sleep an impossibility. He thinks it cannot get worse than this. Impossibly, it does. 

Deneva is one of the low points of the five year mission. Jim is so stressed and agonized that he’s about to split in two, worrying over his sister in law and nephew, and grieving the death of his brother. Millions of lives lie in peril beneath them: untold billions more in jeopardy if they cannot stop the parasites here and now. 

And then there is Spock. Jim, after the death of his brother, comes back to the ship. A captain’s work is never done, and Spock will take care of investigations on the planet. This is what Spock does. He is reliable when all else fails; he applies himself to every job with the terrifying competency that makes him the best first officer in the fleet. 

Jim beams down. Bones is not happy about this. Jim is in no mental condition to command, though he holds himself together well. If this were anything but the most dire emergency, Bones would have him on enforced sick-leave, but there is no quarter to be found today. As he watches Jim go, Bones feels that old nervousness rise up in his gut. 

Every time they leave, he may never see them again. And he has to stay here today, has to tend to his patients instead of protecting his friends. He hopes against hope that Jim will be alright. He should have been worrying about Spock. 

The call rings out in medbay, summoning him to the transporters, warning him that ‘Commander Spock needs medical attention, now !’ and all Leonard can think is ‘not him too’ before Dr McCoy is rushing out of medbay with a team of nurses and a stretcher. 

In the empty hallways between medbay and the transporter room there is time enough for Bones to panic, to think about the dead strewn across the planet, across the galaxy from this parasite, the dead woman in medbay; the potentially untreatable monster that has now gripped his friend. 

He bursts into the transporter room, and sees Jim holding Spock - they must have beamed up together; Jim’s grip is a vice across Spock’s chest - and Bones gets a moment to see the helpless terror in Jim’s eyes before everything but Spock fades away. 

His muscles are locked in agony, and his eyes are as wide and as filled with pain as McCoy has ever seen them. It takes him a second to recognize the unguarded fear there, simply because he never expected to see it. McCoy is immediately rushing forward, taking readings and double checking when he finds things he never wanted to see. 

Spock begins to thrash, alien muscles easily overpowering human ones, and it takes three men and a hypospray to bring him down. He twitches, even in unconsciousness. 

Bones performs surgery and digs through his friend’s body to root out the invader. He cannot extract it, and the K3 indicator wavers around the top of the scale even as Spock ought to be asleep. They learn more about the parasite. They learn that it is hopeless. That it cannot be extracted, that its victims will be driven insane or die; that even Spock’s iron will can be overridden by its control. 

In the end, Jim is the one who discovers how to kill the beast. A blinding flash of light, lethal to the parasite: maiming for Spock. McCoy cannot bear to see people in pain. But it goes against his nature, to his very soul to hurt his friends. But there is no time and no options, and Spock is so sure that this is what he wants. The man marches himself inside (like a lamb to the slaughter), and with his own hand McCoy presses the button that sears Spock blind. 

In a cruel twist of fate, no more than two minutes later he learns that it was unnecessary. That he could have used non-visible light to kill the creature. That he has maimed his friend permanently for nothing. 

Spock, in full Vulcan repression mode, lets nothing slip except to voice his gratitude for being freed of the creature. Jim can hide nothing. Leonard has never seen that look on Jim’s face before - the heartbreak combined with all consuming anger, has never wanted to see it pointed at him … but he can’t bring himself to fight back. 

His fault. He swore to do no harm. He has betrayed the very essence of his own character, and it cracks him open to his core, far more than Jim’s furious betrayal ever could. He had cost his patient, his friend, his vision. 

When that vision returns, it is again through no contribution of McCoy’s. A second eyelid, apparently. Something Vulcans tended to ignore. Something McCoy had read in a footnote of a textbook long ago and forgot about. A critical aspect of Spock’s biology, and McCoy had been ignorant and useless. 

It would never happen again. 

The night after Spock makes his miraculous recovery from the Denevan parasite McCoy knows better than to try and sleep. He roots through his datapad, pulls up every scrap of information ever recorded concerning S’chen T’gai Spock, and sits down to read. 

He doesn’t sleep that night, instead pouring over every tiny detail of Spock’s biology, committing even the most mundane eccentricities to memory. The next day he all but shoves Spock into medbay so he can run a full physical. 

Every time those two idiots does anything there is always a part of Leonard, a fluttering, terrified part, that never settles down until he can run a physical. Until he has written proof in his hands that his friends are alright, that the danger is gone. 

Everything comes back normal - he’d prescribe muscle relaxants and painkillers for the clinging aftereffects if he thought Spock would take them - and Spock makes a conscious effort to nod in gratitude for McCoy’s attentions (it’s Spock’s way of saying there’s no hard feelings; he doesn’t blame McCoy for nearly blinding him on a whim) and Bones is left to pour over his newest results with fresh eyes. 

He stays up late pouring over the results of the physical. Recorded data from every medical encounter Spock has ever had. 

He runs simulations in his head and on the computer. 

He quizzes himself on obscure factoids and berates himself mercilessly for every wrong answer. 

The bags under his eyes darken and migraines pound against his skull, but the drive is under his skin now. It won’t be turned on and off in the face of danger, now, not when they’re in space, not when the danger is everywhere , everywhen. 

He gets so bad that Spock actually comes to tell him to take better care of himself (Jim has been saying this for weeks, but Jim is always a hypocrite like that), and McCoy finally takes sleeping pills to force his hyperactive mind to rest. 

The nightmares are worse. A thousand potential surprises locked within Spock’s biology, each waiting for the moment to steel the pointy-eared-elf away, each eluding even the most determined of Bones’ scans. 

McCoy spends late hours talking with Dr M’Benga, learning everything he can from the man. He runs more tests and discovers new facets of Spock’s biology that no one has discovered before. He writes them down, and keeps focusing. 

Time passes, and he is forced to make his peace with the unknown. He still studies and dreams like a man possessed, but he must accept that there are some things he may never know. Risks that will always be there. 

Spock is relieved at the waning in Bones’ determination. Bones resigns himself for the next emergency.

Chapter Text

If there’s one thing Bones likes less than being the victim of attempted murder, it’s politics. No one gives a straight answer about anything, diplomats turn every papercut into an attempted assassination, and the uniforms were designed in the torture pits of Q'onoS.

First contact politics are always a gamble, because maybe the aliens want to throw you a banquet, and maybe they want to hold a gladiator match where you prove your worth in ritual combat. Thankfully, this planet seems to lean toward the former, and Bones is tentatively hopeful that this will be a Good Mission. 

The locals are a friendly telepathic race with strange psychic powers, and they seem excited to find a new race to bond with in friendship. They seem to be open to joining the Federation, and even Jim has managed not to poison himself. 

Bones holds a fascinating conversation with one of their doctors, who explains that their race draws their strength from the collective, divvied out according to need among them. By using their psychic bond, they always know who needs the most help. A fascinating culture, especially given that they seem to retain far more individuality than these group-mind types usually do. 

The alien doctor (T’nira?) finds McCoy’s own insights fascinating as well, and she smiles before turning away to find their leader. They converse, before turning to announce their pleasure with the encounter. 

Their leader, a tall slender alien with large dark eyes announces that ‘We will be pleased to consider a friendship/partnership with the Federation/Enterprise. We are pleased to have this opportunity to develop friends/partners.’

T’nira lopes back over to McCoy, eyes bright as McCoy has to tilt his head back to meet her gaze. “We are friends/partners/equals, yes? DrLeonardMcCoy?”

Bones slips on his most affable grin, and nods. “I’d say so T’nira. And I’m very pleased to have made your acquaintance.” Her eyes glow as she smiles, and Bones winces as his head twinges. Telepaths.

A few minutes later, Bones is hovering at the edge of the party, observing the peaceful milling about of successful negotiation. 

Bones finds himself smiling, before he cuts himself off with a frown. Sometimes he thinks tension and unease is his Pavlovian response to happiness, born of a thousand turn-on-a-dime emergencies. Bones is so very tired of always being right. 

There is little warning before the pulse wave of sound slams into Bones with the force of a tidal wave. His first instinct is to crouch and protect his head from any flying debris launched by the explosion. The second is to spin on his heel and scan the field for any signs of blood, damage, injury…

The hobgoblin. 

Strewn on the ground like a broken doll, green blood fading into the grass. Bones feels his gut clench ( Is this it? Is this the time there is nothing he can do? Will he reach Spock’s side and realize it’s already too late…?) His tricorder is in his hand before he is even conscious of rushing to Spock’s side. 

He breathes a sigh of relief at the life registered by the device, and feels Kirk’s presence over his shoulder before the man even says anything. There’s tumult around him, and the buzz of the transporter under his skin, and then he’s barking out orders even as his orderlies help wheel Spock to sickbay. 

Puncture wounds, from splintered wood. Burns. Internal bleeding. Poison? 

They shift Spock onto the biobed, and McCoy watches Spock’s readings flare across the screen. There’s some kind of… juice covering Spock, and McCoy isn’t sure what it is. He doesn’t like the way it’s interacting with the man’s wounds, though. 

Someone bursts into his medbay (aren’t they one of Spock’s science team?) and runs over to him. Her eyes are wide and her hair askew, though it hardly registers through McCoy’s doctor focus. 

“Dr McCoy-”

“I’m busy, woman!”

“I know! It’s about his wounds, sir! The explosion was caused by fermented fruit from the planet - something about the energy from our transporters caused them to violently ferment and explode - that’s what’s covering the commander. We think the plants are toxic to him!”

McCoy eyes the smears of juice that haven’t been completely wiped away as the wounds were cleaned. That changes things. 

“We have a readout of their chemical make-up, sir!” The woman hands McCoy a datapad, and his trained eyes scan the information even as his nurses prep Spock for emergency surgery.

This isn’t good - Spock is allergic to some of these compounds, or at least similar chemicals. Some are straight-up toxic… this will be tricky, McCoy is sure. Still, as he glances up at the bio-bed readings, he is at least assured that Spock ought to pull through. Sure, he was critically injured now, but he’s strong enough that with treatment none of this should kill him. 

He nods to dismiss the woman who disappears, before turning around to activate the decontamination field. 

He sends a glance to a nurse - before they start operating they need to make sure Spock will be stable, that none of these chemicals will have a chance to seriously wreck havok with his biology. 

For a brief moment McCoy considers his options. They have a general anti-toxin antidote that he’s used on Spock before, but it might not be enough to cover the potentially unknown effects. Despite being all-purpose it isn’t as strong as individually treating each poison would be. He thinks it would be enough to pull Spock through, but if anything goes wrong… no, better to use the stronger treatments. 

He can’t take the chance. 

He calls for ketoprophen, levocetirizine, dichloricbenzine and tripoprophin, personally injecting each hypospray into Spock’s arm. While most Vulcans don’t have many allergies, Spock has inherited far too many from his mother for McCoy’s taste. 

That task completed, McCoy begins to operate. The wood, for the most part, is easily removed, although the splinters tig deep into Spock’s flesh, and are impossible to remove cleanly. Still, the danger is minimal, and for the moment he focuses on the larger chunks that would impede the more vital surgery he has yet to perform. 

The internal bleeding, pierced liver and bruised heart are of far greater concern. The heart in particular is refusing to pump blood as well as it should. For a Vulcan, this is terrible news. Copper based blood is tricky enough as it is - it simply doesn’t have the oxygen-carrying capacity of a human’s. No Earth mammal has copper based blood, especially in warm climates for that precise reason. 

Increased cold might help with oxygenation, but as a Vulcan accustomed to desert temperatures, Spock would need time to prepare his physiology for the shock. In this moment it would hurt more than anything. 

To compensate, Vulcans have extremely high heartrates, their hearts beating about four times per second. Right now, Spock’s heart isn’t doing that. And that means reduced oxygen to the brain. Spock is a Vulcan. Without his brain… he won’t survive. Not even life support can save a Vulcan with a damaged brain. He’d limp along for a couple days… and die. 

But McCoy can still save him. They aren’t out of time. Spock’s vitals are strong, if a bit unusual, even for him. 

They put Spock on a ventilator, shoot him up with a tri-ox compound, and he focuses on the bleeding. The bleeding would kill Spock faster than anything else, but 23rd century science quickly sews together the damaged veins and arteries, and a crisis is averted. 

Next is the liver, struggling to avoid permanent damage. The liver is when the problems start to become obvious. What should be a straightforward process is… complicated. Spock’s body does not respond the way it should. The minor discrepancies in his vitals start to become more pronounced, and McCoy stares at the discoloration and inflammation in confusion. 

What could be going wrong? 

Spock’s body is less dependent on his liver than a human’s, but if they don’t fix it now Spock won’t survive the hour. They should be able to fix it. But Spock is growing weaker, paler, skin taking an unnatural pink tint as green blood fails to circulate properly. 

They need to fix the liver. Fix it, now, and discover what’s going wrong after. McCoy orders more ketoprophen, and continues to operate. 

Spock’s breathing hitches, his heartbeat stutters. Arrhythmia. They need to defibrillate, but Spock’s body can’t take it in this state. His heart speeds up, slows down, his body clenches as it demands oxygen, demands blood. 

McCoy orders a sedative. The instant the chemical hits Spock’s system he realizes what he’s done wrong. 

No. 

NO. 

Just for a second, for the first time in his life, McCoy’s hands shake during a surgery. 

He gulps, and sees his path as clear as day. Sees the problem, sees his mistakes, sees what he must do next.

He steadies his hands. The bioregenerator does its work, with some help. His work on the liver is done.

“Close him up.” His voice is raspy, wrecked like he’s never heard it before. Chapel sends him a shocked glance, but he ignores it. She hasn’t realized his mistake. She will. “Do it. And… put him on life support.”

Yes, as little strain on Spock’s system as possible, that was it. McCoy stumbles back, hands really shaking now, and he makes his way to his office. Collapses into the chair behind his desk and drops his head in his hands. 

Spock. 

He’ll lose his medical license for this. He deserves it. 

Jim… what will Jim say? Jim’s shocked and betrayed face from Deneva flashes in front of his eyes. He never wanted to see that look again. But today, Dr McCoy deserves all the scorn James T Kirk can muster. 

He imagines what Spock would say. A fruitless exercise. Spock will never wake up to argue with him again. 

Someone barges into his office, and he catches a flash of gold. Not yet. Not him-

“McCoy! How’s Spock? You stopped operating? Will he be alright?”

Bones can’t bring himself to look Jim in the face. If he doesn’t say it, it’s not real. Schrodinger’s Spock, dead and alive. 

“Bones, answer me!”

Leonard picks his head up out of his hands and feels the tears streaking down his face for the first time. His hands are still shaking. 

“I’m so sorry, Jim.”

“Bones?” Jim hasn’t given up yet, too hyped up on adrenaline and a thousand near-death survivals to give up on Spock yet. “Bones, what’s wrong?”

“I’m so sorry,” he says again, and Jim will think he’s apologizing for not doing enough when he doesn’t understand-

“Answer me right this minute!” Kirk’s fist comes crashing down on the desk; he always gets aggressive when he’s scared. 

“It’s my fault,” he chokes, and Jim’s face becomes Josephine’s, face twisted in rage, screaming for him to getoutgetout and never come back… “I… he was having an allergic reaction to the alien juices. They were toxic to him. I gave him injections for inflammation, allergies, the like. But Jim… it was the wrong combination . Individually, all those medications are perfectly fine for Spock, but together… they’re killing him. They’re killing him, Jim!”

Jim’s eyes go wide as he processes as well as he can. 

“I shouldn’t have done it. I’d never tested all those substances at once, I didn’t know what could happen… if he was a human it would be fine but I didn’t think … I didn’t think. If I’d gone all-purpose… he didn’t have to die, Jim. He didn’t have to die!”

Leonard drops his head into his hands - he can’t bear to see Jim’s face, can’t stand to see what Jim thinks of him now - and he hears footsteps exiting the room. Alone in the confines of his office, Leonard McCoy sobs. 

Chapter Text

Time loses meaning. There are no alarms, nothing to disturb the infinite void of time inside this room. Outside, Spock is dying, Jim no doubt desperate to be glued to his side, except that there is a mission, and the Captain cannot make exceptions to his duty. 

Is anyone sitting with Spock now? Is Spock even aware enough to know? Vulcans have very active minds, even in unconsciousness… does he know if his friends are there? Can he feel any pain? Does he understand what Leonard has done to him? 

His touch telepathy… could he feel anything? Bones always tries to keep his emotions to a minimum while treating Spock to prevent his human feelings from disturbing Spock’s mental state… but he had been in shock. Perhaps… 

Spock’s heart is bruised now. It isn’t even a conscious thought - not formed with words, but images and impressions as real and tangible to Bones as the desk beneath his fingers. He can see, feel the ruined anatomy as if it was his own. 

The heart is bruised. Not pumping blood as fast as Spock’s brain needs it to. Not providing enough oxygen. And thanks to McCoy’s incompetence, Spock no longer has the strength for extra surgery. 

Bones isn’t perfect. He’s lost patients before. Looked back on past surgeries and seen other paths, better paths that he should have taken. But this is the first time… stupid. So stupid. With his own two hands he poisoned Spock, stealing his life away. 

Spock, with his gentle curiosity, and inquisitive nature. Spock who always wanted to preserve life whenever possible, who cared for Jim so fiercely and would sacrifice himself for his friends in a heartbeat. 

At some point… for all that the hobgoblin got on his nerves, there was something almost… vulnerable about him. An almost childlike emotional vulnerability and motivation, the result of a simple focus that had lasted his entire life. He was trying to learn to understand his emotions, Bones was sure of it, a little more each day. 

He was trying to learn to be a better friend, and make the people around him feel better, and there was a pure passion to help in him, untainted by the greed and jealousy that had its’ claws in so many humans… 

Somehow, Bones had grown protective of the elf. He was young, terribly young for a Vulcan and… and he always worried terribly when the idiot went off by himself or wound up on his operating table and… 

It felt like his soul was being torn in two. His most important duty, his most sacred oath… his friend… 

There was a beeping noise… he was being called? Bones managed to raise his head, scrubbing at his eyes, stinging with grit and salty tears. He fumbled for a tissue before stumbling to the door… it must be important (it’ll be Jim, demanding your resignation, sending you back to Earth to drink your life away alone forever) and startles as he comes face-to-face with T’nira. 

Of all possible visitors, he hadn’t even considered her. 

“Friend/partner/equal DrLeonardMcCoy? You are distressed.”

Bones rubs his eyes again, beyond being personally self-conscious about the red rims (if she even understood them), but unable to understand why T’nira was here, and why Jim would let her see him in his condition. 

With a startling jolt, Bones realized that Jim was behind T’nira, but he jerked his gaze away from Jim’s face before he could read anything there. 

“Yeah,” he settles for, “I am.”

“You mourn, DrLeonardMcCoy.”

He considers this. What is being expected of him? What is this? 

“My friend…” he settles, “he’s dying. It’s not… your fault. Or your people’s fault. It was an accident.” Will this ruin the negotiations? Why is she here?

“You are my friend/partner/equal. You are… with us. One. We must help/heal/share the strength of One. Where is our friend?”

Leonard straightens up, jolting. His eyes blow wide and he turns to look at Jim, who looks wrecked, but tentatively, doggedly, hopeful. 

“He’s… he’s here.” McCoy stumbles backwards, lightheaded with the new possibilities being presented by the future. “You can do it? Share your… hive strength with an outsider?”

“Not an outsider, DrLeonardMcCoy. As my friend/partner/equal you are with/connected to the One. You must remember - we formed the bond/friendship earlier today. This being is your friend/partner/equal. And so, they are not an outsider.”

The headache - the twinge he had felt while talking to T’Nira - he had accidentally agreed to be let in on the hive mind. Of course! Bones felt his head nodding in assent as he rushed to Spock’s bedside, the Vulcan’s skin still an eerie pale. “Here. He’s right here.”

T’nira nodded, standing beside Spock. Her eyes glowed. “He is… not well.”

“I know that,” McCoy snapped before he could stop himself. T’nira seemed unperturbed, and turned to face him. 

“We do not heal. We cannot… knit bone and flesh. We have only strength to offer.”

“That’s alright. That’s fine. The problem is… he’s too weak for surgery, or invasive treatment. If he could be stronger… I can fix him. I can do everything else.”

T’nira nods, and bends her head as she raises a hand over Spock’s prone form. “Then let him be well.”

McCoy watched in open fascination as the vitals above Spock’s head trembled and started to raise themselves upwards. 

“Would DrLeonardMcCoy like for his friend/partner/equal to be sustained while DrLeonardMcCoy heals him?”

“Yes! Yes,” McCoy managed, “that’ll be fine! Just… just keep doin’ that, T’nira. Nurse!”

Just like that, he could feel the doctor slipping over him, the edges fading out of his vision, the world narrowing down to the body and the instruments and his hands, reaching out, drawing him forward, flesh and bone and blood waiting to be manipulated until everything could be made right. 

Chapter Text

When McCoy is done, Spock’s breathing has evened out and his heartrate is back to its’ usual fluttering rhythm. Bones spends 30 minutes just staring at the readouts on the monitor after the surgery, unable to move, unable to accept that this miracle has happened to him. To them. 

T’nira is gone; Chapel tactfully ignores his stagnation. No one has called the captain in yet, but T’nira probably told him that Spock was doing well after she left the sickbay. Bones imagines Jim pacing outside the medbay doors - a bad habit, since it unnerves the crew, so Jim only indulges in the most dire circumstances. 

Spock’s chest rises and falls, and his vitals stay in that reassuring range where nothing needs to be changed or addressed. The green flush is back in his cheeks, and light green tints his pointed ears. 

Bones feels almost giddy with relief. 

“Dr McCoy…” Christine looks down at him, understanding but cautious. “Do you think we can let the Captain in yet?” 

Bones sends a glance to the sickbay doors, then drops his gaze to Spock’s impassive face. “Sure. I’ll… let him in.”

His feet carry him to the medbay doors, which open to reveal Kirk in the middle of pacing the halls. His head snaps to meet Bones, and he jogs the few steps to the doorway. 

“Bones! Is he… alright?”

And Leonard finds himself nodding, a smile actually touching his face for the first time since this horrid affair… it feels too soon. He ought to be grieving right now, not smiling. 

“He’ll be alright. Why don’t you come on in?”

Bones steps to the side and Jim barrels in, making a beeline to Spock’s side. Bones watches Jim eye the biobed readouts, no doubt checking each against his memory of a healthy Vulcan normal. 

Jim then stares down at Spock on the bed, hands locked in a deathgrip around the sides as he rakes over Spock’s face with his eyes. It’s almost as if Jim suspects that Spock might be an imposter, and if he can only find the single wrinkle out of place he will be able to prove it. 

A smile tugs at Jim’s mouth and his shoulders sag with relief, but he doesn’t relax. The captain is still in control: Jim is not all here, not yet. 

He glances up. Bones feels his gut freeze, nausea roiling in his stomach as Jim meets his eyes. “Bones.”

He bites his lip, shifts on his feet. “Captain.”

Jim’s hand has settled on Spock’s shoulder (an unconscious decision, no doubt), but his blue eyes are piercing. “Bones, what happened?”

Of all the questions he didn’t want to answer. Bones straightens, subconsciously, shoulders squaring. Report. Jim is not your friend right now - your incompetence and malpractice almost killed his officer. 

“Spock was being poisoned by some of the alien juices that got into his bloodstream. I gave him several shots to counter the poison, but that specific combination turned out to be deadly for him. I’d never tested them together on his physiology before - they’re safe for humans but… not him.”

Xenophobia, perhaps? The old southern doctor, so used to treating humans that he forgot how to take care of an alien? Bones remembered the Andorian with the broken antenna, remembered that years-old uncomfortable itch that came from treating non-humans… he thought of Spock’s green blood flowing too slow in his veins and felt sick. 

“Well, you had to treat him, didn’t you Bones? You couldn’t have known.”

Couldn’t have known, couldn’t have tested Spock for every possible combination, but… “The all-purpose antidote. It’s weaker, but it would have been enough to save his life. He was strong, Jim, at first. I didn’t need the stronger dose for the surgery.”

Jim’s hand tightens on Spock’s shoulder, and he straightens, pulling away. His eyes are steely, his jaw set. The captain is ready to fight. “But you couldn’t have known! There could have been unknown complications during the surgery. It’s an alien poison, like you said - there could have been unexpected side-effects! If you used the all-purpose antidote, Spock might not have been strong enough to handle them!”

“The unexpected side-effects came from the antidote, Jim!” He’s raising his voice now, almost yelling, which he tries not to do in sickbay when he has unconscious patients, but the shock is wearing off now, leaving dread and horror and a soul-deep anger at himself. 

“But you couldn’t have known that!” Jim’s finger is out now, jabbing in Bones’ direction as Jim’s face flushes. “You took a chance that the medicine would work - they worked individually, they worked together on humans, it was a reasonable chance - and you took that chance that it was safer to try the medicine than to use a weaker antidote that would leave Spock vulnerable to potential side effects from the poison. It didn’t work out… but you couldn’t have known.”

Bones feels adrift in the way he often does when Spock makes a particularly annoying point in one of their arguments. It’s the feeling he has when he knows he’s right, knows it with every fiber of his being, but he can’t think of a logical reason, a good argument to support his position. The feeling where the very essence of his being is screaming that he is correct, that this is the way things are … but he can’t reach out and make people see .

Jim doesn’t understand.

“I’m a doctor, Jim. I’m supposed to save lives, not take them! Do. No. Harm. That was the oath I took and…” he sweeps a hand over Spock’s unconscious form. 

“It was my recklessness that endangered Spock’s life. My fault.”

Jim seems almost to deflate, eyes melting, softening. He’s Jim Kirk now, and he raises a hand to place on Leonard’s shoulder, but Bones flinches away. Do no harm. What a joke.

Chapter Text

Bones sits in his quarters, staring at Spock’s latest physical. He was out of the medbay, finally, and everything pointed to a full recovery. The negotiations had wrapped up nicely, with another planet joining the Federation. Everything had worked out. 

No thanks to him. 

Bones hadn’t gotten more than a couple hours of sleep at a time since his miscalculation with Spock’s surgery. Jim remained insistent that nothing was Bones’ fault, and Christine had agreed with him. 

Leonard couldn’t see it that way. 

Do no harm. He had one job, one rule above all else… he looked back on his loosened mania for understanding Spock with disdain. What kind of doctor would accept not understanding their patient? He had given up, relaxed when he should have studied, and Spock had almost paid with his life. 

Leonard buried his face in his hands, squeezing his eyes shut despite the dimness of the room. Spock’s results lay spread out before him, each innocuous detail sinister with hidden potential. 

Who was he kidding? He was just an old country doctor, better suited to set broken arms and cure colds than traipse around the galaxy treating aliens. Why did he ever think he could do this? Was it just to run away? Was his cowardice the reason the Enterprise didn’t have some xenospecialist on board, someone who could’ve understood, treated Spock? 

The pressure of the Enterprise seemed to bear down on him, then. 430 lives, each relying on his expertise and knowledge. Every single one of them had been in his medbay at one time or another. 430 people, each one trusting, believing that Dr McCoy could save them, that there was something he could do if it all went wrong. 

If only they knew. 

Bones tossed a longing glance at the Romulan ale stashed away in his quarters, before yanking his gaze back down to his work. He needed to be working, not trying to drown his pain. And honestly, how pathetic was it that he was the failure, that he had made the mistake that had nearly cost Spock his life, and that he had the gall to sit here and feel sorry for himself, as if McCoy was the one who had been so terribly wronged. 

It was just like Josephine had always said - he was always looking for ways to play the victim, even when everything was his own fault.

The door to his quarters chimed, and Bones picked his head up to eyeball the door. Jim, perhaps? Here to give him a lecture on accepting his limitations? “Come in,” he called, and nearly groaned when the Hobgoblin himself strolled in as if he owned the place. 

“Mr Spock, what can I do for you today?”

Spock remained standing, staring down at McCoy’s lounging form with his head tilted, like a curious cat. His skin looked good, McCoy noted, almost hysterically. You could hardly tell he’d been blown up.

“Doctor,” Spock started, his eyes drawn in veiled concern. He should be careful, Bones mused, or he was going to get constipated from expressing so much emotion. “Doctor, I thought I should thank you for your contributions to my recovery.”

He laughed at that, actually laughed, short and sharp and bitter and Spock drew back as though trying to categorize this illogical emotional reaction.

“Are you thanking me for botching your medication, or for throwing such a huge pity party over it that T’Nira could telepathically feel my caterwallin’ from planetside?”

“I am thanking you for your work in preventing my immediate death. I had sustained several potentially lethal injuries, and only a skilled surgeon could have prevented a fatal reaction.”

“A ‘fatal reaction’ - yeah, like what you would’ve had after I poisoned you.”

Spock sighs, a brief huff of air through his nose, and a disconnected part of Leonard cheers at drawing so many emotions out of the man. 

“Leonard…” ooh, full name. He’s in trouble now. “You could not have been expected to predict the negative consequences of your chosen plan of treatment. Furthermore, if you had attempted to utilize the all-purpose anti-toxin and I had experienced complications during surgery, I would most assuredly have died.”

“There weren’t complications,” McCoy scowled, unwilling to take the out. “Except from what I gave you.”

“But you had to take the chance that there could have been.”

“If I’d just done my research beforehand -”

“Doctor, you could hardly have researched my biology further without opening a facility and devoting yourself to documenting the nuances of my genetics. You do, in fact, have responsibilities other than the complete documentation of my genetic abnormalities.”

“A doctor is supposed to care for their patient.” McCoy drops his gaze, because that really is the crux of it, whether Spock understands it or not. “I’m just an old country doctor. What do I know about treating aliens and hybrids…” McCoy feels his vision slide out of focus as green blood shimmers on his fingers. “...I shoulda stayed in Georgia…” 

“That would have been highly regrettable, doctor,” Spock intones, and McCoy swears he hears concern (and panic?) in that measured voice. It’s just his imagination, more likely than not - he projects onto Spock, he knows, but surely the green blooded hobgoblin would be panicking in the face of McCoy’s illogical human emotion. This situation couldn’t have been in any of the textbooks they fed him on Vulcan. 

“Yeah? Well maybe if I had, the CMO might’ve been someone with a specialty in xeno-biology! Maybe someone else would’ve been prepared to…” McCoy waves a hand in Spock’s general direction. “... deal with you.”

Spock’s head tilts, and even McCoy can’t guess at the emotions playing behind those guarded eyes. “...Doctor. I would remind you, first of all, that you are a specialist in xeno-biology-”

“It’s not the same , I know so much more about humans, there should be someone better -”

“And secondly, I find it deeply unlikely that your replacement would be any better suited to care for me than you are. My biology is unique, as you well know. Only the biologists who created and studied me growing up would have the qualifications you seem to require. And as far as the rest of Starfleet…” 

Spock pauses, and McCoy straightens, sure that something important is happening, if he can only understand it. “In a ship of 430 crewmen, I am the only non-human aboard. You have dedicated yourself to chronicling my biology with astounding tenacity, despite the fact that no one expected this from you, aside from yourself. No one would have blamed you for keeping your focus on humanity on a ship with 429 human shipmates. But even for the sake of one, you are determined to learn an entire field of biology, simply to keep me alive.”

Spock’s long-legged strides bring him beside McCoy where he settles into a chair beside Bones. He knows that his eyes are bugging wide, and his heartbeat feels too hard in his chest. The back of his mind is buzzing with protests - surely any doctor would do their best to help their patient, he isn’t special - and Spock is complimenting him? McCoy tries to pinch himself surreptitiously, as Spock’s eyes lock onto his own. 

“Those of your profession are required to take an oath to ensure that they use their skills only for the benefit of others, but I do not believe you ever required this oath. It is integral to you, as intrinsic as breathing. You could no more betray that oath than you could your own soul. Doctor - it is illogical for you to castigate yourself over mistakes for which you hold no responsibility when there is no other I would have as Chief Medical Officer of the Enterprise.”

Oh. Illogical , was it? To think, they’d almost had a conversation without that word rearing its’ ugly head. Bones blinks, once, twice, tries to decide if he really heard what he thought he did. Spock stood up, brushing invisible dust off his uniform. 

“Really, Doctor, you must reduce this drinking habit of yours. You are prone to hallucinate things which never happened.”

Up went that eyebrow, and Spock strolled out of McCoy’s room, pleased as the cat that swallowed the canary. Message received, Spock, Bones snorted, leaning back. This conversation never happened. 

Staring at his ceiling, Bones felt a smile tug at the corner of his mouth. Who knew the hobgoblin had it in him? 

He turns Spock’s words over in his head, examining them. It feels wrong, almost sacrilegious, to just accept that he may not understand everything about his patient - that even a lifetime of study wouldn’t be enough to uncover all Spock’s innate secrets. And yet, the thought of Spock under the care of some other doctor - someone who didn’t have the time or energy to devote to understanding a single man when he had so many other responsibilities - it repels McCoy like a physical shove.

He’s not perfect, but he won’t be handing over his ship and his hobgoblin to anyone else. He’s a doctor. And Dr McCoy looks after his patients.