Notes: I'd apologise for falling into the '5 and 1' traps, but I've always sort of liked them. So here you have it: five times McCoy knew more about Vulcans than Jim, and one time Jim had it covered.

Disclaimer: I do not own Star Trek and I make no profit from this work.

Xenobiology

One:

"Bones."

It wasn't like Jim to enter Sickbay - or McCoy's office - quietly, so McCoy jumped when he suddenly heard his voice. But his snide remark was cut off at the serious look on Jim's face, and McCoy ran a mental check on who was on duty in Sickbay right now.

"What's wrong?" he asked flatly.

"It's not me," Jim said, worrying at his lower lip with his teeth. "It's Spock."

Oh sweet Jesus. McCoy never liked hearing that phrase. Sometimes, he questioned the judgement of the chain of command. While he was okay with Vulcan biology, and Dr. M'Benga was even better, neither of them were on a par with an actual doctor for Vulcans. He was already kind of praying nothing went seriously off the charts in Spock's systems.

"Right," he sighed through his teeth. "Well, what's wrong with him?"

"He's not sleeping," Jim said, sitting down in the waiting chair. He was still gnawing on that lip. "It's been like, a week, since I saw him sleeping. And probably five days before that. And..."

"Slow down," McCoy said. "What's he doing instead of sleeping?"

Jim shrugged. "Well. He usually meditates, but I wake up when that chime announcing shift change goes off - the 0400 one - and whenever I do, he's not in our quarters any more. I did ask, but he just said he was working in the labs and not to worry about it, but..."

McCoy interrupted again. "And he's meditating every night?"

"Yeah."

"Then he's not lying to you," McCoy shrugged and leaned back in his chair. "Vulcans really don't need as much sleep as us, Jim. The meditation lets most of the Vulcan brain rest and recycle without the need for actual sleep. And they don't have REM sleep in the first place - their brains don't need to go over everything the way ours do. As long as he's regularly meditating, sleeping one or two night a week is fine."

Jim deflated slightly. "Really?"

McCoy nodded.

Finally, that gnawed lower lip got released. "You're sure?"

"Yes, Jim. Jesus. I'm a doctor, not a con artist. Now get out of my office. There's nothing wrong with your First Officer - and next time, try actually looking for signs of tiredness. Even Vulcans show 'em."

"Not that one," Jim sniped, and McCoy had to concede that he probably had a point.

After all, tiredness would be illogical, right?

Two:

"Spock, sit down."

If Spock were human, he would have jumped. As it was, Jim just got an eyebrow, and was then ignored. McCoy just shook his head and carried on waving his tricorder in seemingly erratic patterns.

Jim was confused. They'd returned from an away mission that would have been remarkably easy, if not for the fact that nobody knew that the foliage secreted toxins that could be absorbed through the human skin.

Well, they knew that rather quickly after Ensign Tanasaki and Lieutenant Moretti had both collapsed in very short succession, collecting samples for the science labs from a particularly odd-coloured flowering bush.

(It had fluorescent green flowers. Jim had seen duller greens at neon parties at the academy. He couldn't blame the eggheads for wanting to know why they were that colour.)

The result? Everybody in Sickbay for checkups.

And Spock, instead of sitting on a biobed like everyone else, was standing ramrod straight beside one. And McCoy wasn't even bothering to do anything about it.

"Spock," Jim called again, earning himself a tut from the nurse taking his blood sample. "Sit down. The biobed isn't going to bite."

"No, but it'll scream at us, and I'm sure you don't want Nurse Reynolds to jump while she's got a needle in your arm, Jim," McCoy pointed out. Nurse Reynolds chuckled and removed the aforementioned instrument.

"Feel free," she said. "Stay here," she added to Jim sternly, before scurrying off.

"Nurse Chapel's training them all to be fierce where you're concerned, Jim," McCoy said, and chuckled. "Spock, I'm not getting anything abnormal on here. I'm letting you off, but if you feel any odd symptoms whatsoever, I want you back here immediately."

"Understood, Doctor."

"Why would the biobed scream?" Jim persisted.

"Tenacious, aren't you?" McCoy muttered.

"The biobed is adjusted to human parameters, Captain."

"Jim," Jim corrected, pulling a face. "Jeez, Spock, you'd think by now you'd be calling me by my first name. And anyway, why scream? It only does that if there's a major problem."

Spock was giving him the 'not on duty' look, so McCoy answered him.

"Because in human terms, Spock has a major problem," he said. "That heart of his is pushing that green ice-water around his veins at a rate that would be a major heart attack in humans."

Jim's eyes widened.

"Vulcans have a resting heart rate of around two hundred and forty beats a minute, Captain," Spock informed him. "Rather more accelerated than the human heart."

"Spock's, right now," McCoy wiggled the tricorder again, "is two hundred and forty seven. The biobed would freak. Just a machine, you see, can't tell the difference between a human and a hobgoblin unless I tell it otherwise."

He smirked then, and Spock shot him a dirty look. Well, as far as Vulcan dirty looks look anything different from their normal bland expressions.

"Go on, both of you, back to minding the store," McCoy said. "Otherwise, Jim, Nurse Reynolds'll have your shirt off and be listening to your chest. She's got a thing for you."

Spock looked distinctly displeased at this news, so Jim hurriedly steered him towards the door and tossed a scowl over his shoulder at McCoy.

Didn't stop McCoy from overhearing: "So, if I put my ear to your heart, would it sound like humming? Or purring?"

Hell, let Spock handle that one.

Three:

The Sickbay doors - like any other door on the ship - did not react to chaos, panic or any other kind of disordered, disastrous situation in the slightest. So they hissed open quite peacefully, as they always did.

And then the noise hit.

"Bones!" Jim's scream was just that - a scream. A noise of fear and anguish and helplessness, and McCoy was out of his office and running before he even felt the sharp stab in his chest that came from hearing his best friend make that kind of noise.

"Get him on a biobed!" he yelled, the moment he took in the situation.

Jim and the ensign who took Gamma Shift in the transporter room - Merakoto? - were supporting Spock between them, who was either approaching unconsciousness, or had already hit it. All three of them were covered in blood - bright green blood - and McCoy started hollering to Chapel.

"Get Dr. M'Benga, now!"

She bolted from Sickbay. The other doctor was off-duty, and as they got Spock flat out on one of the biobeds, McCoy uncharitably thought that he'd picked a hell of a time to switch shifts.

"What the hell happened, Jim?" McCoy barked, adjusting the biobed to Spock's parameters. It whimpered anyway - not screaming, not yet, but it wouldn't be long.

"Negotiations turned nasty," Jim choked. He was white-faced and shaking, leaning over the biobed to gingerly stroke Spock's hair. "Projectile weapon, like an old Earth gun. We didn't...we didn't realise he was hit until we were beamed up. It was...it was so fast, and then he just..."

He broke off, running his fingers through Spock's hair, and the pain on his face tore again at McCoy's chest.

"Is the projectile still in him?"

"I don't know," Jim said faintly.

The wound was small, located between the second and third ribs, and McCoy suspected a grazed lung. But there was an also an exit wound in his side, equally small. Minimal damage, likely, despite the havoc that any projectile weapon caused to anyone's systems. Vulcan or not, Spock was going to suffer for this one.

Very strong projectiles, though, not to break up inside. Despite himself, McCoy was curious.

"Bones?" Jim whispered, when the biobed readouts started to change. "What's happening?"

Spock's heartrate and respiration rates were both plummeting, and his brain activity was shutting down, section by section. Jim knew enough about the beds to notice, and any remaining colour in his face left it promptly.

"No!" he hissed, raggedly, and he pressed his lips to Spock's forehead. "No, don't! Don't! Don't you dare leave me, don't you dare..."

"Jim!" McCoy intervened hastily, drawing him away from the Vulcan. "Don't interfere. Don't distract him, leave him be..."

"No!" that denial was another scream, angry and shrill, and McCoy felt more than saw the bloodied ensign draw away in surprise. "No, I won't let him...!"

"He's not dying, Jim!" McCoy barked, shaking the Captain roughly. "He's not dying! He's entering a healing trance - see that needle? How it's gone up? Those are his dopamine levels. He's going into a trance to try and fix the damage."

Jim was still shaking like a leaf in his arms, and hadn't taken his eyes off the prone Vulcan for a moment, but his voice was more stable when he asked: "He's going...he'll be...?"

"Dr. M'Benga and I will close the wounds up and pump him full of antibiotics. He might need a transfusion, but the trances speed up blood production, so he might not. He's not going to be up and about in the morning like he usually is, but I promise you, Jim, he'll be fine."

It took another couple of minutes - during which McCoy returned to the patient in question - before Jim managed to pull himself together. When he did, he crossed to the communications console, informed Sulu that he had the conn, and returned to the biobed.

"Jim, you can't come into surgery," McCoy said sternly.

"I know," Jim said, settling by the bed anyway. "But M'Benga's not here yet, and you'll need to prepare. So I'll stay until then."

Four:

"Hey," Jim appeared in the doorway to his office like a spectre the moment Alpha shift was over. "How's it going?"

What he really meant - and McCoy knew it - was 'how's Spock doing?', but (for whatever reason) he didn't want to be so forward as to actually ask.

"He's fine," McCoy said flatly. "He'll probably come out of the trance tomorrow. And then at least a week off-duty before I'll even think about allowing him back on the bridge. He took a nasty hit, Jim, and he still hasn't quite replaced all the ice-water."

"Why do you call it that?" Jim asked as he made a beeline for Spock's bed. Deep in the healing trance now, it didn't matter whether Jim touched him or not, so he curled a hand around one pale wrist and squeezed lightly.

"Call what?" McCoy asked, checking the readouts before leaning a hip on the end of the bed.

"His blood. Why do you call it ice-water. I mean, I get the green thing, but..."

"It's colder than our blood," McCoy gave him a funny look. "Seriously, Jim. You're sleeping with him and you hadn't noticed the lower body temperature?"

Jim flushed. "I did! I just thought...you know, Vulcan's...Vulcan was...hotter than the ship. I thought he was chilly."

"Probably is," McCoy agreed. "Keeps his damn quarters enough like a sauna. But no, he really is colder than humans."

Jim stroked his fingers over the captured wrist. "How much colder?"

"Seven degrees Fahrenheit, usually. Vulcans can tolerate a larger range of body temperatures than we can, but he'd probably die if you sustained him at ninety-eight degrees like us."

Jim shivered and scowled. "Don't say shit like that, Bones, seriously."

"Sorry," McCoy rolled his eyes. "I'm still kind of surprised you didn't figure that out. I mean, he's colder than you. Of course his blood's going to be colder than yours."

"Yeah, well," Jim said waspishly, "until Tuesday, he hadn't poured that blood all over me, had he?"

McCoy didn't say anything to that.

Five:

He found Jim in the mess hall.

"I have a bone to pick with you," he snapped, sitting down unceremoniously in front of him and pushing the tray to one side.

"Hey!" Jim protested.

"Seriously," McCoy said. "I just had Spock in for his yearly physical."

"So?" Jim almost smirked. "Trust me, everything's ticking. Shore leave was proof enough."

"Uh-huh," McCoy drawled. "I would never normally ask this, but what the hell happened on your shore leave?"

Jim was beginning to look a little concerned now. Maybe the stupid kid had finally twigged that McCoy wasn't dicking around here.

"Umm...sex," he said finally, and McCoy grimaced. "Lots and lots of sex. A couple of those mind meld things."

"A couple?"

"Fine, a lot. What's your point, Bones?" Jim frowned. "We have sex all the time. Emotionally repressed or not, believe me, Vulcans enjoy it too."

"They reproduce, don't they?" McCoy griped. "Jim, since the loss of Vulcan, we know a lot more about their biology, because they can't handle it alone any more. There aren't enough healers left. And I've been keeping an eye on Spock's medical results in case this happened!"

"'This' being...?" Jim prompted.

McCoy gritted his teeth and lowered his voice. "The Vulcan mating cycle. Pon Farr, Jim. And from the results I got just now, Spock's either just been through it, or the shit's about to hit the fan in the next week."

"Err..."

Jim suddenly looked very, very awkward, and had a sudden desire to examine the tabletop in all its plastic detail.

"Oh Jesus, Jim..."

"That...might explain a few things," Jim said, then hastily added: "What? It's not like he forced me into it! I just thought, you know, he was...horny."

"Not everyone is you, Jim," McCoy growled. "Horny, for most people, doesn't involve massive hormonal changes, enough adrenalin to kick-start a Klingon war vessel, or sex marathons!"

Jim squirmed. "Well, um. It did this time?"

"No it didn't, Jim," McCoy groaned. "You just better hope you haven't caused a bloody incident with this. I have no idea how Vulcans handle it - they could have a list of protocols as long as your list of sex partners, and you just threw a wrench in their logical works."

Jim frowned. "I'm...I'm sure Spock would've...said something. He...said a fair few things. But...yeah. I don't speak Vulcan, so..."

McCoy groaned again. "Look," he said, standing up. "I'm going to check there isn't going to be some medical backlash from mating with a non-Vulcan - or a man, for that matter. You'd better check that he's alright. God knows with their telepathy shit, you've probably gone and married him or something!"

Jim went magenta.

One

Spock flinched.

He actually flinched, which was enough to have McCoy sitting up and paying attention. But Jim was even faster, out of his seat and crouching beside Spock's in a moment.

"Has it happened?" he murmured, in a very low voice, and when Spock only nodded, he helped him up out of the chair and was taking him swiftly from the mess hall without a further word.

McCoy caught up to him that afternoon, at the end of Alpha shift. During which, Spock had been conspicuously absent from the bridge.

"What's going on with that Vulcan boyfriend of yours?" he demanded once he and Jim found themselves alone in the turbolift.

"Huh? Oh. His...great-aunt or grandmother or something. I forget. Whatever; a relative's been really ill lately. She just died," Jim shrugged. "After Vulcan was lost, he hasn't got that many more relatives, so I guess he...felt it more."

McCoy blinked. "Felt it more?"

Jim frowned and said, "Um, yeah? The family bond getting snapped? They don't like that."

McCoy did know that Vulcans shared bonds with their relatives; what he didn't know was that they could cause physical pain when broken, the same as mating bonds did.

"Well, after...the whole Nero thing...he hasn't got as many bonds left," Jim said. "So he felt it more. And he always liked her - not that he admits it, but he does."

"Ah," McCoy said. "Is he alright?"

"Yeah," Jim said. "I gave him the rest of shift off. He should be asleep in our quarters, but he's probably not."

"Well, send him my way if he needs anything for it," McCoy said, as the lift doors opened and deposited Jim outside his quarters.

"Don't worry, Bones, I got this covered."

Jim entered his quarters quietly. The lights were dimmed, and to his surprise, Spock really was in their bed and - seemingly - asleep. He changed quietly, locked the doors and checked for messages before sitting on the edge of the bed and carding his fingers through that short, dark hair.

"Hey," he murmured, when the Vulcan finally opened his eyes and looked at him. As always, when they were alone, his eyes were more open and easier to read. "How you feeling? Really. None of this 'adequate' shit."

A ghost of a smile tugged at the corners of Spock's lips, before he said, "The pain had...diminished somewhat."

"But not entirely?"

"No."

Jim hummed sympathetically, kissing his forehead and lingering for a moment before asking, "Do you need anything?"

Spock caught his hand and stroked their fingers together. "Only you."

Jim smiled - not his hundred-volt grin, but a softer smile that he rarely allowed out in public. One that Spock, by contrast, had seen a thousand times. "Yeah, okay. I know that much about Vulcans."

"Not Vulcans," Spock corrected as Jim squirmed under the covers with him.

"You're right," Jim agreed, stroking lightly over the migraine tension still hovering in Spock's temples. "Just the half-human ones."

"Indeed."