If someone were to ask Doctor Leonard Horatio McCoy for his views on Jim Kirk, he would tell them that the man was a thorn in his proverbial backside. He would say that it was easier to get a cat under a showerhead than Kirk under a hypospray, and that being the man's Doctor had taken more years off his life than he had lost hairs on his head. He would tell them that Jim was the most insufferable, smart-mouthed and brilliant Captain in known space, and probably far beyond. He would tell them that he trusted Jim Kirk with his life.

What he would not tell them is that he would trust Jim with far more than just his life. He would trust Jim with his daughter's life, the one thing in the universe which he valued above all else. He would trust Jim with his secrets, and his bitter disappointments, and the few ragged dreams that had survived his thirty-odd years. He would trust Jim to soothe him on those nights when old memories and regrets rose up like so much black smoke and forced him to retreat so far into the bottle that he was unsure of everything but his name and the blue-eyed kid at his side. He would trust Jim to kick his ass in the mornings after, and taunt him out of apathy and self-pity.

He would not tell them that he viewed Jim as a best friend and a brother, and that what he wished for more than anything was to see the bright-eyed, restless and world-weary young man content.

It was with a kind of resigned horror that McCoy realised Jim Kirk was still on-planet after the beam out. The first thing he did was curse himself for taking his eyes of his touble-prone best friend for even a second. The second thing was to palm the snivelling Mathers off to a concerned Christine Chapel and co.

Spock was at Scotty's side seemingly before the beam up was even complete, talking to Jim through his communicator and eyeing the quailing Chief Engineer with an unforgiving eye. McCoy joined him in time to hear Jim's terse, "Standby" from the other end of the line, and then nothing.

"Spock? What the hell is going on? Why is Jim still down there?"

Spock did not answer, turning instead to the Chief engineer. Scotty held up his hands defensively.

"Dinnae look a' me, Sir, ye'd have a better idea than I would. All I know is wha' he told me: no' tae beam him up when the time came."

Spock's fingers clenched in an uncharacteristic show of frustration.

"He has ordered that we make no further attempts to beam him out," affirmed Spock stiffly.

McCoy gaped. "He…what? But it's a death-trap down there! Those people are sick, and dangerous. Bugger whatever Jim's thinking, we need to get him out of there."

"We cannot go against the Captain's explicit orders, Doctor. He would not take these actions without a reason."

"What reason?" yelled McCoy, his fear – as always – finding refuge in anger.

Spock's eyes flashed, and McCoy could see, in that instant, that he knew – or at least thought he did. He could also see, from the paling around the Vulcan's lips and the tightening of his jaw, that he probably would not like the answer.

"I am sure the Captain will tell us in due course," responded Spock tightly. "Until that time, both Uhura and I will attempt to hail him periodically. Doctor?"

McCoy, who had been backsliding inward in his worry, jerked his head up to meet the Vulcan's gaze.

"If I can find a way to bring diseased tissue and samples on board without risking the spread of infection, do you have the facilities to begin working on a possible treatment for those on the surface?"

McCoy was somewhat thrown off balance by the seemingly abrupt change in the Vulcan's focus, but he nodded distractedly. "Yes, yes, of course…I can work on it…but what about Jim?"

"The Captain would want us to continue as we always have in his absence, and assist those in need. Would you not agree, Doctor?"

McCoy nodded, first absently, then with growing conviction.

"Alright, Spock. But until you find some way of getting those samples aboard, you're not getting rid of me. I will be there when you make contact with Jim, to see what damn-fool situation the idiot's got himself into now."

To McCoy's surprise, Spock made no protest, only nodding briskly and exiting the transporter room at a clipped pace.

And so McCoy was with Spock as he hailed Jim periodically every ten minutes. He stood by as the slight but ever-growing strain in the Vulcan's voice grew with every failure to respond. He was there as Spock vented his worry in the most Vulcan way he possibly could – through emotionless, if abrupt, orders to his science team, and unflinching focus on the solving of his current problem.

He was there to witness the moment in which Jim's choked voice finally responded, and through the haze of his own relief, he saw the almost imperceptible relaxing of the Vulcan's shoulders, and the way his eyes slipped closed for just a moment.

Their relief was short-lived, of course. Jim was alive, but he was compromised and wounded and alone. And so fucking far away that it made McCoy want to scream. He wanted to strangle Jim at his casual dismissal of the fact that he failed to tell any of them about his injury before sending them off planet – of his twisted inference that he was not important enough to worry about leaving behind. He wanted to shake him, and hug him, and call him an idiot for ever thinking such a thing could be okay.

He settled for scolding him, and giving him some medical advice that any half-baked ensign could have come up with.

God, he hated this.

At least Spock's fixation on finding a cure had become clear. Of course, the hobgoblin would no doubt be working on one in any case, but the almost manic focus and barely suppressed energy in the normally placid Vulcan was something that could only be attributed to the threat to Jim.

Sometimes McCoy wondered…

He shook off the thought and exited the science lab determinedly, with a promise from Spock that samples would be sent for analysis as soon as they were available. Jim's personal life and what you should-and-should-not-share-with-best-friends could wait until the idiot was safely on board.

For now, he had a medbay to prep.

XXX

Jim's estimate on the distance to the mountains had been fairly accurate. After just over three hours of walking, and three check-ins to the Enterprise, he was skirting the rough fringe of the slopes.

The second sun was low in the sky when he delved into the fold between two slopes to find a promising looking hollow in the mountain face above him. The entrance to the cave was about twenty feet from where he stood at the base of the valley, and he had to scramble and climb to reach it. It was not the first time he had had cause to be grateful for his skill at rock-climbing, however unsavoury the origins of the habit.

He reached the cave entrance, and flopped – exhausted – onto the cool ledge that jutted out a few feet in front of it. Every muscle in his body ached and he was beginning to fear that it was not just the result of his battering in the river, as he had previously hoped. While his earlier antics might explain the muscle-aches, they could not account for the piercing pain that had set-in just behind his eyes, nor the tight, hot feeling of his skin beneath his clothes. Though it was less than a day old, the wound beneath his rough bandages already felt infected – swollen and throbbing with every beat of his heart.

Jim was sick, and he was neither foolish nor hopeful enough to deny it any longer.

He hauled himself up after a few moments reflection, and dragged his body through the cave entrance. There, he perked up slightly. Sure, it was no Enterprise Captain's quarters – and oh, what he wouldn't do for five minutes in his own bed right about now – but it was dry and oddly cosy, with a flat floor which extended about thirteen feet from the entrance before curving up into shadow. The roof of the cave was high enough that he could stand easily without fear of bumping his head. While the size of the space wouldn't allow for much conservation of heat should the weather change for the worse, in the warm climes it made for a cosy and comfortable base.

Stepping outside, Jim was pleased to see that the angle of the cave relative to the entrance of the valley would make it difficult to see unless you were almost on top of it. The recent storm had also left small catchments of water at intervals all along the slope, meaning that Kirk was unlikely to run out of fresh water any time soon.

Despite the fortuitous positioning of the cave, Jim was interested in taking a few more precautions before he lost the last of his light to the sun's descent behind the peaks. He rolled his shoulders and headed a small way down the slope to where he had seen a few shallowly-rooted bushes on his way up.

It took little effort to yank the bushes from the ground, so Jim was surprised when his exertions left him feeling weak and shaky. On the way back up the slope, dragging the spiky branches behind him, he found himself needing to stop several times in order ease the spinning in his head.

"Fucking fantastic," he muttered bitterly as he finally dropped the bushes at the entrance of the cave, and had to sit abruptly and rest for a moment. He breathed steadily in and out, before rising to collect a few largish stones from his surrounds. Luckily, there was scree scattered just below the cave entrance, so he did not need to go far.

He allowed a few stones to clatter to the floor just inside the cave, and breathed in and out steadily, attempting to gentle the tremors in his hands. His trepidation grew when it made little difference.

He jumped when Spock's voice came through the communicator.

"Enterprise to Captain Kirk."

He fumbled the device from his belt. "Kirk here."

"Captain, it has been 1.125 hours since your last check-in. Are you experiencing any difficulties?"

Jim relaxed with slight twitch of his lips. "Apologies for my tardiness, Commander. I've found a place to rest for the night and was just making a few adjustments before dark falls."

"I trust that your current location is secure."

"As secure as it's going to get, Spock. I'm in a cave about eight clicks South-West of the compound. Seem to be quite a few up in these mountains." He wedged the com unit in his belt as he began dragging the brush he had collected over the entrance of the cave.

"Unoccupied, Captain?"

"Seems that way, Spock, but I am taking precautions."

There was a very un-Spock-like snort from the other end of the line.

"Precautions like stranding yourself, alone, on a toxic planet? Forgive me if I'm a tad sceptical of your danger-gauge, 'Captain'."

There was only one person who could say 'Captain' as if it were a dirty word.

"Bones!" crowed Jim, with a heartfelt grin.

"Still haven't forgiven me for that, huh? You know, it's very unscientific to base your assumptions off a single case. I'm usually the embodiment of responsible behaviour – look before you leap and all that." He almost dropped one of the branches he was positioning as his hands spasmed, and grimaced. "Besides, this planet is in fact remarkably pleasant, when you disregard the diseased and homicidal settlers."

"Who would disregard that?" demanded McCoy, but he sounded more amused than angry.

"Captain," cut in Spock. "Doctor McCoy is present to receive an update on your physical health. Are you experiencing any symptoms at this point?"

"What, my mental health not interesting to you guys?" deflected Jim lightly, unwilling to vocalise his symptoms just yet.

"Hardly," snorted McCoy. "I've know you're a few chickens short of a roost for years now, Jim. It's not really news anymore."

"Careful, Bones, your Georgia is showing. And should I be offended?"

"Captain." Spock sounded almost impatient now, and Jim new his stalling was drawing to a close. "It is of vital importance that we know of any symptoms you might be exhibiting."

Jim made a last ditch effort. "Aw, come on, Spock, aren't you gonna ease a guy into it?"

"Jim," said McCoy quietly, and the blonde man sighed.

"Alright," he acquiesced. "But for the record neither of you have any conception of 'small talk'."

He paused in his activities at the cave entrance, and gathered his thoughts.

"I've got a bit of joint and muscle pain, but I can't be sure of how much of that is due to my body's rough treatment earlier. I'm running a bit warmer than usual as well – skin feels a little hot and uncomfortable."

"How much warmer?" asked McCoy.

"Not sure, Bones. Maybe 100˚?"

He heard Bones take a note somewhere. "Go on."

"Well, slight headache started up 'bout…a half hour back? It's…grown a bit since then."

"Like one of your migraines?" interrupted McCoy, sounding concerned.

"Nah, nothing that bad."

"You sure?"

Jim shook his head fondly. "Yes, Bones, I'm sure."

Spock spoke softly. "I was unaware that you suffered from migraines, Captain."

"Not often, Spock, and far less since Bones spotted them for what they were and prescribed me meds."

Spock was silent again, and McCoy prompted, "Anything else?"

Jim huffed a breath, considering. "M'hands are a bit shaky, overall I'm feeling a bit run down, but again, that could be because of everything that's happened today."

"Jim, I've seen you strangled, jettisoned off a ship, roughed up by ice monsters, and still ready to jump up and tussle with a Romulan death ship. And you're telling me today's activities have got you feeling rough?"

There was a small sound from Spock on the other side of the line, like a cough, which while insignificant from any other person, was fairly noticeable from a Vulcan. Jim winced, and made a note to chat to McCoy about tact.

Out loud, he said, "Alright, you've made your point, Bones. It's not just the consequences of cliff jumping."

A heavy silence fell between the three of them as they all considered the implications of this. It was broken by McCoy clearing his throat and asking gruffly, "That all?"

"Yeah, Bones, that's all," muttered Jim tiredly. "Now how about you guys tell me some good news? How's the location hunt coming, Spock? Know where I am yet?"

"Negative, Captain," said Spock, and Jim could tell that the hint of annoyance in his voice was self-directed. "It would seem that the mountain rock surrounding your location contains an element that is interfering with our signal. Any effort to triangulate your exact position have been so far unsuccessful."

Jim hated how put out the Vulcan sounded about this failure, but he could not help but be slightly relieved that his crew was unable to locate him. While he was confident that they knew it was best to keep all crew-members off-planet until a cure was found, and that it was equally wise not to bring him back aboard before then, he could not help but fear that certain members of his crew might do something foolish – like beam down to assist him – should they be concerned enough for his wellbeing. This way, they did not have that option.

"Don't worry, Spock," he murmured. "You'll figure it out."

"Vulcan's do not-" began Spock, but he was interrupted by McCoy's disbelieving groan.

"Don't even start, you green-blooded hobgoblin, I have no patience for your 'Vulcan's do not X, Y and Z' bullshit today. Get over yourself, would you?"

"That would be impossible, Doctor," responded Spock coolly, "as I am, in fact, myself."

McCoy groaned again, and Jim grinned. He knew Spock understood exactly what McCoy was trying to say, but he wasn't about to ruin the Vulcan's fun.

His hands started to shake again, and he tucked them absently between his knees.

"What else can you guys tell me?" he asked.

McCoy was still grumbling about Vulcans and sticks in never-sunlit places, so Spock was the one to reply.

"We are ready to begin efforts to extract tissue samples from the surface," he declared.

"You're sure it's safe?" Jim halted in the act of shifting into a more comfortable position, alarmed.

"Yes, Captain," said Spock, the gentle familiarity in his tone betraying his sensitivity to Jim's anxiety. "I would not initiate operations otherwise."

Jim huffed a breath, and told himself that the quiver in his fingers as he adjusted branches around the mouth of the cave was relief. He blinked in surprise when his forearm spasmed abruptly, causing him to knock a branch out of position.

Spock continued. "The unmanned units will be successful. Once the samples are safely aboard, we can begin preliminary analysis."

"I should leave you guys alone more often," quipped Jim, shifting uncomfortably as the tremor in his hands seemed to spread up his arms to settle in his chest and shoulders. "You w-work quickly."

"I am sure we are capable of the same efficiency with you present, Captain," responded Spock. "We are accustomed to working around you, after all."

Jim laughed. "Touché, Mr S-Spock. I'll have to up my g-game."

"Jim," came McCoy's voice, sounding concerned, "are you cold? According to surface readings, the temperature should be more than warm enough down there. Is there a problem?"

Jim frowned. The tremors that had been restricted to his hands only moments earlier – and that he had disregarded as no cause for concern – now seemed to be wracking his entire body. Even as McCoy finished speaking, a random muscle spasm in his forearm caused his knuckles to strike the stone wall of the cave hard, and he hissed.

"Jim?" queried McCoy.

"D-dunno, Bones," stuttered Jim, noticing the twitch of muscles in his jaw for the first time. "J-just feeling a b-bit shaky. Muscle sp-asms."

"You didn't mention it was like this earlier." McCoy definitely sounded worried now.

"C-cause it wasn't l-like this earlier, B-bones," huffed Jim, annoyed.

Jim cried out as the pain in his head spiked abruptly, coupled with a full-body spasm that left him trembling with aftershocks.

"Jim?" demanded McCoy. "What's happening? Are you in pain?"

Jim opened his mouth to answer, and buckled as agony ripped through his head again. His legs had started to jerk spastically, and he pulled them up against his body, anchoring them with his trembling arms. A particularly violent jerk knocked his head against the wall behind him, and he groaned.

"B-Bones. Head h-hurts," he managed, curling over to press his throbbing temples to his knees.

"Jim, I need you to focus and answer me, alright? Are the muscle spasms only in certain places, or are they throughout your body."

"Thr-th-thr-." Jim grunted in frustration as his tongue refused to co-operate, and forced out, "Throughout."

"Good, Jim, well done. And the pain in your head, how bad is it on a scale of one to ten?"

Jim whined as the pain in his head spiked again. Unlike last times when it dulled immediately afterwards, this time the agony was sustained, and the mounting pressure was like the waters of a dam building within his skull. His eyes felt compressed, and his ears popped strangely.

"-aptain? Jim?" He became aware of Spock's alarmed voice coming from somewhere to his left, and he wondered absently how long he had been calling.

"S-Spock?" he slurred.

"Yes, Jim. I need you to focus and answer Doctor McCoy's question. How bad is the pain in your head, Jim?"

"H-hurts," hissed Jim, not quite following the line of questioning.

"One to ten, Jimmy, I need a number," came McCoy's tense tones.

Jim forced himself to focus. "Nine," he grunted finally. "B-b-but it's g-getting w-worse."

McCoy swore viciously.

"B-b-bones?" whispered Jim, hurting and afraid.

"S'okay, Jimmy, it's gonna be fine." McCoy spoke in soothing tones, and Jim wanted nothing more than to be able to curl into his closest friend and let him make the pain go away.

Another violent full-body spasm jerked his legs out of the hold his arms had on them. His head and shoulders struck the cool stone wall violently, before the aftershocks had him crumpling on his side in helpless agony. The dig of the com unit into the flesh of his hip was a stark reminder of how alone he was.

The pressure in his head built and he keened in pain.

"B-b-bones?" he begged. "I d-don't f-feel s-s-so g-good."

The strain in McCoy's voice suggested he was close to tears, but his words were calm and soothing. "It's alright, Jimmy, just listen to me, okay? I need you to put your com unit down by the wall, alright? And then I need to move a bit away and lie down where it's flat, okay? Make sure you're away from the walls when you lie down. You got that, Jimmy?"

It was a lot for Jim to take in in his pain-muddled state. Part of him, the part that was entirely overwhelmed, was panicking, because his body was out of control and his head was splitting open and Bones was calling him Jimmy and Bones only ever called him that when Bones was scared. Jim wished he knew what there was to be scared of.

But then he heard Spock's voice, and it grounded him like nothing else could, for although the tone was gentle, it was also firm and utterly controlled. There was not a hint of fear in his words as he said, "Jim. Please. You need to listen to Doctor McCoy."

"K-kay, Spock," mumbled Jim. And he forced himself to move.

It took three attempts to get the communicator unhooked from his belt, and the tremors were growing worse all the time. When it finally came loose, it clattered to the ground near the wall, and Jim had neither the energy, nor focus to move it. Instead, he began to haul his twisting and spasming body towards the centre of the cave floor, McCoy and Spock's encouraging words pushing him forwards.

Several times, the pain in his head grew to unbearable proportions, and he could only cling to the cave floor, keening and shuddering, as his limbs twitched uncontrollably. Once, he was sure he had lost himself completely for a moment, and only the irate tones of Bone's distress roused him from his insensibility.

It didn't take him long to reach his limit, and he curled up on his side, facing the com unit a few feet away. The wrenching full-body spasms were coming almost continuously now, leaving very little time to recover between them, and Jim could only close his eyes and ride them out. The agony in his head was all-consuming. He could not see anymore. It could be because the second sun had finally set, but he couldn't be sure. He wasn't sure of anything outside the pain.

"B-b-bones," he whimpered, beyond pride in his agony.

"I'm here, Jimmy. Can you tell me how you are? Has anything changed?"

The words scattered and were lost amid the pain. Jim was vaguely aware that McCoy wanted something from him, but the splintering of his skull escalated and seemed to twist inwards, driving itself into the heart of his being and stripping away all but the simplest impressions. He struggled to push through.

"D-d-dark. C's-s-see…h-hur's, B-b-bones. Sp-p-"

"Sh, Jim, it's okay, just talk when you're able to, alright? Don't force anything. Spock and I are here."

"D'g-go."

"Jesus, kid," choked McCoy. "We're not going anywhere. Just breath for me, kay? Just breathe."

Jim did, and for a moment, the agony in his head seemed to abate.

He twitched. "B-b-bones, I th-think-"

And then there was only pain, followed by nothing.