A/N: Inspired by a prompt on the trek kinkmeme (trekkink) on livejournal. Apologies it takes a bit to get to the actual purring - Jim and Spock distracted me with cute before we got there :)
"You go get some rest too, okay, Jim?"
Sickbay's lights were turned low for the night and the biobeds chirped softly every few minutes. Jim saluted without looking up from the padd he was working on. "Got it, Bones."
Bones leaned against his office door, only his eyes betraying the twelve hours he'd just spent patching up the away team. His mouth was set in a tense line but he looked with weary affection at the pair. They shared a biobed; Jim sprawled out and propped up, legs crossed, working on a glowing padd. At his side, Spock had started off rigid but now had his head on Jim's shoulder, fast asleep.
Spock was only there because he'd got his hand caught in the grip of an alien machine and had to have it osteogenically stimulated overnight. Technically he'd probably be fine in his own quarters but the beds kept track of their patients' vitals and sent alerts when something was off, so he thought it best. Then of course Jim came in and didn't leave.
Jim looked up. "So am I." A smile played at his lips, daring Bones to challenge him. He seemed to settle in more, just to make his point. Bones sighed.
"When I say rest I mean sleep, you hear?"
"Yeah, yeah." Jim turned back to his padd, and if Bones looked hard enough he could see the beginnings of shadows under the captain's eyes.
"If you really want to stay here-" Bones started. Jim looked up with a Really, Bones? quirk of his lips. "Then just get to a biobed or something."
"Bones, I am in a biobed. And we'll be fine, don't worry."
Bones didn't even have the energy to roll his eyes. He sighed good-naturedly and turned off his office light, lingering a moment longer just before the exit. Another warning was on the tip of his tongue, but he stopped. Even if Jim got no sleep tonight - which was a definite possibility, considering - these moments were good for him. Good for Spock, too. But, then again, Bones thought while trying not to think about it, they were probably set on the whole being together front. Right. Bones slipped out before his imagination had time to catch up to his sleep-deprived mind.
The doors whooshed shut behind him.
A minute after Bones was gone, Jim glanced up to the exit doors and made a quick sweep of the bay. There were a few other patients but all were asleep. He turned off his padd and pushed it under the pillow, shifting slightly and bringing Spock's wounded hand out of the space between them. Jim hoped the light tingling between their fingers was a sign that all was going well. He swallowed and rubbed Spock's knuckles, the pads of his fingers brushing Spock's cooler ones.
Spock was in a light trance now, focusing his energy on fixing the delicate bones in his hand, repairing the even more delicate nerve endings in his fingers and palm. He'd started to slip into unconsciousness soon after Bones had finished wrapping the reflective healing bandages - working synchronously with the stimulator - around his wrist.
Jim had nearly had a heart attack - several heart attacks - when he'd heard Spock's muffled groan on the alien ship. Normally he was so careful but something had unhinged while he was trying to get at sensitive wiring, sending a plate slamming down on his wrist. Thankfully it didn't crush his hand - it was just gravity releasing a heavy metal object and Vulcan bones were stronger than humans' - but Jim had decided immediately that Spock had to be beamed out. Spock held his hand protectively to his chest as the only indication he'd been hurt, eyes still flickering impatiently. He protested his removal from the ship even as Sulu and Chekov began to repair the damaged system in his stead. Jim had kept him back with a firm look and careful words, getting Scotty to bring him back. It had hurt him to beam Spock back alone, but Bones would take care of him and they had a job to do.
When he'd gotten back he'd immediately wanted to link their fingers together but had carefully avoided doing so because he'd been worried the contact would do more harm than good, drain Spock's energy or something. Spock had concealed it well but Jim soon realized he was confused about why Jim was avoiding touching him at all. Jim quickly backtracked.
"Can we?" he'd asked. "I don't want this to hurt you or anything..."
Spock's eyes softened and he lightly touched the back of Jim's wrist. Jim grinned and turning his hand over so their fingers brushed. A trickle of somewhat excited thoughts seeped into Jim's mind. He hummed.
"No, it won't hurt," Spock said. "The physical link had been know to speed the process..." He slowed his breathing and Jim felt the slow trickle strengthen. Jim had done this many times before but it always left him with a sense of wonder. He hadn't dared unlink their fingers after that.
Jim marveled again at their joined fingers. Though the mental connection between them was invisible, he felt it, the ebbs and flows, the hints of thought and feeling from Spock's mind, the knowledge that the Vulcan was picking up on his. Spock was probably getting a lot more from his mind than he was from Spock's though, Jim thought with a small smile. Just then he detected a hint of negation through the link.
Oh, you're not reading my mind, then? he asked playfully back in his head.
Not directly... not if you do not wish it, Spock replied promptly, if a little sleepily, and Jim could more like feel the words than hear them.
...what if I wanted you to 'intrude'?
...then I could, if you wished...
But Jim didn't want them to go into an all-out mind meld when Spock was recovering, so he didn't reply. Spock shifted and Jim continued to rub his hand, gently and thoughtfully.
Then, a sensation prickled close to his shoulder, a soft thrumming. Jim stilled and held his breath. What was that? The biobed had to be malfunctioning. Maybe it'd stop if-
It did stop. Jim glanced to Spock. His eyebrows were drawn and his hands twitched slightly. Jim started to rub again, and the sound returned. Spock shifted further and the noise intensified. Jim's jaw dropped and he bit his lip to keep from laughing in amazement.
Spock was purring. Jim grinned. Of all the things he didn't know about Vulcans, he never thought purring would be on the list. Were they secretly related to cats? That would explain the inner eyelid he supposed... Jim carefully maneuvered his arm around Spock, then, pulling him closer and settling him in. Spock curled into his chest, legs drawing closer. The vibrating coming from Spock's throat dulled when he moved but continued a moment later.
Jim continued rubbing Spock's hand, sure that was what was causing it.
Then it stopped again and Spock snuffed and yawned softly. He blinked and glanced down to their hands, fingers joined. He rubbed his own thumb along Jim's knuckles. Jim squeezed back. He hesitated for a moment before whispering softly:
"Yes, Captain?" Spock murmured drowsily. Jim smiled.
"You were purring." He leaned closer and said this gently against Spock's hair, breathing in the Vulcan's musky, spicy scent. He kissed Spock's head and hummed.
Spock's eyebrows drew together in confusion and he flushed green. "I apologize-"
"Whoa, Spock, don't apologize, please. I liked it."
Spock looked up at him cautiously and Jim kissed him again, shifting their fingers to send positive feelings down the line. "I liked it a lot..."
"We don't do it often," Spock said carefully. "It evolved in our species as a way to aid the healing trance - the vibrations help correct the bone density we might loose from resting for long periods of time during the trance, and it also helps increase bone density if, you had, perhaps, suffered a fractured wrist..." Spock quirked his lips and Jim caught the connection a moment later. He laughed quietly and pulled Spock tighter. Spock closed his eyes and their link hummed.
"So you guys aren't descended from tigers or anything are you?"
"Not that I am aware..."
"I'm kidding, I'm kidding - though if you were I'd be totally cool with that..."
Spock didn't reply, and Jim noticed his breathing was deeper, slower. Jim himself settled down more and after several minutes his eyelids drifted closed.
Jim roused without fully waking. "Yeah?"
"It can also be induced by pleasure."