Spock refuses to coo. He deigns it too undignified.
Besides, he's pretty sure he isn't required to, because he isn't like the others anyway. He wasn't even born on Iota Geminorum IV. He was born on Iota Geminorum III, the result of a hybrid experiment conducted by mad scientists.
This makes him a member of an extreme minority of tribbles currently residing on the U.S.S. Enterprise. He also regards his compatriots' enthusiastic eating binges with a total logical pessimism, rendering him an army of one.
The other tribbles call him blueface, or worse, rough-furred bastard. He's quite aware but doesn't really care. No point in sugarcoating the truth. Content to stay in his hideout, Spock meditates and awaits the catastrophe that would be the inevitable result of unsustainable lifestyle choices and environmental degradation.
But Jim can always find him. And Jim always does.
Spock doesn't know how Jim does it. Literally hundreds of tribbles are on this deck of the ship alone, a number growing at an alarming rate. Yet no matter what crack or nook he hides in, Jim always shows up, purring happily and bringing food.
"How did you find me?"
Jim rubs him at one end affectionately.
"Roses are red, Spocks are blue."
"I'm the only blue tribble on this ship," Spock points out. "And there will not be any additional blue tribbles which may conceivably cause confusion, since as a hybrid I am incapable of reproduction."
"Right. Right. That's why I've been reproducing extra hard for the both of us!" Jim is practically singing. "Soon we'll have more kids than Janice!"
"Jim," Spock wishes he has the feature referred to as eyebrows by this ship's humanoid occupants, just so he can raise them. "Let me remind you again that we are on the precipice of a catastrophic overpopulation crisis."
"Spock, that's so cold! Don't you love our kids? The last one was even growing blue hair when he ran off! I swear!"
He looks at the golden furball in front of him and sighs internally. Jim grins and inches closer, nudging him gently. Jim's hidden oral crevice starts to press against his, soft but insistent. Ah yes, food.
As much as Spock likes to deny it, he does have the craving for food.
Afterwards, Jim grows too tired to coo, and falls soundly asleep.
Spock decides to venture out and take a survey of the current living conditions of the tribbles on this deck and the one below it. It's dull as far as scientific work goes, but with little else to occupy his time, beggars can't be choosers. At least Jim isn't roaming the hallways and causing trouble. That's always a relief.
But when he returns to his little lair, he finds it empty. Of course. Jim's probably wandered off somewhere by now. Flirting with other tribbles, most likely. That is truly one tribble without shame. Spock doesn't understand why Jim insists they have a bond. It's a metaphor for something, he's sure. He just doesn't know what Jim exactly means by that.
With that thought, he curls up and drifts into a meditational trance.
When he wakes up, Spock immediately senses a drastic change in the environment. The entire deck is disturbingly quiet, completely devoid of familiar and relentless tribble mind chatter he's so used to. His internal alarms immediately go off at max, but quickly a near panic seizes him when he realizes Jim is nowhere to be found either.
It's not rational. Jim must have been rubbing off on him, no pun intended. It couldn't have been. But in Spock's mind is a cold, gripping fear that Jim was taken from the lair in his place. Jim, who cuddled with him and gave him ridiculous nicknames and insisted they'd have children together even though his kind couldn't reproduce. Sure, Jim is insufferable at times; but even more insufferable is a life without Jim, even if it did mean assured continual existence in the absence of overpopulation. Spock wonders why it took him so long to arrive at this conclusion.
As he moves at top speed towards the turbolift, he can only hope it's not too late.
There are three things generally true about tribbles:
1. They love to eat and reproduce.
2. They love to coo.
3. They hate Klingons.
Unlike Spock, Jim is very, very good at being a tribble. Thus, it's only logical that Spock is greeted with the sight of Jim hissing aggressively towards the Klingons before a crowd.
In the midst of the commotion, Spock can only see Jim, cresting in the human captain's hands and shaking with a rage Spock's never seen before.
"You murderous bastards!" Jim is shrieking, "I almost took that grain! I almost killed Spock!"
Not quite understanding what is going on, Spock moves unobtrusively under the shade of a nearby table. He'd have to wait this one out, but seeing Jim alive and well is reassuring enough. And seeing Jim so concerned about his welfare--when he himself would have considered his death no big loss in the light of overpopulation--makes him actually feel warm and fuzzy somehow.
The humanoids exchange more words, people come in and go, and finally the room is quiet again except for the low murmuring of the tribbles. Spock moves out of the shadow cautiously, uncertain what should he say to Jim, who is in the other corner of the room, turned away from him.
But before he can make up his mind, there is the sound of a door opening, and he is picked up by something and dangled in the air. It's the captain, accompanied by another human male.
"Well Bones, look what do we have here." The man regards him with a smiling curiosity. "A most peculiar color, isn't it? I've never seen one like this before--and hey, he's not purring, either."
"Fascinating," the other man says in a decidedly mocking tone. "I think this would be one of those hybrids I've heard about. They have a much cooler temperament than the normal tribbles. Reminds you of a certain pointy-eared Vulcan, doesn't it?"
"Very true. Very true. Although...I think Jones mentioned something about how they can't reproduce?"
"Nope. That's why there're so few of 'em."
"In that case, perhaps we should keep it as a reminder of our favorite Vulcan, a mascot of sorts? With all the other tribbles gone and this one sterile, there would be no danger of another tribble takeover. Besides, I know somebody who would love it."
That last sentence quickly catches Spock's attention. All the other tribbles--gone? He struggles to see Jim's corner, but only finds it empty. In a rare display of panic, he uses all his supertribble strength to break free from the human's hold, landing on the table beneath him.
Must find Jim. Must find Jim. Must find Jim, NOW...
With a soft thud he moves off the table and dashes for the door. Something comes from behind him, however, grabbing onto him and refusing to let go. At first contact he knows instantly that it's Jim, and no other. They hug tightly, as if discovering each other for the first time.
"Ha, gotcha!" Jim sounds tired, but happy. "Never gonna let you go now."
Spock has no reply to that, really. Something inside him melts at that sound. It's most illogical.
"Would you look at that," the captain's voice hovers over them even though they can't see his face. "I daresay our little friend has a friend of his own."
"How endearing," the doctor answers with the tenderness of an iron shovel.
"Feels wrong to separate them somehow. Oh well, let's go check with Scotty for that update."
The rest, as they say, is history.
Two hours later, they are beamed over to IKS Vor'kar. In another three hours, the tribble onslaught of the Klingon ship is complete. By the end Jim decides to call it the Glorious Revolution. Spock thinks it's silly but doesn't say anything. It's gratifying enough to have the golden furry ball back, right next to him.
They are sitting in the captain's chair together now, just the two of them. Around them on the bridge, a petrified Klingon crew is working to get the ship back to the Klingon capital Qo'noS.
On the comm screen, some important-looking Klingon guy is offering profuse praises and extravagant homages to the awe-inspiring tribble race. The speech is punctuated with phrases such as "I, for one, welcome our new tribble overlords."
"I like this chair," Jim yawns, snuggling even closer.
Spock does not coo. There would be no evidence that he ever did.