WE USED TO TALK
Officially, Spock and his other self are corresponding about logic and the building of new Vulcan. His other self poses delicate, intriguing questions to him, and talks about how the few tiny settlements are beginning to settle down, a little.
Unofficially, in their letters and their conversations, they talk about everything and nothing much at all. About the synthesized food, which his other self swears will improve with time, so even plomeek soup will stop tasting like vaguely buttery dishwater and more like plomeeks. Spock doesn't quite believe him, but he's willing to wait and see. They talk about the way that Jim Kirk spends more time than is really rational coming up with names for the mess's baked vegetable omelet. Secretly they agree it's kind of weird tasting, and also if they admit that to Kirk he will never let them live it down. They talk about how Jim will hit on anything that moves and fall in love with it if it seems at all likely to kill him violently - from machines to strange aliens with feathery tendrils for hair.
They talk about Jim a lot, actually. His other self confesses one night, when he's really tired from a long day of teaching children and working to set up areas to drill for water, that he actually brought Jim to his koot-ut-kal-if-fee ceremony and Jim, unbelievably, still didn't get it. He tells Spock how Dr McCoy had to drug Jim, make him act dead, to get Spock to snap out of it. He'd been so angry, he says, his voice quiet and resigned now. He hadn't understood, in the madness of the blood fever, why Jim wasn't letting him bond with him, and then when Jim collapsed and the faint bond had winked out, he'd wanted to die. It He'd honestly thought it was some sort phantom pain, like a lost limb, when Jim came out from under the drug and he began to feel his presence again.
It's like talking to a mirror, so it's almost okay. It satisfies something human in him to be open like this. His other self suggests it more resembles the old thought experiment with the twin who stayed at home and the other who went on the space ship and aged. Only a hell of a lot more weird, as McCoy would say.
Spock tells him about the incredibly awkward, illogical conversation he had with Nyota when it dawned on him that she thinks their relationship is something different than what Spock believed it to be. His other self sympathizes and suggests some music she might like, as a I'm Sorry I'm A Vulcan and Didn't Realize You Had An Emotional Attachment To Me present. Humans like receiving presents.
His other self tells him about when Jim really died, because it's logical to be prepared. He says there's no way to be ready for it, not really. He confesses to a feeling less like a phantom limb and more like Jim is hanging around just beyond the limits of his sight, waiting for him to be done with life. He says that Jim seems to be a lot more patient now that he's dead.
Spock suggests that he now lacks adrenal glands.
His other self agrees that is sound logic.
It reminds Spock of the last time Jim did something suicidally insane and lived anyway. He tells his other self about it, and how Bones had somehow managed to rush beside the gurney, keep pressure on Jim's stab wound, and curse at him fluently, all the way to the medical bay. They talk about three-dimensional chess and Jim's equally insane playing. He says he's thinking teaching his Jim go. His other self says he could never quite bring himself to teach his Jim go, on the grounds that anybody who played chess like James Kirk could easily drive Spock to hysterical tears over his idea of go strategy.
Spock says it's a chance he's willing to take.
They don't talk about their own conversations with Jim, even though Spock knows that Jim talks to his other self. There's a puzzle in Jim's quarters that is obviously Vulcan, and not from him. That's acceptable. Maybe it wouldn't be to Jim, if there was two Jims and only one Spock, but Vulcans know how to share limited resources.
When Jim leans against the corner of his workstation and says, "What do you and the old man find to talk about all the time, anyway?"
Spock just looks up at him, gold in the cool light of the science lab, and says, "Nothing to interest you, Captain."