1. I usually think in the TOS universe, so I'm thinking very specifically of the Uhura who sang that song to Spock in "Charlie X" and of the Uhura who tried to flirt with Spock in "The Man Trap" by saying, "Tell me how your planet Vulcan looks on a lazy evening when the moon is full," only to be told "Vulcan has no moon." But if you prefer reboot Spock/Uhura, this might work with them, too, though that Spock is far less controlled than TOS Spock.
2. Since Spock is an honorable man, I'm assuming that this story takes place after his divorce from T'Pring in "Amok Time," but perhaps not very long after that. ;-)
3. Star Trek belongs to Paramount (legally) and Gene Roddenberry, Gene Coon, Dorothy Fontana, and Bob Justman (morally). I'm just borrowing the characters for a moment, since they seem to have taken up residence in my strange little mind. :-)
Trust and Control
Spock could really hurt her, Nyota knows, if he ever lost it. Not that he ever would. His control is legendary; there are moments when the fate of the entire ship rests on it, and he has never let them down. But if. If he ever lost control, he could really hurt her. And that's part of the thrill. It's not that she actually wants him to really hurt her, because she doesn't. Mostly. The sane part of her doesn't want him to really hurt her, and not just for her sake, but also for his. But the edge of danger — danger she will almost certainly never actually face — that edge calls her, thrills her. Almost certainly she will never face that danger — "almost," there's another word, like "if," that tantalizes her.
Spock needs his control, to function properly, to feel Vulcan, to be who he is. She knows it cost the child Spock so much to gain that control, and she knows that even today, it is not as effortless as he makes it appear. She knows he loves his control — more, probably, than he loves her — almost defines himself by it, as if his control and his identity are one. But she also knows some tiny part of him is tired of it, wishes he could drop it, wishes that being the perfect Vulcan required no effort. That part of him is very tiny — tinier, perhaps, even than the small part of her that wishes he would really hurt her — but tiny is so very different from nonexistent. He wouldn't value his perfect Vulcanness so much, perhaps, if it actually required no effort. But all people are complicated, and this half-human, half-Vulcan hybrid may be the most complicated she has ever met. It's part of why he fascinates and enthralls her.
She isn't completely certain why he likes the game as much as he does. She'd feared at first that he was only playing it to humor her, but as time went on, it became quite clear that he was not, that the game calls to him as much as to her, although he had needed for her to be the one to suggest it. And so they play this game, the one where they dance along the edges of his control, the one where they tantalize each other with the fear — or is it the hope? — that he will lose that control and really hurt her.
Vulcan possessiveness seems to feed the game, but the primary fuel is Vulcan passion. Most people think "Vulcan passion" is an oxymoron, or maybe something cold and rational that Vulcans apply to science. But she knows that Vulcan passion is down there, buried deep in his psyche like lava beneath a mostly-dormant volcano, but present enough to warm her when she's close, present enough to scorch her if she dares to get close enough. But it's the possibility of an eruption that fascinates her. She doesn't want to be immolated in lava, not actually, not really. But the possibility, the if — she needs that to be there. And to have all that passion actually directed at her ... it might be worth being really hurt, if she could see that, could feel that, just once. And she knows he is aware that she feels this way, knows that this attitude from her is part of what picks at his control, loosens it, makes the danger go from nearly nonexistent to simply improbable. If he ever does lose it, will it be her fault?
There are other places — safer places — where she could exercise her skill at communications, just as there are other places where Spock could make observations and conduct experiments. But they're both on the Enterprise, not just because they're the best, but because they're explorers, and the unknown calls to them. She doesn't want anything bad to happen to the Enterprise, in the same way that she doesn't want him to really hurt her, but they wouldn't be having an adventure unless there were some risk. Picking herself up from the floor of the Bridge once every month or two reminds her that it IS an adventure, that she's not pulling in messages from the next planet over but from unknown aliens, from ships in trouble, from things so strange that it's not clear if they're even alive. So maybe that's why they're both into the game, because they wouldn't be on the ship in the first place unless they wanted that adventure, that edge.
They had started out playing like humans, with rules and limits and safewords all carefully spelled out. But when your partner can read your thoughts and feelings simply by brushing your skin, the external controls aren't just unnecessary; they become a distraction, an annoyance. She doesn't really need a safeword because Spock will always know exactly how close she is to the place where strong sensation becomes bad pain, to the place where voluntarily giving up control becomes feeling like an actual victim, to the place where what they're doing crosses the line from thrilling to too much. Knowing intellectually that she's safer trusting to Spock's ability to read her than she would be to her own ability to call safeword doesn't alter the emotional reality that giving up those external controls feels dangerous. And Spock seems to understand that, more than she thought he would. Spock understands a lot of things better than she'd thought he would. But then, understanding and knowing are what Spock does, very nearly who he is.
Today's game will be different from their usual, because they're on shore leave. They've rented a cabin in the woods, a stretch of forest that's all theirs for the week, and this will be different from presenting herself at his quarters at 20:00 and leaving by 22:00 so that they can both be adequately rested for duty the next day. It's different from his having to be extremely careful about what he does to her delicate human body, because she needs to be able to give the captain peak performance the next day. She's asked him to go farther than he usually takes them, now that they have a week off, and the careful blankness that greeted her request was better than a growl would have been from another man. He's excited enough by her request that he had to hold tightly to his emotionless Vulcan mask, and she can't wait for the game to start.
She didn't want to know when exactly it would begin, had asked that he simply start when he was ready. She'd thought that would be a nice change from the regulated life they led on the ship. And now she's spent the morning walking in the forest, admiring the foliage, listening to the birds, and alternating between trying not to think about this game they play and being unable to think of anything else. Of course he wouldn't take her the instant they got to the cabin, of course he'd want to draw out the anticipation, make her wonder when they'd begin, throw her a little off balance. She'd asked to give up control, after all, asked to be played like a Vulcan lyre, and she needed to let him do things his way. A dominant Spock was so insanely hot that giving up control was no hardship, except for now, while she was waiting. "Soon," she thought, "Let it be soon!"