"Why Uhura Doesn't Like Traveling with the Doctor"
When someone invites you to travel with him in his space ship that also happens to be a time machine, it's only natural to agree without hesitation. But Uhura wishes she hadn't.
It's not the mild embarrassment that she feels every time they land and she knows that the outside of the ship is a wooden police box, instead of the gleaming, gigantic beauty that she loves. It's not the fact that, the impossibly huge interior always feels empty, especially when compared to the bustling halls of the Enterprise. It's certainly not the ridiculous amount of turbulence and being knocked off her feet constantly. She's used to that.
What really bothers Uhura is the language. She discovered to her dismay on the first planet that they landed on that the TARDIS automatically translated the alien languages into her brain. And she's not too bothered by the fact that the skill that she's the most proud of, that has always come so naturally to her, has no purpose here, because she is sensible, and can see how useful it is to be able to communicate with the various aliens that they encounter. Not that being able to talk with them makes the aliens any less likely to try to kill them, especially since they tend to not like what the Doctor has to say. But still, she tries to listen every time for even the faintest echo of the real language beneath the TARDIS's transmission into her brain. She never hears anything.
Even before she joined Starfleet Academy, Uhura had been surrounded by different languages. She learned Standard in school of course, but her parents had never tried to learn any language other than their native Swahili, and the little boy down the street had only spoken Spanish, and whenever she went shopping, she could hear the music of hundreds of different languages flowing like a sea around her.
On the TARDIS, though, there is only Standard. It is relentless, and it makes her uncomfortable and unaccountably nervous, as though there is something essential missing from her life. When she dreams, she hears her grandmother singing an ancient lullaby and Spock reciting a Vulcan poem, and the joyous incomprehensible racket of a marketplace. But even these dreams stop after awhile.
In an unconscious defense, she finds herself thinking in Chinese, muttering to herself in Arabic, and speaking to the Doctor in French. He doesn't notice. She's not surprised. But still, after awhile even this is not enough, and she finds herself restless, missing the soothing lull of words that she doesn't know the meaning of, just the intention.
The Doctor isn't exactly oblivious, but she knows that he chooses to ignore the fact that something is wrong, because he's terrified that she'll say that she wants to leave. She doesn't. Because as much as the ship frustrates her, she's enchanted by the opportunity to travel to any planet she can imagine, and to any time that she chooses. But she can feel herself slowly going insane as her languages slip away from her, no matter how tightly she tries to hold onto them.
So finally she goes to him. She tells him that she loves travelling with him, but there is something else that she needs, and she holds out a hand to stem the fear that she can read on his face, because even though she understood the words that everyone said, understanding body language was every bit as important and she had managed to retain that skill. When he realizes what she is asking for, even someone without Uhura's proficiency would be able to recognize the naked relief tugging his lips into an irresistible grin.
He takes her by the hand, and leads her to the Control Room. The sonic screwdriver appears from nowhere, as always, and he points it at a section of a panel. Then he speaks. And what she hears isn't the Estuary English accent that she's become familiar with, but a deep, rich, almost tangible language, full of circles and mathematical symbols. And she smiles, and he smiles back, and she lets his voice flow over her, warming a part of her soul that she'd thought lost forever.