Uhura and Spock mind meld only once in their early relationship; five nights after Vulcan was destroyed. Uhura is aware of what occurs during a melding, of course. Telepathy is one of the more known about facts concerning Vulcan kind, even with their well-known propensity for secrets.
It is dark, and late. Spock is gentle- nervous, even- and he clearly needs this. She can tell at once even without being able to see his face that the man has been waiting to ask for the last five days and nights, no doubt waiting out of some ridiculous wish to avoid putting pressure on her.
So of course she agrees. How on Earth could she not? The peculiarly Vulcan connection of melding means something new and precious to him now the planet's destruction has sunk in, and denying him that is anathema to her.
Three fingers are laid on her temple, white-hot and barely there the touch remains so light, but then she cannot feel her body any more.
The feeling is absolute and all-encompassing. Cold grief, hot rage, more guilt than Uhura has felt in her entire life combined. The experience lasts about a minute and she feels every fraction of a second as though it were an hour, dimly aware she is breaking into a cold sweat and shivering somewhere but not here, here there is only darkness where there should be soil, a planet hanging in the sky, something except this void-
She still cannot see his face when she surfaces, save for a tiny glint of light reflecting off one eye, entirely inscrutable. His expression seems unchanged from what she can see. The breathing just audible within the silent room is even as he removes a hand from her face.
Still in a cold sweat, she shivers in his arms and wonders if he felt her own mind as she had felt his. Wonders if that helped assuage that tornado of loss he had shown her, and hopes with every fibre she has to spare it did.
And finally, resolves to make sure it did, no matter what cost it makes her pay.