He doesn't look up from where he's reading on their couch, but she knows that he's heard her by the way he tilts his head slightly in her direction.
"Spock, are you sterile?"
He turns his face toward her, moving his head only, and lowers his PADD, eyes wide but expression otherwise unchanged. She's sitting at her desk to the left of the couch, her body facing him, legs swung uncomfortably over the chair's edge. They are bathed in a pool of golden light in a quiet moment between shifts. It's hot, as hot as it always is in their quarters, and the air is a thick, smooth cloth wrapped around them. She feels like summer nights under the African sky.
"I…I do not…that is to say, my heritage is unusual, but has been replicated many times in Terran history-"
"Spock, a simple yes or no, please."
"Why do you inquire?" He is earnest, concerned. His eyebrows have drawn together infinitesimally and Nyota sees fear in his fondue eyes. She is suddenly embarrassed, and looks away.
"I just know that most hybrids are. Like you said, cross-species mating has occurred many times, but the offspring rarely go on to have children of their own. It's just, I mean, biologically speaking-"
"Yes." He blurts out.
She is taken aback; she was expecting this answer, but expecting it and having it confirmed are two different things.
"Yes. As far as I am aware, I am infertile."
"Oh." They stare at one another. She doesn't know what to say. She turns back to her desk in embarrassment. Internally, Nyota is cursing herself. She knew she shouldn't have asked; Spock hates talking about his mixed genes.
She looks at him out of the corner of her eye. He is turned back to his PADD, but Nyota can tell that he's not reading by the way that he is breathing. She knows him inside and out, she doesn't even think about what he's experiencing anymore because she can just sense it. He's practicing one of his meditative breathing techniques.
They continue in silence.
She can't stand it.
She gets up and strides quickly over to her lover, cradles his face in her hands, and bends to kiss him. Spock rises into her touch, and for a moment they are poised awkwardly between standing and sitting. She takes a step back, still wrapped around him and he follows her, drawing her near. Nyota pushes everything at him, using the connection to say what cannot be said out loud.
I love you, I need you, I don't care that we can't have children, I don't need them, all that I need is you you you you I'm not unhappy I'm not sad I didn't mean to make you feel like you aren't enough you are everything I love you.
A month and a half later, she braces herself against the bathroom door with one forearm, clutching a pregnancy test in the other, and sobs.