It is a different kind of secret from those she has already, like the hidden bottle of perfume under her bed, Artemis and Aphrodite stowed deep into her locker, and the real one, the secret she will always carry, that she killed Zach Adama as surely as if she’d put a bullet in his head.
This is different. This is a secret nobody knows. It is a secret she stumbled across in a deserted corridor and dragged to safety in a holding bay where no-one ever comes, and visits every day, twice if she can manage it, so she can make sure it is still there.
Her secret is not a man. When she first pushed, pulled and hauled him to a place where no-one would ever find him, she wondered why she was doing it, why she wasn’t raising the alarm and arranging for Baltar and his detector to be down here post-haste. “Are you a Cylon?” she hissed in his ear as his body went limp, and his eyes opened. They were blue.
“What is a Cylon?” he murmured, and she was taken aback.
“The enemy,” she said, and when his face didn’t clear, “Robots that look like us.”
Every movement seemed to be a struggle for him, every tremor in his slender hands an indication of weakness, but he reached out and pulled at one of her wrists so her palm was flat on his chest, on the left side. She felt the slow, steady beat through skin and fabric (his clothes, too, are unlike any she’s seen in the months since she left Caprica), but she kept her eyes fixed on his. “That doesn’t prove anything,” she said softly, dangerously. “They look – and feel – like us.”
His grasp hadn’t slackened. He moved her hand across to the other side. And after a second she felt what he meant her to feel: the second heartbeat, steady on the right side.
“You’re not human,” she breathed, and snatched her hand away as if burned.
There was no reply. His eyes were closed again, his breathing fast and uneven. Whatever he was, he was weak, and Kara let him lie.
So the newest secret of Kara Thrace is not a man, and not a Cylon. He is something and someone different.
*
          
          She goes back after a day and she takes food and water. He has barely 
          moved, but his eyes open as he comes near, and she fancies she sees a 
          half-smile flit across his face. Eagerly, he reaches for the flask and 
          she notices his lips are dry and bleeding into the water, but the 
          food, stolen from supplies, goes untouched. 
          
          “What happened to you?” she asks, and she knows it was something 
          terrible without asking; she has seen that weakness, that look, too 
          often in this time after the apocalypse. He turns his head to look at 
          her, and merely shakes his head.
          
          Kara stands up. She moves to the other end of the quiet holding bay, 
          and turns round. She walks swiftly back, boots banging on metal, falls 
          to her knees in a swift, practised movement and aims a punch straight 
          at his face.
          
          Her fist just misses, and he flinches and rolls away, drawing his legs 
          upwards. Kara stands still for a second before she goes back to sit 
          beside him. “You’re not a fighter,” she says conversationally.
          
          “I’ve got soul but I’m not a soldier,” he says weakly, and gives that 
          half-smile again; the phrase must have some significance for him that 
          she is missing, and she frowns.
          
          “Or maybe,” she says, thinking aloud, “maybe you’ve been hit so much 
          you don’t hit back any more.”
          
          “Maybe,” he says, softly, and because she can’t help herself, she 
          touches his hair, blonde and wet at the tips from where it has fallen 
          in his mouth, and brushes it away from his face. 
          
          The gesture surprises both of them. She gets up very quickly after 
          that, leaving him lying where he is, and takes the flask to be 
          refilled but doesn’t touch the food. Maybe he’ll want it later.
          
          As she reaches the door, she hears him murmur, “Doctor…”
          
          She turns to face him. “I haven’t told anyone about you, and it’s 
          staying that way.”
          
          She leaves.
          
 
*
          
          This time he seems better. He is sitting up, has eaten the small 
          amount of food she left for him, and his eyes are still too bright and 
          lustrous to be quite healthy, but better. Although she thought at 
          first that he was asking for a doctor, it seems he was referring to 
          himself, or trying to.
          
          “Doctor,” she says. A strange name to go with a strange nature, for 
          Kara believes that this this person whom she has helped is something 
          unique in her experience: an innocent. Appearances can be deceiving, 
          but the gentleness in him seems distinct from the weakness, as though 
          he is like this, soft-spoken and doe-eyed even when not defenceless on 
          the floor deep within an ancient battlestar.
          
          “Why did you help me?” he asks, frighteningly direct in the way he 
          looks right at her.
          
          “Because you needed it,” she says, baldly. She doesn’t tell him about 
          the world he will presently find himself in, with human existence in 
          pieces all around. She doesn’t tell him about how tired she is of 
          being Kara Thrace, Starbuck the Viper pilot and on the forefront of 
          defence against the Cylon raiders, or how sometimes she just wants 
          something that isn’t part of the big shared communal military effort, 
          something private and all of her own. 
          
          She could make him all her own. She would be lying if she said she 
          hadn’t thought about that, even as he lay there and stared at her 
          through innocent blue eyes; she wants to see how human he is under his 
          clothes, following the line of creamy white skin down from his neck 
          and over his shoulders, under the ragged shirt and coat.
          
          She reaches across without thinking, now, and pulls at the torn, 
          wilting green sprig at his lapel. “What’s this?” she asks.
          
          “Celery,” he says, and his voice is still quiet but has a great deal 
          more strength beneath it. “You put it in salad.”
          
          Kara laughs suddenly. Of course you do, she thinks. She did, whenever 
          she bothered cooking at home on Caprica. Zach used to pick it out and 
          leave it at the side of his plate.
          
          “Who are you?” she asks, hoping to startle the truth out of him.
          
          “The Doctor,” he says, and that is all he will tell her.
          
 
*
          
          The last time she visits him, it is clear he has been walking about, 
          pacing perhaps, up and down and up and down like a caged animal.
          
          “What’s your name?” he asks her the second she arrives.
          
          “Starbuck,” she tells him.
          
          He shakes his head. “I know an alias when I hear one.”
          
          She wants to tell him that it isn’t an alias, it’s a callsign and what 
          the frak does he know about it anyway, but she can’t bring herself to 
          say all that. “I’m Kara Thrace,” she says after a while. And because 
          it seems necessary, she adds: “I’m a pilot.”
          
          “I knew a girl like you who flew, but she wasn’t a pilot.” He frowns, 
          and to her he seems human. “Thank you, Kara. I won’t forget what 
          you’ve done for me.”
          
          Once again, she has to ask who he is and where he has come from, how a 
          civilian man with two hearts, with ragged clothing and shaking hands 
          end up on the flagship of the fleet, but all she says out loud is, 
          “What happened to you?”
          
          “I was lying at the side of the road, and someone crossed over to help 
          me,” he says, and the words seem to mean something to him if not to 
          her. “And now I must go.”
          
          “Where?” she asks, wondering why she cares.
          
          “Somewhere else.”
          
          She recognises something in him as he stands there, shifting from foot 
          to foot. That constant wanderlust is something she sees in the mirror, 
          that need to go and be gone. She is here, with the rest of the human 
          race at the end of the world with nowhere to go, but she thinks that 
          for him, this encounter has been an interlude between something and 
          something else. 
          
          “If I close my eyes, will you be gone when I open them?” she asks.
          
          He laughs, and it is the first time she has heard him laugh. “Perhaps. 
          Goodbye, Kara Thrace, and thank you.”
          
          She doesn’t close her eyes, and yet he’s gone anyway; the next time 
          she comes down, there is no sign he was ever there. There are no 
          traces of unusual activity reported anywhere on Galactica, and no 
          Viper has been taken from its bay, but he is gone all the same.
          
          Kara forgets him, forgets he called himself the Doctor, and doesn’t 
          grieve for something else lost.