This just sort of furthers the main, two-word adjective he's been using to describe her since she started on board: "Not Rose." Rose would've spent less time trying to drill knowledge from him and sort of figured it out as she went along. Martha, on the other hand, is the bookworm, the studier, and she needs to know before she experiences.
Which is completely and totally annoying.
How old are you? When's your birthday? How are Timelords born? What size shoe do you wear? Do you lot have sex? (This last one invoked a rather awkward conversation involving much blushing, much coughing, and many unnecessary headscratches.)
He doesn't understand these questions, they all seem so completely ridiculous. What did it matter when his birthday was, or what size shoe he wore? They were things that just sort of melted into the background of the rest of the universe. But still, she asks. And he won't admit he likes her company, won't admit that it's pulled him out of sitting around in his TARDIS for weeks at a time, talking to no one but himself and the TARDIS, won't admit that he's afraid she'll leave him, too. So he answers her questions, as best he can.
Today, it's a new question.
"Who's your best friend?" she asks, "Besides Rose, I mean, I know...she was your best friend for a long time."
He considers pelting out a deep, long-suffering sort of sigh, but realizes it's really a futile waste of breath. She's still going to ask, and if he doesn't answer, she'll just assume the worst or ask at a time where he can't think of a delicate response.
His eyes avoid hers, and he looks down to the console, "I don't know," he says, "The TARDIS, I suppose."
"Your ship?" she asks, "You consider your ship to be your best friend?"
He nods, and feels the TARDIS in his mind swell with pride. It has companions within it, but the only one that feels it as a being is the Doctor. They are the last of their kinds, and that gives it the feeling of a bond.
"The TARDIS and I have been together for....ooooh, just around 900 years or so. Tends to make one consider the other a best friend, I think."
Martha is confused, and she's pulling one of those absurdly endearing faces that shows just how confused she is.
"But...the TARDIS is a ship, it's not a person. You can't be a best friend with something that isn't alive. You can love it, cause it's your ship, but it's not a best friend."
The Doctor does sigh, at this point, but it's not really because of her. It's because he hates starting from scratch, hates the things she doesn't know because it just keeps reminding him of how Not Rose she is.
He holds out a hand, and she looks awkwardly at it.
"Here, give me your hand," he says. She complies, of course. He has a feeling that if he told her that standing on her head and singing the Gambler until she turned blue would make her understand him, she'd probably do it. That's another way she's Not Rose. Rose could accept simply not knowing, or simply figuring it was part of him she didn't understand. Martha can't.
He takes her hand and puts it onto the column above the console. She's not tall, and has to stand on her tiptoes to reach it. He flattens her palm against the smooth, glass-like surface, beneath which the crystals shift and move.
"What do you feel?" he asks.
"Vibration," she replies, "Electricity."
She bites her lip. It's a school time quiz, and she's trying to figure out the answer. She's judging him to see what the correct answer is, not what she thinks, and that just shows how Not Rose she is, as well.
"The movement of the crystals?"
"Warmth, like heat."
And there's another face, frustrated this time. "I'm terrible at guessing games, Mr. Smith, why don't you just tell me?"
He can't help it; he smiles, and then presses his palm against the back of her hand.
"The TARDIS has two heartbeats," he says, "They're faint, but they're there. They beat just opposite mine, do you feel?"
She looks at their hands (something strange in her expression, he can't figure out what), then closes her eyes, concentrating on what she feels. He can tell the moment she feels it, because her eyebrows hit her hairline, and her eyes snap open in surprise.
"Oh my God," she says, "It's alive. The TARDIS is alive!" She turns to the Doctor, "How's it do that? How---"
"There isn't a how," he says, pulling away, "It just is."
"Can it feel us?" she asks, her hand still on the column, "The TARDIS, does it know we're there? Does it have a gender---"
"Oh, honestly, you're not going to start bombarding me with questions about the TARDIS now, are you?"
She snorts, "How'm I supposed to feel? You've only just told me I've been living inside something that's living!" She pulls back from the console, and he can swear he can see the wheels in her head turning. She's comprehending every answer he's given her, she's putting puzzle pieces together.
She's like Rose in that way. Maybe she's simply like Martha that way.
"Why does the TARDIS have two heartbeats, beat opposite yours? Is it..." She pulls an awkward expression, and he knows she's about to ask something silly, but lets her anyway. "Is it like, the female of your species?"
That invokes a laugh from him, and he realizes that must've been the first time she's ever made him laugh, she looks so startled by it.
"No, no, no, TARDISes are their own species, and this one, well, she's the last of her kind, too," he says, stroking the console lovingly, "No, we're...it's...complicated."
Martha sits back down on the chair, crossing her arms, "Try me. Come on, Doctor, I want to understand."
He sighs again, and he figures he should probably keep track of how often she makes him do that.
"The TARDIS and I are symbiotically linked, helps me know when she's damaged, helps her find me when I need her."
"Symbiotically, like you need it, and it needs you?"
He gives her a look, "That is what the word means, Martha." He shakes his head, "When she was young and I was very, very young, we bonded. I've got a symbiotic nuclei in my head, and she is part of me, in turn."
She nods, "You keep saying 'she', though, is the TARDIS a female? Do they reproduce?"
"What is your obsession with alien reproduction?"
"I'm just trying to understand!"
"The TARDIS isn't really female. Not exactly, it's just...what I call her. TARDISes don’t have gender, they're...grown, not born."
"Like a plant?"
"Sort of, do you want me to explain why the TARDIS is my best friend or not?" She silences, so he continues, "The TARDIS and I have been through an awful lot, not just the bonding experience, and the War, and all that." He looks away from her, into the console, to the heart of the TARDIS somewhere beneath that he's never looked into, but he's seen, all the same.
"I can feel her," he says, "The TARDIS, I can feel her, I can feel it when she's hurt. I find the problem, and I pull out the sonic screwdriver and fix it. Sort out the wiring that's misfiring and replace it. I can feel when she's better, too. When she's...scared. When she's aching, when she's lonely. She remembers every person that's ever lived in her, you know? She remembers every argument, every battle, every toe that's stubbed on the stairs leading up to the lavatory."
A small smile appears on Martha's lips. She stubbed her toe the first time going up there, too, so she understands. Or maybe it's something else. It's the same expression she wore when he first told her about Gallifrey. Awed, like his words are painting a picture for her, and she can see it, even though she's not there.
"She can feel you, too," she says, "The TARDIS."
His eyebrows knit together, and he has no idea how she figured that out.
His expression must tell her that, because she nods. "The other night, when I found Rose's jacket in the wardrobe room, you got upset but didn't say anything, and the TARDIS got all cold and dark. I thought something wasn't working, but if it wasn't you usually fix it. The TARDIS wasn't broken, though. It was just grieving with you."
The word hurts. Grief. But it's accurate, and he can't fault her for accuracy, no matter how annoying it is.
"Friends share pain," he replied, "The TARDIS and I have had our fair share, over these years."
Martha nods, and gives the console a small pat that's wary, but with the attempt to be accepting. The way she treats him, sometimes, too.
He can feel his ship, in his mind. It likes her, a lot. She's Not Rose to the TARDIS sometimes, but she's starting to grow on it. There's a sort of plea: Don't make her leave. Not just yet. Give her some time to be Martha instead of Not Rose.
He would argue, but that's no fun; arguing with one's best friend.
Muse: The Doctor (Ten)
Fandom: Doctor Who
Word Count: 1,581