"How do you do it?"

"Do what?" he asks, even though he thinks he already knows, and Martha Jones is brave and clever and altogether brilliant, but she's also persistent, and at some times that can be a very good thing, but at others he really wishes that she would just give up, because he's not her patient and she can't fix him and she's just going to end up hurt.

"Laugh at things like that." She sounds torn between disgust and admiration, and he isn't sure which one he prefers. "People had died, and we could've been next, and that . . . thing was threatening and yelling and you stood there and laughed."

She was terrified, he knows, but whether it was of the Grantin or of him he has no idea.

"Dunno," he says as casually as he can, tugging absently on an earlobe. "Guess I don't see why not. I mean, sure, I could treat everything like the dark and serious matter that it is, but that'd get awfully depressing, don't you think?"

Her next question comes in a rush, like she's trying to say it before she loses her nerve.

"Did you ever laugh at the Daleks?"

His hands freeze in their tinkering as his mind flashes back to an underground bunker in Utah, and the horrifying, mind-burning, gut-wrenching realization that they survived, they survived, and his people's death, his world's destruction, the screams that constantly echoed in his ears and the flames that burned behind his eyes, it was all for nothing, but – wait. It was helpless. A Dalek, one of the destroyers of his people (though it wasn't, not really, that was him in the end), and it was helpless. He remembers the laughter that ripped itself from his throat, not just manic but hysterical, mad – and then there was light and pain and anger and loss and Rose, and then – it was over. Another memory; another nightmare; another scar.

And then they were back, punching holes in reality among the Cybermen and Jackie and the goddamn humans who could never leave well enough alone and there it was again, that laughter, dark and desperate and just as mad as before, even if this incarnation is better at hiding it (or worse, he's never quite sure) –

Martha is watching him worriedly – she worries about him a lot, and he wishes she wouldn't, because he's not worth it, he's really not, if she knew what he's done – and he realizes that she's still waiting for an answer.

"Yeah," he says, trying to keep his voice light and not quite making it over the sudden tightness in his throat. He tries again. "Yeah, I have."

She nods, looking thoughtful, and he knows that she's absorbing the information, clicking another puzzle piece into place – but oh, it doesn't work that way, because Time Lord puzzles are never in any less than four dimensions and they're almost always a trick, and even he can't seem to put himself back together anymore and he's sure that some of the pieces are missing, lost in fire and the silence in his head . . . .

She's still watching him, so he makes an effort to look focused, even though he's forgotten what he was tinkering with in the first place. Oh, that's right, the flux capacitor (it's actually just a part of the temperature regulation system, but he started calling it that centuries ago and he can't be bothered to remember its real name).

"But . . . why?" she finally bursts out, and he relaxes, because this, ithis/i he can answer. Not with the whole truth, because he never gives the whole truth (told her about Gallifrey, told her that it burnt, didn't tell her how he ran away and was called back and was executed and exiled and elected President and ran away again, didn't tell her that he was the one who pressed the button, killer of his own kind, Destroyer of Worlds), but with some of it, at least.

"Keeps them off balance!" he says cheerfully, and manages to hit the mark this time. "Daleks and dictators and big scary monsters, they always expect you to cower and grovel or make dramatic speeches and whatnot. They're never quite sure what to do when you laugh in their face – or eyestalk, as the case may be. Can buy you crucial seconds."

"Makes sense, I guess," she says, and she sounds a little doubtful, but he asks which book she's reading, even though he can see it perfectly well from where he's standing, and oh, he's been meaning to meet Jane Austen, never quite got around to it, and how does Martha fancy a trip to regency England? And then there're dresses and aristocracy and an alien invasion thrown in for flavor, and even Martha isn't that persistent, so he never has to tell her the whole truth.

He never has to tell her that, more often than not, the laughter is to keep from crying. To keep from screaming and raging and falling and breaking and letting go, to keep from tearing across the Universe like her sometimes feels like doing, burning every planet that even looks like Skaro. He's a Time Lord – the Time Lord – and he may not be omniscient but he knows this Universe like an old sock, knows where all the holes are, knows the threads to pull to make the whole thing unravel, and some days, some days when he's lost everything again and no one cares because there's no one left who even knows that he exists, and those stupid, little humans are killing each other over religion and arguing over politics and complaining about the price of petrol and they have no idea what's been sacrificed for them – some days he almost wants to.

But he wouldn't, not really, because he loves humans, brilliant, wonderful, stupid humans, who think with their hearts and their souls and their dreams, even though their worlds are too small and their lives are far, far too short and their skin is nearly hot enough to burn.

That doesn't stop him from wanting to, sometimes. So he laughs, instead. And if, when he does, people think he sounds a little mad –

Well.

Humans are very perceptive.