Martha reaches the inside of the TARDIS first, and sags against one of the coral columns as the Doctor slams the door shut behind them. She clutches her stomach and breathes slowly in an attempt to relieve the stitch in her side. He's out of breath, too, she notes with some measure of satisfaction.
"Running for our lives," she says. "Why can't it be skipping for our lives or something?"
The Doctor smiles; a rare thing. Martha likes the way it lights up his eyes.
"Frolicking for our lives, then?"
This draws out a laugh or two-another rare occurance-and it makes her want to push the joke further, keep that smile.
"What about hopping? Hopping for our lives, there's a new one!"
She realizes she's said the wrong thing before it's even out of her mouth, curses herself inwardly as the giddiness leaves his eyes and the laugh is replaced with a forced smile. The Doctor turns his back to her and starts pushing buttons on the console.
"I did that once," he says after a while by way of explanation, half turning towards her. She can tell he's doing that infuriating thing where he's looking at her but he's not seeing her, not really. It makes her angrier than usual today.
"With Rose?" she asks. She's being unforgivable. She doesn't much care.
He turns back to the console, saying nothing. Martha already knows the answer. And now she's hurt him; it leaves her feeling less satisfied than she thought it would, and all the anger drains from her, leaving her exhausted. She hates this. This game they play, let's-see-how-many-times-you-can-make-me-feel-inferior-and-how-many-times-I-can-reopen-your-old-wounds.
She'll never be good enough for him.
Martha moves away from the column, trying to avoid looking at the Doctor's blue-pinstriped back, and says quietly, apologetically, "Tea?"
The smile he gives her in return is genuine, just a little lacking in the happiness department. "Thanks."