It's shaggy, shapeless and black, with a face like a mask of metal; it stares at them and what it sees goes somewhere else, on a screen. Rosita hides behind the Doctor, who brandishes his screwdriver happily. "I've been hunting this beast for a good fortnight. Now step back, sir!" It jumps past them, to the wall, dancing up ten yards or more before looking back at them. John Smith recognizes the idea of the thing, if not the thing itself: "Some sort of primitive conversion, like they took the brain of a cat or a dog." He knows it's the Cybermen, again. So does the Doctor.
"Well, talking's all very well. Rosita? I'm ready." Ever faithful, she hands him the lasso, and he nabs it easily. "Now then," he says, speaking from a deep and nearby place in his memory, "Let's pull this timorous beastie down to earth." It crawls up the wall, sickening, and pulls him up instead. John crosses the distance to the wall easily and adds himself to the rope as Rosita screams at them both. The beast jumps, intruder window, and the boys dangle. The Doctor suggests that John Smith let go, but he promises never to let him out of sight: "Don't you recognize me?" He doesn't. The Doctor doesn't recognize John Smith at all.
"This is hardly the right time for me to go through my social calendaaaaaaaa" he screams, as the beast pulls them up and through the window, across a long and dusty empty floor. They are boys on sleds, on holiday, laughing as they crash through the house toward the other window, where the beast intends to jump again. The Doctor wraps the rope around his hands, refusing to let go, a grin still dancing on his face. As they reach the crisis Rosita chops the rope ahead of them, and the beast disappears. John Smith and the Doctor stand up, aching, and laugh. They throw their arms around each other.
Rosita drags her axe back to them, scraping along the floor, and her look is so darkly dangerous that it sends the boys off in fits again. She leads the way back downstairs, to the courtyard. "Well, I'm glad you think it's so funny. You're mad. Both of you. You could've got killed!" The perfect team. "But evidently we did not!" says the Doctor expansively, and John Smith falls in love.
"Oh, I should introduce Rosita. My faithful Companion, always telling me off..." John Smith knows, and commiserates, to another hideous glance from her, like What. He considers her briefly: "Rosita? Good name. Hello, Rosita." She gives him no ground. She has no idea what he sees, when he looks at her: Rose's name and heart, Martha's humble strength and style, Donna's wise and absolute rejection of all bullshit. If the Master's wife was an inversion of all Companions, the Next Doctor's is a composite of them all. There's a reason but he can't see it yet. All it does for now is hurt: "Now I'll have to go and dismantle the traps!" she shouts, and heads off stomping while the Doctor shrugs. "All that for nothing! And we've only got twenty minutes till the funeral, don't forget. Then back to the TARDIS, right?" Oh, Spaceman.