She stares at him, still holding the watch.
"Become human," she says flatly. Incredulously. She has one eyebrow raised, almost as if she's waiting for the punch line, but he's serious.
"Right," he replies. "Camouflage! They never actually saw me, so if I become human, they won't be able to pick me out of a crowd of other humans. They'll only live another three months, so we just wait until then and open the watch. Easy!"
She's still staring at him, the exact look she uses whenever he's had an especially daft idea. Slowly, she says, "You said they can follow us wherever we go. So they'd follow us wherever we went when you become human." Her voice has an odd little catch when she says "become human", but he doesn't want to think about what that means.
"Well, possibly," he admits. "Or maybe more than possibly; they're very determined -- anyway!" He coughs. "It doesn't matter if they follow us, because they still won't be able to find me. And if they do, then I can just open the watch and take care of them."
"So why don't we just skip the whole 'becoming human' thing and take care of them now?" she suggests. He opens his mouth to explain, but then she continues, loudly. "I think that's a much better plan than shovin' everything you are into a watch and hidin' and hopin' they don't find us." He tries again to say something, but she glares at him, her hand clenched tight around the watch, and he closes his mouth with a snap. She goes on. "An' what about this human version of you, yeah? If they find us, he's not gonna understand what's going on, is he? You have no idea how he's gonna react, do you? You said the TARDIS will make sure he's got memories of a real life -- whether or not they find us, he's not going to believe he was once an entirely different species--"
"You don't know that!" he interrupts, loudly.
She snorts. "Who's the human here?" Suddenly, her face softens a bit. "You're pretty old, and you've been around humans a lot, but Doctor, you obviously don't understand what it's like to be one of us any more than we understand what it's like to be you."
He finds he has nothing to say to that.
She sighs, and gives him a slight smile before saying, "An' that's the way it should be. You're a Time Lord, Doctor. 'S who you are. Don't ask me to stand by while you take that away, 'cause I can't. I won't. I'm human, and I'm fine with that, but it's not right for you."
She steps forward and takes his hand, placing the watch in it and curling his fingers around it. She takes his other hand, and he holds it tightly, gratefully. He's amazed anew at how utterly lucky he is to have her. He can't recall anyone else who's ever fought for him like this, and in so many other different ways.
"Well," he says, slightly teasing now, "since you seem to have all the answers, what about the Family?"
Now she gives him a real smile, one of his favorites, her tongue poking out between her teeth. "If they'll really follow us anywhere...why don't we just go to some deserted planet or moon or something? They want you, so you can be bait and lure them away, and in the meantime, I sabotage their ship so they can't leave. We leave, they stay, and no one gets hurt."
He smiles so widely at her, his wonderful, clever, precious Rose. He feels somewhat sheepish at not having thought of it first, but his pride in her overwhelms nearly everything else. He pulls her closer and wraps his arms around her, murmuring in her ear, "All right, I suppose we could do that instead," and is not entirely surprised at how content he is when she giggles in response and wraps her arms around him too.