[He shakes his head, his expression grim.] Time Lords or not, they're still people, and they come in different flavors. [And he's not missing that reaction. Have a look, Rose. But he doesn't call her on it, not yet. Instead, he presses on.] The Master is a genocidal maniac. And regardless of other targets, you're going to be a huge one, as soon as he realizes how much you mean to the Doctor. You're going to have to be extra careful.

[Because if anything happened the Rose, who knows what the Doctor would do. Or what Jack himself would do. Except that, no, Jack knows exactly what he would, what he's wanted to do to the Master for far too long. If the Master harms one hair on Rose's head, Jack will kill him in cold blood, the Doctor's reservations about the other Time Lord be damned.]