What an extraordinarily unreasonable response to a perfectly reasonable question. He'd only meant to caution her against giving up caring about this universe prematurely, as she still currently resides in it. She had seemed in need of reminding. Anything he can do afterwards he can just as easily do now. And does she think he ceases to exist when she's not looking? Does she think he'd allow anyone to think that. Where's a pond when you urgently require one. He lets her circle and advance, too confused and pre-outraged to be wary, gaping like a fish before the full extent of what she's said can land.

"Shut up." She's making it impossible for him to talk sense, how dare she go off on these accusatory, belittling tangents. For a moment he's at a profound loss for how to respond beyond that. He wants to slap her, lash at her, but experience doesn't bear that out as any aid to understanding him, unfortunately. "You may very well need my 'tantrums,' if going home is what you want," he says, quite sourly. "Aren't you the obvious choice, for breaking out of an imprisoning universe? The most destructive potential here, besides me. You could be so much more use than you are. Isn't that what you want? One Time Lord machine to another."