The Doctor fixes the Master with one of those looks. Maybe it's this regeneration or maybe it's trying to reconcile the fact that this isn't the same Master out there in the wasteland, but he's actually unsure how to read him. After all these centuries, all those lives. And now he can't tell if he's being sarcastic or showing genuine regret. The Doctor tilts his head as the other Time Lord slumps back, studying him like he would his companions.
The difference, however, is that the Master's anything but. He's dangerous. Even on his best behavior, the Doctor reminds himself that he's not some human he can amaze with a short hop to the Moon.
"Ah, my mistake," the Doctor says quietly. He laces and unlaces his fingers together in his lap, as if looking for something to do with his hands. He doesn't say anything for a moment, until it occurs him to ask. "Do you still hear them, by the way?"
He doesn't think he needs to specify what "them" is.
Could be something! I didn't think of it until now
The difference, however, is that the Master's anything but. He's dangerous. Even on his best behavior, the Doctor reminds himself that he's not some human he can amaze with a short hop to the Moon.
"Ah, my mistake," the Doctor says quietly. He laces and unlaces his fingers together in his lap, as if looking for something to do with his hands. He doesn't say anything for a moment, until it occurs him to ask. "Do you still hear them, by the way?"
He doesn't think he needs to specify what "them" is.