Wilf looks at him, the hollow fear of him, and holds it out again. He'll deny you three times, that's how this works. Wilf's canny. "If the Master dies, what happens to all the people?" The Doctor pauses too long, before he lies that he doesn't know. "Doctor, what happens?" The template snaps, and everybody lives, and everybody goes back to normal. "Then don't you dare, sir. Don't you dare put him before them."
That's what he says, but not what he means. What he means is we're in dead man's alley, in the Age of Steel, and in that world you can't stay clean. You can try, you can hold to your ideals until the rats eat your bones. What he means is that the Doctor can't put himself, his godlike innocence, above them all. Can't save Ianto when it means a crimson tithe. Can't shove that hardness off into Pete's World, like Ten Five, for being too ugly. Can't afford to stay above the fray, soft and uninvolved. You can't put those ideals before the innocent, without losing them altogether.
When I was a child I wanted to learn to play the guitar, just like my father. Until I learned what it would do to my fingers.
"Now you take this. That's an order, Doctor. Take the gun. You take the gun and save your life! And please don't die," Wilf says, beginning to weep. "You're the most wonderful man, and I don't want you to die."
Wilf weeps. He reaches out for the Doctor's hand, placing it over his own. The Doctor looks into his eyes and, crying, swears he can't. That there are limits to how much we can change, no matter what the world does twisting around us.
"A star fell from the sky."
"Don't you want to know where from?" the Master asks, broadcasting on every channel. "Because now it makes sense, Doctor. The whole of my life. My destiny. The star was a diamond. And the diamond is a Whitepoint star." The Doctor shakes beside old Wilf. "And I have worked all night, to sanctify that gift. Now the star is mine, I can increase the signal and use it as a lifeline. Do you get it now? Do you see? Keep watching, Doctor. This should be... Spectacular. Over and out."
The Doctor's fear becomes anger; he can barely explain to Wilf what the Master means. "It's the Time Lords. The Time Lords are returning." Wilf honestly thinks that's a good thing; nobody but the Doctor knows what they became. The Doctor picks up the gun, terrified at himself, getting dirty, and runs.