Lincoln in the Bardo by George Saunders:
Of course, there was always a moment, just as an order was given, when a small, resistant voice would make itself known in the back of my mind. Then the necessary job was to ignore that voice. It was not a defiant or angry voice, particularly, just that little human voice, saying, you know: I wish to do what I wish to do, and not what you are telling me to do.
And I must say, that voice was never quite silenced.
Although it did grow rather quiet over the years.