The Lodger - S5-E11
Continuity mistake: When the Doctor is flipping through a book while talking with Amy on his earpiece, in the close-up shot he's using his right hand, but in the wide shot is using his left hand, going through the pages the other way. (00:12:10)
Chosen answer: The Master knows that deep down, he deserves death for the crimes that he's committed throughout his life, and since he regards The Doctor as his arch-foe, he expects it to be at his hands. The fact that The Doctor is still willing to forgive him for all of his crimes hurts him more deeply than death would.
Captain Defenestrator