[Through the threat of torturing Sarah and Harry, Davros has managed to coerce the Doctor into explaining the reasons why the Daleks get defeated in various future battles. Satisfied with this, Davros now wants to have a more civil conversation with the Doctor, alone, "not as prisoner and captor, but as men of science"
Now, future errors will be eradicated. Defeats will become victories. You have changed the future of the universe, Doctor.
I have betrayed the future. Davros, for the last time, ...