Doctor Who: 10 Big Talking Points From The Magician's Apprentice
6. Missy Gets The Doctor's Last Will And Testament
Even more interesting was the idea that the Doctor reciprocates Missy's statement. When he faces certain death at the hands of his arch nemesis Davros - Missy certainly seemed put out by that statement - he send his last will and testament not to current companion Clara but Missy, another member of his own race.
Worse still, he doesn't seem surprised by her arrival in 1138AD Essex. Missy might have entrapped humanity in a fiendish plan and been responsible for Danny Pink's death but the Doctor chose not to reveal to Clara that she survived.
It may have been a betrayal but it also shows how deep his relationship with the Master / Missy goes, even with all the bloodshed they have caused.