You have a point. She DID bring them together after all. And Missy was always enouraging him to join the Darkside (with herself, obviously, being the cookie) - but he outMastered the Master. He always knows when to stop. Missy is mad, but I'm not sure she was aiming....

Nevermind. Messing with Rassilon and Gallifrey? She'd be down with that. The Doctor would be the only one who could accomplish that and her hate of her home planet is worse than his (considering what they did to her).

So...you got me here, lol!!