The Doctor is buried in his work, a pile of cables and wires at his feet. For that reason, he doesn’t even address the Master when he arrives. Not until, that is, he steps in front of him and disrupts his work.
“Somethin’ I can help you with?” he asks a bit stiffly. He hadn’t felt much like sleeping lately. There wasn’t much point when the other side of the bed was so often empty.
“I know you’re cross with me. But I missed you and I wanted to hold you for a while.”
I just want every Doctor that follows me to know that the Master embodies Missy’s statement that no matter the face, every incarnation of the Doctor is THEIR Doctor. Every single Doctor is beloved of the Master, bitterly wounded by their abandonment, chasing them across the cosmos, begging them with each horribly misguided “command” to look at the Master again, and remember their best friend.
The Master will pursue every Doctor until time and space cease to be.