10 Doctor Who Questions Not Even Fans Know The Answer To

The nature of the Doctor and the Master’s relationship has always been a subject of keen speculation. The most common theory is that they’re siblings, and it’s not an entirely unfounded idea.

As part of a proposed final confrontation between the Third Doctor and original Master Roger Delgado, the production team were toying with the idea of the Master being the Doctor’s brother, and maybe even sacrificing himself for the Doctor’s sake.

However, Delgado’s untimely death meant that this storyline had to be abandoned.

A hint was then dropped in Fifth Doctor story Planet of Fire, with the defeated Master asking the Doctor to “show mercy to your own…” before meeting a sticky end. Though left ambiguous, it’s since been confirmed that producer John Nathan-Turner intended the final word to be “brother”.

When asked whether the Master was his brother in The Sound of Drums, the Tenth Doctor downplayed the idea, telling Martha that she’d been “watching too much TV”.

The idea is further complicated by Missy referring to the Doctor as her “boyfriend” and proceeding to kiss him. Yeah, for that reason alone, it’s probably best the sibling thing is never actually confirmed now.

It does feel like the two have some sort of deeper connection that's never been mentioned or explored, whatever that might be. Who knows, maybe one day they’ll imply that the Master is the Doctor’s father, or their nephew, or their grandma, just to mess with us.