Doctor Who (2005) S12 E10
nikkimckelvy -2 points 4 years ago. (Contains Spoilers)

I don’t understand. The Master has regenerated more than the Doctor. This doesn’t even come close to explaining the regeneration incongruence. How can the Master regenerate more than 15 times? Is s/he/it from the same planet at the Doctor? This was an attempt to solve a loose end, and it just created a million more. We need something more comprehensive that falls within cannon, not something wholly outside of it.

Lyrad8791 -2 points 4 years ago. (Contains Spoilers)

I can’t say anything about the regeneration cycles but, I can say that the Master and Doctor were childhood friends. I believe that has been pointed to in multiple episodes across the series thus far. Personally, I am not watching anything written or directed in the current setup, so don’t know what has been changed.