Board Thread:The Panopticon/@comment-4028641-20151008023030/@comment-38288735-20200103133711

I agree that we shouldn't do anything concerning our newest Master until after the Spyfall story actually ends. However, if Part 2 gives no substantial indication whether he is post-Missy or is a previous regeneration to her, I believe we should proceed as if he is the latest incarnation until other evidence shows otherwise (if it ever does).

Unlike the EU, the TV show does not have a strong history of having characters meet out of order, River Song (and, by their nature, multi-Doctor or Master stories) being the only major exception. There are very few cases where TV episodes take place out-of-order for any characters. Just because we have evidence that it's possible he came before Missy, doesn't, to me, justify ignoring the TV show's long history of keeping things in-order.

All that being said, unless the plot keeps the Doctor and the Master from having a decent-length conversation in Part 2, I feel like it would be very poor writing to not have the Doctor address the change-in-personality from the redeemed Missy, so this is all probably very academic.