The Doctor vs the Master was a short story published in September 2020 in Doctor Who The Official Annual 2021. It was subtitled The Best of Enemies and posited one more interview, through the psychic link between the Thirteenth Doctor and the Spy Master during the events of TV: Spyfall.
With the Thirteenth Doctor and the Spy Master locked in their ill-advised psychic link, the two friends-turned-enemies are forced to talk through their issues. Although the Master taunts her about some of what she believes about herself being a lie, he quickly decides to make the conversation about him, and the two go over their complicated history, from two young Time Lords staring into the Untempered Schism to the relaxation of Missy's relationship with "her" Doctor, which the Master now claims to regret. When the Doctor tries to get back to the mystery he is holding out of her reach, he simply taunts her some more and leaves the conversation.
- The Thirteenth Doctor recalls that the Master who opposed her in her third incarnation was "an old charmer".
- She notes that Missy was every bit as dangerous as her other incarnations, despite her "Mary Poppins looks".
- She believes that the Master's stint as "a decayed monster" was caused by him "trying to regenerate one time too many".
- This story suggests that the Decayed Master played by Peter Pratt was not the mouldering remains of the thirteenth incarnation of the Master's first regeneration cycle, as most other stories suggest, but instead the egregious result of the Master's attempting to regenerate beyond the twelve-regenerations limit of their original cycle. This idea had first been proposed by PROSE: Meet Missy!.
- The story was also notable for confirming outright that Sacha Dhawan's Spy Master was a later incarnation from Missy via having him remember having been her — although this had become the prevalent interpretation by then and been confirmed behind-the-scenes by comments from Chris Chibnall[source needed].
- The Thirteenth Doctor and the Spy Master are engaged in a psychic link. (TV: Spyfall)
- He repeats his warning to her that "everything [she] thinks [she] knows is a lie", (TV: Spyfall) but says he will only explain what he means "once [he's] good and ready". (TV: The Timeless Children)
- The Master tells the Doctor how the Untempered Schism inspired him. (TV: The Sound of Drums)
- The Doctor recalls how the Master once "stole someone's body" to "get back in business" after his time spent as a "pitiful half-dead thing". (TV: The Keeper of Traken)
- The Master reminds the Doctor of her exile, (TV: The War Games) execution, (COMIC: The Night Walkers) and life working for UNIT in her third incarnation. (TV: Spearhead from Space)
- The Doctor says the next time she met the Master after he was "Harold Saxon", he was Missy. (TV: Death in Heaven) The Spy Master acknowledges having been her in his past, but looks down on her for "spen[ding] too long in [the Doctor's] company" and trying to better herself. (TV: The Eaters of Light, The Doctor Falls)
- A disappointed Thirteenth Doctor once again looks back wistfully on how Missy seemed to be improving. (COMIC: Old Friends)