The secret’s out – John Simm’s Master is back for Doctor Who Series 10. As a firm fan-favorite and one of Nu-Who’s best villains, this is a pretty massive deal in a season that already boasts Mondasian Cybermen, Ice Warriors, and a regeneration. Although, like any great return in the canonically-challenged time-travel series, it does pose a string of massive, confusing questions.

Doctor Who has a history of bringing back iconic baddies regardless of how little it makes sense (the Daleks have been completely wiped out three times since 2005 only to return after a matter of episodes), but the logistics for Simm’s return are particularly convoluted. Not only was his iteration presumed dead after the end of David Tennant’s run in 2010, but the character has since been seen menacing/flirting Peter Capaldi’s Doctor as Michelle Gomez’s gender-swapped Missy.

From what little details have been revealed of the actor’s appearance, it’ll be achieved through simple time travel (rather than any clones, replicants, doubles, dreams, un-regeneration or other classic Who deception) and see Gomez and Simm share the screen in a dark, twisted version of 50th Anniversary team-up “The Day of the Doctor” (which had David Tennant and Matt Smith working together). But while that’s hand-wavy enough for BBC execs, in the scope of the mythology it’s just the tip of the space-berg. Here’s how we think it will happen.

The Master’s Timeline: Explained

The Master Doctor Who BBC1 Doctor Who: How Can John Simms Master Return in Season 10?

Forgoing the Classic era (because we’d be here all day and the rebooted series has played rather free-and-loose with it anyway), The Master’s timeline is actually rather tight in Nu-Who. He disappeared during the Time War, presumed dead, but actually escaped the conflict using a chameleon circuit that made him human (in the form of Derek Jacobi, no less). As an old man he finally opened his lifelong-held fob watch, unleashing his Time Lord form and (after being shot) regenerated into Simm.

Simm tried to take over Earth using mutated future humans, but the Doctor stopped the paradox and his “wife” “killed” him. He returned a few years later after being resurrected by said wife (it was a bit silly) where he tried to save Gallifrey from the Time War, only to discover how corrupted the Time Lords had become and eventually worked with the Doctor to stop them, sacrificing himself and finally locking himself in the conflict in the process. The character was then missing for all of Matt Smith’s tenure, eventually returning as Missy, an incarnation that really plays up her and Doctor’s strange relationship.

Despite a recurring role in Series 8 and 9, we’ve not actually learned much about where Missy came from, leaving a massive gap between Tennant’s swansong “The End of Time” and the first allusion of Missy in “The Bells of Saint John” where what happened to The Master isn’t clear. Because we’ve followed Simm’s character pretty much from his regeneration through to getting trapped in the Time War, his new appearance must come in this gap.

This fits what we’ve come to expect of current Who. Showrunner Steven Moffat is a big fan of addressing seismic continuity questions through his seemingly disconnected narratives – “The Day of the Doctor” cleared up a myriad of confusion about the connection between the old and new series, while “The Time of the Doctor” wrapped up pretty much every dropped Matt Smith thread and the pesky regeneration limit. As such, it’s logical to expect that bringing back Simm is a way for him to explain Missy’s unfound backstory before leaving at the end of the season.

What Happened To Simm’s Master?

John Simm as the Master in Doctor Who The End of Time Doctor Who: How Can John Simms Master Return in Season 10?

So, what’s going on with Simm? Well, because Missy has played so coy with the Doctor about her origins, there’s not much to go on. The most specific piece of backstory is her pre-reveal statement that she was “The one you left to die”. This line contrasts with previous Master “deaths” – the first time Tennant begged Simm to regenerate (he refused) and the second Simm made a pointed noble sacrifice – so could be a reference to a future event where the Doctor forsakes the Master; a time loop where Missy’s anger with the Doctor comes from an event he’s yet to experience and she may have in fact influenced.

Of course, that’s just a single line of dialogue and it may have been used because, hey, it sounds cool. We’ve got something much bigger to factor in: Gallifrey. When Doctor Who was brought back, writer Russell T. Davis chose to write out all other Time Lords by having them and their home planet destroyed (he eventually went back on that briefly with “The End of Time” before having it time-locked away again). When Moffat took over, though, he slowly but surely reintroduced the planet: “The Day of the Doctor” dealt with its final days and the Tom Baker cameo revealed it had actually been moved to a new pocket of space, with the Doctor finally returning to his post-war home at the end of Series 9.

It’s possible this change is what freed The Master. It could even be that the being “left to die” Missy refers to is the Doctor saving Gallifrey but not finding his one-time ally. However, because Missy was active before the planet was saved (she helped Clara find the Doctor in Series 7 off-screen) and already gave false directions to the risen Gallifrey before, something more complex appears to be at play; although due to the show’s time travel logic being so fluid it’s hard to be too sure.

What we can say with some degree of certainty is that all of this will be linked. Moffat likes to construct massive continuity problems then meticulously correct them with the fervor of fan fiction. We’ll most likely see Simm freed from the Time War and coming across Capaldi and his future self, wreaking havoc in one last hurrah.

In that vein, one very interesting sub-question is how the two versions will interact. One of the biggest rules of the Doctor meeting past versions of himself is that only the furthest ahead in his timestream remembers the encounter (otherwise he’d immediately know the solution and there’d be no tension). How strictly this is observed varies from story to story, but it has become more widely accepted in recent years. This means when Missy meets The Master she won’t remember having done so, possibly leading to direct conflict (and definite confusion given the gender swap) before they (inevitably) work together.

Conclusion

John Simm as The Master in Doctor Who Doctor Who: How Can John Simms Master Return in Season 10?

Fitting of his seven years as showrunner, it looks like Steven Moffat’s decision to bring back John Simm is part of his ongoing efforts to smooth out Doctor Who’s ever-contradictory continuity. He himself made a gap in The Master’s timeline that belied accepted logic and now he’s going to plug it, likely using the return of Gallifrey that he’s executed with previous canon shake-ups. This will result in Masters 6 and 7 meeting and in the process probably show the former’s regeneration into the latter. This depth of focus on The Master is unprecidented in the show’s history; like child Davros last season it’s going more intimate with a villain than we’ve ever seen before.

We may be about to undergo a massive restructuring of Who, with a new showrunner and lead pushing forward a top-down reboot, but it certainly looks like Series 10 won’t end the Moffat/Capaldi-era quietly.

Next: How Doctor Who Failed Peter Capaldi

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