The return of Ace in Jodie Whittaker’s final Doctor Who adventure may create a canon issue for the show. Ace was last seen walking back to the TARDIS with the Seventh Doctor at the end of “Survival”, the final serial of the show’s original run, in 1989. However, the character has had a full fictional life over the ensuing three decades, creating some potentially complex issues.
Across audio dramas, comic strips, spin-off series, and novels Ace has died, left the Doctor, trained as a Time Lord, and set up a charitable foundation. It remains to be seen just what role Ace will have in the upcoming special, given her confusing timeline in spin-off media. To confuse matters further, the actor that plays her, Sophie Aldred, co-wrote a novel At Childhood’s End, published in 2020, which had Dorothy “Ace” McShane meet the Thirteenth Doctor, Yaz, Ryan, and Graham.
In the trailer that followed “Legend of the Sea Devils”, Ace says that it’s been over three decades since she last saw the Doctor. Which, given the timey-wimey nature of the Doctor and their companions’ lives could still be true regardless of where or when their journey ended. However, this statement contradicts the events of Aldred’s novel At Childhood’s End in which the Thirteenth Doctor and Ace reconcile their differences after their difficult parting decades prior. Ace’s return to the series in the upcoming special causes a canon headache because it looks like it will ignore the events of the novel, potentially undercutting previous events.
Chris Chibnall’s decision to ignore the events of At Childhood’s End does make sense, however. Ace is a much-loved companion to many, so it’s unlikely that the TV series would want to point viewers in the direction of a novel over playing out their reunion on-screen. The novel also features some strong scenes between The Doctor, Yaz and Ace that are reminiscent of the jealousy experienced by Rose Tyler when she meets Sarah Jane Smith. Consigning those to a novel rather than depicting them on-screen would also be a disappointment for viewers.
However, all of this ignores the fundamental fact that Doctor Who is a show about time travel. In the previous series, the Grand Serpent completely rewrote the history of the series’ military task force UNIT. It’s easy enough for both the events of At Childhood’s End and this final Jodie Whittaker episode to exist in divergent timelines. Indeed, in the novel, Ace experiences multiple alternate timelines of her experiences with the Doctor that encompass her comic strip, novel, and audio adventures. Most canon issues in Doctor Who can be explained away in a similar way, time is always in flux and the Doctor rarely travels in a straight line. As a result, the show’s canon can be constantly rewritten and reshaped.
It's also unclear as to whether Ace will meet the Doctor in the next episode. The only footage released so far is of her attacking a Dalek with a baseball bat and firing a machine gun at an advancing foe. Perhaps they’re helping out on the periphery of the Doctor's final battle with the Master. If that were the case, then Chris Chibnall could neatly side-step any issues with the existing Doctor Who canon. Whatever happens, viewers can all agree that the prospect of the Seventh Doctor’s companion Ace returning to the series is very exciting indeed.