Doctor Who’s big twist betrayed the show’s oldest rule

Doctor Who has to learn to let go of David Tennant.

In its most recent episode, Doctor Who broke one of its oldest and most fundamental rules. On the one hand, it can be exciting when a long-running pop culture property breaks a rule it has set for itself; it means something interesting is about to happen. On the other hand, sometimes breaking a rule is boring and self-indulgent. I’m afraid that in Doctor Who’s case, we’re following the second scenario.

Spoilers for Doctor Who follow.

Here’s the trick that made Doctor Who run for 60 years since its first premiere in 1963 (plus or minus a decades-long hiatus and an ill-advised TV movie): The Doctor always changes.

Doctor Who is an institution of science fiction, but it has a deceptively simple premise. The titular Doctor is a member of an alien race known as the Time Lords. He has a time machine/spaceship called the Tardis. He likes to pick up a friend periodically — usually a human from the late 20th or early 21st century, frequently a young woman — and travel with them through time and space, having adventures.

Sometimes the Doctor and his companion go back in time and meet Sir Isaac Newton. Sometimes they go to the edge of the universe and explore a haunted spaceship. They can go anywhere, to any time or any place. And, crucially, the Doctor can be anyone.

Every time the Doctor dies, he regenerates into a new body, played by a new actor. The way he expresses his personality shifts: he goes from crotchety to fun-loving to aggressive to cold. He picks up a new signature outfit, a new signature catchphrase. He loses old companions and gains new ones. He redecorates the Tardis.

Yet the Doctor remains the same character with the same history. He always changes; he is always the same. This paradox is the heart of the show, and it’s why Doctor Who has managed not just to last so long but to also turn out good episodes on a fairly regular basis.

The premise of regeneration is flexible. It is practical. It can withstand cast shifts and actor disputes. It prevents stasis and staleness. Most importantly, it speaks to the truth of how identities work: Our personalities are not set; they flux and change and distort themselves in bizarre ways we can never fully understand. We change, we grow, we lose who we used to be.

All of which is why the Doctor’s most recent regeneration, which aired December 9, is so frustrating. Doctor Who broke its own rules. For the first time, the Doctor kept his past self.

The newest episode was the third and final of a mini-season’s worth of specials airing between seasons 14 and 15. The specials were highly anticipated, in part because they were all written by Russell T. Davies, who first resurrected Doctor Who from the dead in 2005 and departed in 2010. (The original run of the show aired on the BBC from 1963 to 1989.) The specials also starred David Tennant, whose iconic turn as the Tenth Doctor made a new generation of fans fall in love with Doctor Who. The whole thing was a fairly straightforward plea for old fans to come back after a few seasons of falling ratings.

Tennant’s return to the role was teased in October 2022 when Jodie Whittaker’s Thirteenth Doctor died. (Whittaker was the first woman to take on the role.) Officially, the Thirteenth Doctor was supposed to regenerate into a Fourteenth Doctor played by Ncuti Gatwa, the first Black actor to play the Doctor. Instead, in a surprise twist, Whittaker transformed into Tennant, now taking on the role of the Fourteenth Doctor.

“If you thought the appearance of David Tennant was a shock, we’ve got plenty more surprises on the way! The path to Ncuti’s Fifteenth Doctor is laden with mystery, horror, robots, puppets, danger and fun!” teased Davies in a statement shortly after the episode aired. “We’re giving you a year to speculate, and then all hell lets loose!”

The official plan was that Tennant would play the Fourteenth Doctor through the three 2023 specials and that, at the end, Tennant’s Fourteenth Doctor would transform into Gatwa’s Fifteenth Doctor. In the most recent episode, “The Giggle,” that’s not quite what happens.

Instead, when the Doctor regenerates, he splits into two people. One is played by Tennant. The other is played by Gatwa. Both, they assure everyone at once, are equally the Doctor. Fourteen and Fifteen are both alive together, at once.

Each of them even gets their own Tardis, the Doctor’s trademark spaceship/time machine. The pair agree that Gatwa’s Doctor will go off and have adventures, which presumably the show will go on to follow. Tennant’s Doctor, meanwhile, will rest with his old companion Donna Noble and heal from his PTSD — and, presumably, remain available for guest appearances whenever ratings are in danger of flagging.

“David [Tennant] is parked,” Davies explained in the companion show Doctor Who Unleashed. “For once, we’ve got a happy Doctor who is no longer saving the universe, but is parked with Donna (Catherine Tate) for a happy life, while the Doctor — which is always the next Doctor, and that’s always true of Doctor Who, the Doctor is the next Doctor — is out amongst the stars.”

The transition is a remarkable echo of the last time David Tennant’s Tenth Doctor regenerated, back in 2010. Back then, Tennant had a handy clone available who went off to live with his old companion Rose Tyler in an alternate universe, while the central Tenth Doctor reluctantly died and transformed into Matt Smith’s Eleventh Doctor. This time, the Fourteenth Doctor doesn’t have to die, or even so much as move to a different dimension. He simply retires to the suburbs.

This persistent desire to hang on to Tennant shows Doctor Who (and particularly Davies’s Doctor Who) talking out of both sides of its mouth. It’s as if the show is saying, “Yes, yes, on the one hand the Doctor always changes, but on the other hand he is also always David Tennant and he is also always living somewhere safely with your favorite companion, unless you are a Martha fan lmao.” Tennant gets treated as though he is somehow more the Doctor than any other incarnation.

On the official Doctor Who podcast, Davies teased the idea that the bigeneration of Fourteen and Fifteen may have caused the whole timeline to bigenerate, so that each past Doctor now is alive in a splinter timeline. “I think all of the Doctors came back to life with their individual Tardises … and they’re all out there traveling round in what I’m calling a Doctor verse,” Davies explained.

The attempt at a Marvel-style endlessly overlapping universe line is self-indulgent and sentimental in all the wrong ways. It is a betrayal of what makes regeneration such a durable and dramatically rich premise, which is that the Doctor can never fully regain his past self — and neither can the audience. Even if you are a Time Lord, the past is a foreign country, and your own personal past especially so. We can never fully go back — until the BBC decides it’s time it got its own MCU. In that case, we go back again and again.