Doctor Who: Why did 13 regenerate into 10?

Jodie Whittaker’s 13th Doctor Who regenerating into David Tennant’s 10th Doctor Who is a mystery that is yet to be solved, allowing for conspiracy theories from fans.

Doctor Who recently aired its special episode titled “The Power of the Doctor”. The special was part of BBC’s centenary celebrations and it promised to be filled with surprising twists and turns. But it was the final events of the episode that left many with their jaws on the floor.

This is as Jodie Whittaker, the 13th Doctor surprisingly regenerated as David Tennant’s 10th Doctor.

This cliffhanger has not been explained intentionally, as Tennant will return for three episodes in the sixtieth anniversary celebration episodes, which has allowed fans to speculate until fall 2023.

David Tennant’s return to Doctor Who was confirmed ahead of 13th’s regeneration

Jodie Whittaker’s 13th Doctor regenerating into David Tennant’s 10th Doctor was an unexpected surprise. This is as Sex Education’s Ncuti Gatwa was already confirmed as the next Doctor Who.

Tennant’s return to the hit sci-fi series was already confirmed prior to the special episode, but before he returned, fans were interested to know how he would return to the series.

This opened a can of worms as fans struggled to understand why Whittaker’s Doctor regenerated back instead of into the new and confirmed 14th Doctor Who played by Gatwa.

Doctor Who: Why did 13 regenerate into 10?

Doctor Who’s special episode “The Power of the Doctor” was released as part of the BBC’s centenary celebrations, but it was long confirmed that it would also mark the end of Jodie Whittaker as Doctor Who, after she played the character since 2017, becoming the first female actress to play the character.

After an epic journey throughout the feature-length special episode, which saw some old familiar faces return, The Master was found to be the culprit of the events from the episode as they wanted to create a forced regeneration device.

Doctor Who is able to regenerate into the Master by force, and by the end of the episode, the Doctor creates a hologram projection. With Yaz’s help, they are able to regenerate the body back into the 13th doctor.

However, recognising that they have been weakened, they decide to regenerate by leaving the confines of the TARDIS to “take in one last sunrise” by materialising on a clifftop.

Whittaker’s Doctor ends her run by stating, “Right then, Doctor whoever I’m about to be – tag, you’re it!”

Only for her to regenerate into David Tennant’s 10th doctor as the 14th, who delivers his debut line about now recognising his teeth before sharing his signature line, “what”, several times.

Since the series has intentionally left the matter in the air, there have been some touted conspiracy theories regarding the matter, especially after the upcoming season’s trailer confirmed that Ncuti Gatwa will now be the 15th Doctor, and not the 14th.

Where to buy Doctor Who: Origin Stories

Theory 1: The Master’s forced regeneration device is to blame

One of the most supported conspiracy theories is that the reason that the regeneration went wrong is the Master’s forced regeneration device.

In Jodie Whittaker’s Doctor creating the AI Hologram to defeat him, it is believed that when it was time to regenerate, the events that led up to the moment affected her regeneration, hence, it regenerated into an old form because of a glitch.

The trailer already indicated that Ncuti Gatwa’s 15th Doctor is also aware that there was a glitch in the regeneration, as he was meant to be the 14th Doctor Who.

Theory 2: Donna is the link

While it was confirmed that David Tennant would return for the sixtieth anniversary of Doctor Who in November 2023, the special episode revealed how.

Moreover, the release of the trailer confirmed that his companion, Catherine Tate, would return to reprise her role as Donna Noble, which has led many to believe that because of the glitch, Tennant’s Doctor returned because Donna still has half of his mind after the meta crisis took place in his seasons as the Doctor.

Hence, he is back to reclaim his mind in order to ensure that the regeneration takes place successfully this time.

Theory 3: The series was inspired by the comic strip

Another theory is that in light of the series’ upcoming sixtieth anniversary, the writers are revisiting the source material for inspiration as a regeneration-gone-wrong has already happened in the comic strip.

In 1979’s Doctor Who Weekly, two issues featured the reversion of Doctor Who as the events in the comic strip show time moving backwards.

As such, k-9 turned into a pile of components, which forced the doctor to reincarnate into his previous forms rather than to regenerate. It featured Jon Pertwee and William Hartnell’s Doctors and stopped with William Hartnell’s Doctor.