Doctor Who season 11 is rewriting the history of the Doctor, revealing a secret side to the Time Lord's life that has never been shown before. New showrunner Chris Chibnall seems to be taking a bold new approach; not only is the Doctor finally a female, but this incarnation is opening up about a past that's only ever been hinted at.

That, though, is the magic of Doctor Who. This is a show that completely reinvents itself every few years; every time the Doctor regenerates, it's an opportunity to take the series in a whole new direction. When a regeneration comes at the same time as a new showrunner, the transformation is even more distinct. Jodie Whittaker herself stands as a symbol of that, the first female Doctor who's already proved herself in just a handful of episodes.

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But what new elements is the latest season adding to Doctor Who? How will they change the shape of the BBC's longest-running science-fiction TV series for years to come? Here, we're going to explore some of the key changes Chris Chibnall seems to be making to the Doctor's past.

The Doctor Was Female Before Jodie Whittaker

Jodie Whittaker as The Thirteenth Doctor in Doctor Who

Doctor Who season 11 episode 4 "Arachnids in the UK" saw the Doctor and her friends return to Earth, and gave the socially awkward Time Lord a chance to make small talk. Suffice to say, it didn't go well; her meandering comments included a reference to space assassins, leaving Yaz's family bewildered and confused. But one single line of dialogue stood out; the Doctor's aimless chatter drifted to reminiscing about a time when she was "a sister in an aqua hospital." A "sister," of course, is a female nurse; taken at face value, this seems to suggest that there have been previous female incarnations of the Doctor. It fits well with a single line of dialogue from season 10, when Peter Capaldi's 12th Doctor recalled back to his Academy days. "I think [the Master] was a man back then," he said. "I'm fairly sure that I was, too. It was a long time ago, though."

Given the Doctor came to the end of his/her regeneration cycle in the Matt Smith era, needing a fresh injection of regeneration energy from the Time Lords, this seems to cause something of a problem to continuity. Either the Doctor was just rambling, talking utter nonsense, or else the Time Lords had given the Doctor a fresh regeneration cycle once before. If that's the case, there are 13 past Doctors who've never been seen on the TV, and who predate William Hartnell's classic incarnation. What's more, at least one of them was female.

Related: Doctor Who: Each Doctor's Best Episode

There are a couple of subtle hints in the old series that support this idea. "The Brain of Morbius" included a scene in which the Doctor engaged another Time Lord in a psychic battle; faces of his previous incarnations flashed on the screen, running back through Jon Pertwee, Patrick Troughton, William Hartnell - and then on, to eight other faces. It clearly implied that Hartnell's wasn't the First Doctor, after all. Meanwhile, in the Sylvester McCoy era, the Time Lord reminisced about the ancient days of Gallifrey - times surely too far in his homeworld's past for even the Doctor to remember.

Page 2 of 2: The Doctor Had Sisters... And A Family

Doctor Who Arachnids In The UK

The Doctor Had Sisters

The same scene from "Arachnids in the UK" saw the Doctor drop another bombshell on viewers: "I used to have sisters," she rambled. There have been previous canon references to the Doctor's parents, children, and even grandchildren, but this is the first time there's ever been a reference to the idea the Doctor had sisters.

The BBC recently published a canon novel bearing the title "A Brief History of Time Lords." Written from the perspective of a disillusioned Time Lord, it revealed that the vast majority of Gallifrey's inhabitants live outside the famous bubbled cities, and explained just how a person becomes a Time Lord. It involves leaving your family behind.

"Almost the whole population lives outside the cities. Billions of native Gallifreyans in their farms and homesteads, working through the day to feed themselves - and us - until the night-time comes... The thing that every 7-year-old on Gallifrey truly dreads is turning 8. Being taken from their family and failing the selection. What will you fail to become, child? Soldier? Chancellery Guard? Time Lord?

"Or, worse, will you pass, and spend all your lifetimes inside one of those bubbles? Forget your past life, until it comes naturally for you to recoil from the outside, shut it out, forget it? Perhaps you'll only cope with your sterile existence by shutting out all that life. Or by shutting yourself in."

The Doctor, it seems, passed the selection process and became a Time Lord. Did her sisters? Or did this early incarnation of the Doctor abandon them, forget about them, focus on his or her new life at the Time Lord Academy?

At this stage, it's impossible to say for certain. All that can be confirmed is that the Doctor had sisters - and, significantly, she believes they're dead. "I used to have sisters," the Doctor observed, and it's unclear how far back she was remembering at that moment. It's believed that only Time Lords have the ability to regenerate, not all Gallifreyans. If the Doctor's sisters failed the selection process, then they may have died millennia ago - perhaps more, if the Doctor really has had multiple regeneration cycles in the past.

The Doctor Had A Family

Doctor Who And Family

"Family" seems to be the central theme of Doctor Who season 11, so it's perhaps no surprise that Whittaker's 13th Doctor has spent more time reflecting on her family than any other incarnation to date. In the first episode, "The Woman Who Fell To Earth," the Doctor attempted to comfort her friends by talking about how her family are always with her. "They may be dead to the world, but they're not dead to me," she declared. It's a strange inversion of a speech given by Patrick Troughton's Second Doctor in "The Tomb of the Cybermen." There, he told a grieving companion that he had lost his family many years ago, that he could choose to remember them but that the passing of time had healed the wounds.

"I have to really want to [remember them], to bring them back in front of my eyes. The rest of the time they sleep in my mind, and I forget. And so will you. Oh yes, you will. You'll find there's so much else to think about."

Whittaker's Doctor is more empathetic and able to understand the feelings of others. As a result, she seems to recognize the value of family a lot more. She doesn't want to forget the people she's loved and lost, but rather she chooses every day to remember them and carry them in her heart. It marks her as a very different incarnation of the Doctor - but it also means viewers are getting new insight into the Time Lord's backstory.

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While these themes and ideas are subtle, they've been carefully threaded through almost every episode so far. It looks as though they're building to a head, suggesting that perhaps the Doctor's family aren't quite as dead and buried as she believes. If that's the case, could one of the Doctor's siblings even be the "Timeless Child" alluded to in "The Ghost Monument?" Right now, only one thing is certain: this trend looks set to continue, meaning the Doctor's past - and even her family ties - are likely to be further fleshed out as Doctor Who season 11 continues.

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