Doctor Who returns to the small screen for its tenth season -- and it's going to be a big one. This season sees the addition of a brand-new companion, Bill (Pearl Mackie), and the return of John Simm as the Master, but also sees the end of Peter Capaldi's run as the Doctor, and Steven Moffat's long tenure as showrunner. Of course, few of these changes are entirely unexpected, as the show thrives on a constantly changing cast, with new companions and the Doctor regenerating every few years.

The Doctor's regeneration is, in fact, one of the key things that separates him from humans, and allows him to continue to live and travel through time for decades to come. At any point where the Doctor is critically ill, fatally injured, or dying of old age, he is able to regenerate, creating a new body and personality. At the end of this season, Capaldi's exit will (presumably) involve the rebooted series' fourth regeneration, as he 'dies' and a new Doctor takes his place.

Now, in an interview with the New York Times, Capaldi reveals that his regeneration isn't going to be as straightforward as past ones have been on the show, teasing it's "complicated" nature.

"I know what’s going to happen. It’s more complicated than that. There’s this notion now that it’s the same process he’s gone through every time, and that’s not true. It’s only the last couple of regenerations that have been, as it were, fairly straightforward ones. I can’t go into the details of a lot of it, because I know what happens, but I don’t know how it happens."

The three previous regenerations in the rebooted series have been due to severe injury. The Ninth Doctor (Christopher Eccleston) was being destroyed after absorbing a time vortex when he regenerated. The Tenth Doctor (David Tennant) regenerated after being exposed to a deadly amount of radiation. Finally, the Eleventh Doctor (Matt Smith) regenerated after centuries at war, about to die of old age. These are all "straightforward" in that they have happened to save the Doctor at a moment when he is about to die.

It will be interesting to see what Capaldi means by a "more complicated" regeneration this time around -- especially as he doesn't know exactly how it happens. This suggests that the Doctor will not be regenerating due to imminent death, but that perhaps he makes a conscious decision to regenerate despite being in good health. Alternatively, things may be complicated by the fact that the Eleventh Doctor was not supposed to have any more regenerations left, but was granted regeneration energy by the Time Lords. This could well make it far more complicated for the Doctor to regenerate from now on.

Of course, Capaldi's words give nothing major away, so there is no way to know exactly how this regeneration will be different from previous ones, but with Moffat also promising to "begin the show again," it sounds like everything is going to be different.

Doctor Who returns to BBC America on April 15, 2017.

Next: Doctor Who: Peter Capaldi Was Asked to Stay Past Season 10

Source: New York Times