Since 2005, every few years, the lead character of BBC’s Doctor Who transforms into a new actor, right before everyone’s eyes. With incumbent show runner Steven Moffat set to depart at the end of the next season, most fans assumed current Doctor Peter Capaldi would leave with him. But now comes word from Steven Moffat that he isn’t writing Capaldi’s exit saying: “I have no reason to suppose that I’m writing out a Doctor…” What could it mean? Will Capaldi stay in the role for much longer than excepted?

Traveling through space and time, righting wrongs, dashing about, all while making knowing-cracks about humanity is the shtick of the most immortal of television sci-fi heroes; the pseudo-titular character of Doctor Who. Pseudo titular because his name isn’t “Doctor Who,” but rather “the Doctor,” and then again, in the mythology of the show not even his “real” name because his real name is still a secret.

The Doctor is also something of a pseudo-character, at least in the literary sense. Most of your garden-variety immortals (like Dorian Gray or Dracula) physically look the same throughout the centuries. Otherwise, if you’re Jack Ryan or James Bond, the differences in your appearance come from artistic license, not fantastical cannonical explanations. Unique among all of narrative fiction (expect maybe short stories by Italo Calvino?), the Doctor not only changes his physical appearance, but his personality alters with each incarnation, too. What began as an off-the-cuff explanation for switching actors back in 1966 has turned into a long-running physiological and psychological conversation among fans and scholars. Which Doctor is the most “Doctorish?” Does he repress certain memories? What actually happens to his anatomy?

Matt Smith regenerates into Peter Capaldi in “The Time of the Doctor”
Matt Smith regenerates into Peter Capaldi in "The Time of the Doctor"

Obviously, a lot of this comes down to fans picking their favorites and debating which Doctor is the best. If you’d never watched the show, all of this might sound like some version of Quantum Leap, in which the lead character is switching bodies constantly, but strictly speaking, this feature of the lead character isn’t the focus of the majority of the stories.

Really, regeneration, is just a backdoor to assist the writers in rejuvenating the character and the brand. After all, Doctor Who has other characters on it besides the Doctor, and they often come and go with or without outrageous science fiction explanations.

8th Doctor Paul McGann regenerates into “The War Doctor” in “The Night of the Doctor”
8th Doctor Paul McGann regenerates into "The War Doctor" in "The Night of the Doctor"

Still, starting with the show’s relaunch in 2005, the contemporary era of Doctor Who fandom became immediately very familiar with the Doctor regenerating into a new actor specifically because it happened at the end of the first season. Right at the start of what many older fans would call “new-Who,” Christopher Eccleston’s Doctor became David Tennant.

David Tennant then did three full seasons before Matt Smith became the Doctor in 2010. Matt Smith, in turn, did three seasons, too and then Peter Capaldi stepped into the the TARDIS in late 2013. Bottom-line: the show has been back on the air for barely a decade and there have been four different Doctors. (Five if you count John Hurt’s one-off as the War Doctor in 2013’s “The Day of the Doctor!”) Historically though, all this this is a bit weird.

Willian Hartnell’s original 1963 Doctor lasted four seasons, while his replacement Patrick Troughton only had three. The third Doctor Jon Pertwee was on for five seasons, which lead to the fourth doctor - Tom Baker - staying in the role for SEVEN seasons.

Before David Tennant in 2006, Tom Baker is arguably most people’s idea of what Doctor Who is all about: goofy scarf, goofy smile, saving the world with bad puns and goggly-eyes. Notably, Tom Baker’s era is where Doctor Who initially found the majority of its American fans in the 70’s and 80’s.

It's Tom Baker!  Your favorite 'Doctor Who' actor!
It's Tom Baker!  Your favorite 'Doctor Who' actor!

The point here is this: Doctor Who can have an actor in the role for longer than three seasons. Further, the obsession with seeing the character replaced is something the contemporary audiences have either been over-stimulated with, or spoiled by. Of course, most Doctor Who fans love a good multi-Doctor story, but the show can’t constantly be in state of transition.

But how popular is Peter Capaldi in the role? While a lot of fans (this one included!) love Capaldi’s wry, irascible portrayal of the heroic Time Lord, there’s definitely a sense that the show is less popular with “the kids,” than it was during the hipster-ish Matt Smith era. If David Tennant and Matt Smith where the conventionally young, sexy Doctors, then Peter Capaldi is like Lou Reed. He’s your father’s Doctor Who, if your father was a teenager who watched William Hartnell in 1963. From an artistic standpoint, one could make the argument that Capaldi’s flippant and cranky attitude is more legit interpretation of a centuries old alien than his fun-loving predecessors, but will that keep him in the role for longer than three seasons?

Michelle Gomez as “Missy” with Capaldi and his sunglasses  in season 9
Michelle Gomez as "Missy" with Capaldi and his sunglasses  in season 9

Obviously, the nature of Doctor Who actors leaving is mostly connected to the actors themselves wanting to leave. It’s impossible to imagine a situation where the BBC would fire Capaldi. The ratings last season were definitely down, but Doctor Who is still one of the most popular science fiction properties on the planet.

Capaldi’s venerable acting chops certainly make him a candidate for playing the Doctor for several seasons to come. The question is: will the fans keep watching? Doctor Who endured back in the 60’s because it found a way to change without compromising. But now, maybe that ever-changing nature has created a jumpy, impatient quality in the viewership. Because if everyone knows they can get a brand-new version of Doctor Who at any moment, why would they want to keep this old one?

Ryan Britt is a staff writer for Inverse. He is the author of the essay collection Luke Skywalker Can't Read and Other Geeky Truths (Plume/Penguin Random House 2015). His writing has also appeared in the New York Times, VICE, The Morning News, The Awl, Clarkesworld, BN Sci-Fi/Fantasy, Tor.com, and elsewhere. He lives in New York City.