To begin his second season in the titular role of Doctor Who, Peter Capaldi appears out of the mist driving a tank, wearing Ray-Bans and strapped to a knock-off Fender Stratocaster. It’s an anachronism in so many ways, not least of which in that the scene is set in the English village of Essex in the year 1138. But if this is meant to be a 21st century update of the Doctor, it falls short a couple of decades, playing a blues-rock riff before breaking into “Pretty Woman” and introducing the Medieval villagers to the word “Duuuude.”

Doctor Who is not like other TV shows.

Anachronisms are just part of the DNA of the show, as the Doctor lives across space and time, anchored to present-day England only by his traveling companion, who may need to get back from a Viking-era village or the moon or a space-train centuries into the future in time to teach school. Each episode or two-part arc not only takes place in a different time and location, but often shifts into a different genre, from slapstick action-comedy to moving philosophical drama to some of the most memorable horror elements to ever hit the small screen (like the weeping angels, terrifying statutes who only move when you’re not looking at them).

An iconic series during its original run on the BBC from 1963 to 1989, the show began with an educational mission to introduce its family audience to both British history and science, and so often alternated between episodes set in the past and future. When it was revived in 2005 by executive producer Russell T. Davies, Doctor Who episodes remained varied, but with larger arcs following the Ninth and Tenth Doctors as they traveled across the history of the universe. When Stephen Moffat, who’d been writing for the show since 2005, took over as showrunner in 2010, creating with that kind of unpredictability was paramount.

“I tend to mix it up,” Moffat says backstage at a BBC America event in San Diego. “I used to sort of say back in the day, let’s do a funny one then a serious one, do a future one, do an ancient history one and alternate them. And then I started to think that’s a kind of predictable rhythm, isn’t it? And actually it doesn’t matter a damn. The audience aren’t saying that; they’re saying, ‘Give us something good. Just give us something good.’ If you do four scary ones in a row, that’s fine, as long as it’s good. That’s the critical thing. Nothing else really matters. Make it fucking good.”

An encounter with just a small portion of the show’s passionate fan base would indicate that they’re happy with what they’re getting, no matter whether it’s scary, funny, sci-fi or historical. Dinosaurs in space. Ghosts on an underwater base. Robots in Sherwood Forest. And plenty of the shows’ most iconic monsters, like the Daleks and Cybermen. As long as the story is good and the Doctor is traveling through an old, blue police box that’s bigger on the inside, they’ll tune in across the globe. The show can be seen weekly in more than 50 countries on six continents, including most of North and East Africa and the Middle East. In 2013, the 50th anniversary special aired in 94 different nations. That the Doctor has become more than just a British icon isn’t something that Moffat allows himself to think about.

“For the most part, it doesn’t make a blind bit of difference,” he says. “This [fan event] is a tiny sliver of what we do. It’s obviously the time during which we speak. So I always think people must think I spend my life interviewing and on red carpets and on panels. The truth is we live in our Doctor Who bubble and we turn everybody else away and we make the show as secret as we can. And it’s just ours and we don’t think about it like that. You’re just making the show. And as you know on the show, the crises keep coming. It’s the most draining, exhausting thing I’ve ever done. You’re not thinking, ‘And what about the pressure of 77 million people watching this?’ You always want to say, ‘What about the pressure of getting this fucking thing made in 12 days?’ That’s what I’m thinking about.”

One of the things that makes Doctor Who unique is that the main character has been played by a dozen different actors (13 if you count the War Doctor), thanks to the Time Lord’s ability to regenerate when he might have otherwise died. Each regeneration brings a change of appearance—and to some extent personality. When it was time for Matt Smith to give up the keys to the TARDIS in 2013, BBC hosted an extravagant special to reveal his successor. The 12th Doctor would be played by Peter Capaldi, best known then as the foul-mouthed political spin doctor Malcolm Tucker on Armando Ianucci’s The Thick of It. Fans wondered if we were about to get a surly, swearing Doctor, and it did take the new Scottish Doctor a little while to find that special Time Lord joie de vivre. But Moffat contends that the only real differences between Doctors come from the man reading the lines.

“No one ever quite believes me when I say this, but most of the change is the casting,” Moffat says. “The Doctor on paper, to a surprising extent, is the same. You could give the same scene to Matt Smith, David Tennant, Christopher Eccleston, Peter Capaldi and it would come out differently. You would swear it was a different scene. [Take] one of those actors who can own anything, and the moment they’ve done it you think it must have been crafted for them. The truth is, a lot of what the Doctor does is the same.”

I share Moffat’s comments with Capaldi a few days later and ask him if, after the first season, the writers are reacting more specifically to what he brings to the role. “I definitely feel that,” Capaldi says. “It’s difficult to put my finger on exactly what that is, but certainly they all know me personally now, and they’ve seen what I did with the character in the first season, so I feel that there’s more of a construct. It’s also interesting because I never know—it’s wrong to assume that what you’re sending out is what people are receiving. So they have ideas about me that are not what I thought they might be. It’s always good to have other people’s input, because you can get quite caught up in one’s commitment to trying to do the best you can that you sometimes can’t see where you’re messing up a likeness or messing up a complexity. So, I think the writers can view me more successfully than I can view myself.”

They may be similar characters on paper, but the difference between Smith and Capaldi was the biggest change since the relaunch in 2005. Christopher Eccleston embraced the silliness of the show, an athletic Doctor constantly sporting a jokey grin in the direst moments. David Tennant brought the gravitas of a Time Lord who’d lived centuries and cherished every opportunity for connection with a universe full of creatures. Matt Smith, the youngest actor to ever play the Doctor, had a wild-eyed enthusiasm nearly every moment of his almost four-year run. Capaldi’s Doctor suffers no fools.

“He’s older, obviously,” Capaldi says. “I think he’s less interested in being popular. He’s not user-friendly in that sense. He doesn’t care a great deal of what people think about him, other than Clara—he cares what Clara thinks about him. He’s also quite comic, in his own way. And Clara’s the only companion I know who slaps the Doctor to bring him to his senses, which I think is fun. I think he’s a bit more mysterious and a bit more alien, and he has qualities about him—which we see a bit more this season—which are definitely things only Time Lords can do. I always like when we explore some of his more alien gifts, which we’ll see more of this time around. I think there’s something about the way that I play the Doctor that encourages that.”

This season has already seen the Time Lord encounter two of his biggest nemeses in The Master (now “Missy”) and Davros, the creator of the Dalek race. In that first scene on the tank, he’s in the midst of a three-week party, amusing himself with jokes only he’ll understand, because he believes he’s finally about to die at the hands of his arch-enemy. And he’d only have himself to amuse if it wasn’t his attachment to Clara, which seems stronger than with any other Doctor/companion relationship we’ve seen.

“That bond is absolutely unshakeable,” says Jenna Coleman, who plays Clara, “She tried to walk away, but she couldn’t because that bond is too strong between them, and she knows the Doctor through all forms and she loves him, I think. And she doesn’t want to give that up and give him up, in any way. What I love about Clara and the 12th Doctor is that their relationship is actually about what’s unsaid rather than what’s said.”

This season has also given us Vikings on a spaceship in one of Capaldi’s favorite episodes, with guest star Maisie Williams from Game of Thrones. “One of my most fun days was going on set and seeing Jenna in a spaceship, trying to guide a bunch of confused Vikings around the place,” he says. “It was one of those scenes that when I watched it I thought, this could only be Doctor Who. Vikings on a spaceship—real Vikings, not space Vikings—it can only be Doctor Who.”

“[Maisie Williams] was great,” says Moffat. “The contrast between Capaldi—it’s like a great Victorian actor doing a two-hander with a YouTuber. It feels like that dynamic of two total opposite acting styles, and it’s working beautifully.”

Williams, who we may see more of since her character is now immortal, appeared in one of this season’s many two-part stories. We’re halfway through the season, and judging by titles and directors, the six remaining episodes comprise three more two-parters. “The Zygon two-parter [airing this weekend] written by Peter Harness, I think is a cracking good global/urban, which is not a world we’ve gone into before,” he says. “It’s quite a different and edgy tone.”

It’s the ability to do something different each week that Moffat enjoys most, and executing on those varying styles that he’s most proud of. That the show can be funny and thoughtful at the same time or mix subtle relationship moments with campy adventure sets it apart from just about anything else on TV.

“When Richard Curtis wrote “Vincent and the Doctor” about Vincent van Gogh, we genuinely did a really quite serious, intelligent show about what depression is like in an early-evening adventure serial with monsters,” he says. “So, I’m really proud of that. I’m proud of a lot of them. Even if you’re saying let’s make a fairytale or let’s make a kick-ass comedy or let’s make a chase movie. Most of the time I feel as if we get what we were aiming for. But we are aiming for something different every time.”

And even though Coleman has said she’ll be leaving the show after this season, that variety is a big part of why it’ll be difficult. “The show as a concept is totally malleable and that’s unusual for any show from episode to episode,” she says. “For us, there’s never any chance to get bored. Never mind each series, within each episode, you can totally change the show completely. You look at a show like American Horror Story and they change, each series, what the tone is, whereas we can kind of do that every single episode. But the concept I think is just going to carry on and carry on and why not, because time and space is infinite and the places you can visit is totally infinite.”

Capaldi agrees. “I think that it’s one of the few shows that can actually ask the fun questions of existence and at the same time have men in rubber monster suits chasing you up and down corridors. There’s a B-movie quality to it, which I absolutely love, but at the same time it’s very ambitious in terms of the subjects it discusses. The comedy element of it is absolutely vital because that’s one of the biggest surprises and challenges I found in acting the role, was how you had to be so nimble and move from being very comic to being very tragic to being very dramatic often all within a couple of lines of each other. And it’s a harder role to play in that at a very technical level. But it’s great.”

If there was one controversy with the casting of Peter Capaldi as the 12th Doctor, it came from a chorus of voices who thought it was time for the Doctor to be anyone but another white male. The series and its spin-offs have been pretty good about inclusivity and openness, except when it comes to its main character. When I ask Moffat whether this has anything to do with the Doctor’s assumption of a position of authority throughout white-male-dominated English history, he says that’s not even a consideration.

“The Doctor is usually speaking through a prison cell from the moment he arrives,” Moffat says. “So I don’t think it would make any difference. Whoever we cast as the next Doctor will be the kind of person who could do whatever, they could walk into any room, despite the fact that they’re clearly an intruder, despite the fact that they’re clearly bonkers, or they’re Black in the middle of the South, with such command that they could take over. They’ve got the thing. Now, that’s what I come back to. And I know that it’s such a boring answer, and people like to read all sorts of terrible impulses into this answer, but it’s a sincerely meant answer: You cast the person who’s right for the Doctor. You don’t say this time we’re gonna cast from this demographic and this time from this one—no, we’re not gonna do that, no. Because if you cast a part, any part, but especially a part as important as this, for any reason other than it’s the best person you can think of, the person you can’t get out of your head when you think of the part, if you do it for any other reason, that’s dishonest and our show’s going off the air. Guarantee it. There isn’t a single showrunner, a single producer who wouldn’t back me up on that. That’s absolutely true. If that person is a woman, then cast them, and to hell with everything else. And, are there women that could do it? Yes. A very, very small number. Are there other men that could do it? Yes, a very, very small number. There are hardly any actors or actresses who can play the Doctor, he’s quite special.”

The series’ other recurring Time Lord has indeed regenerated as a woman, though. The Master has become Missy, this time played deliciously wicked by Michelle Gomez. Like Russell Davies before him, Moffat was puzzled by what to do with the Master—the idea of the Doctor having an arch enemy seemed silly.

“He eventually hit on the idea of the Master being hugely unhinged with jealousy,” Moffat recalls. “I said, when I came along, I don’t want to deal with that character. Roger Delgado’s dead, and he’s amazing; what do we do with that character? And then we all talked about the Lady Doctor and in trying to at least turn the ship enough to say that one day that will be possible. It’s a big ship, it’s turns slowly, you have to keep in mind, or you sink them. But, let’s try the Master as a woman, because the Master is sort of the Doctor by a different name. So I said that’s what we’re gonna do, and I didn’t have a clue what to do with that character either. For ages and ages I’ve said said we’re gonna do this and we’re gonna have to cast it. And it was only when I saw Michelle Gomez’s name on the list for another part on the show and I said hang on, hang on, Gomez for Missy, because I’ve known Michelle for years.”

When Moffat found out Gomez had already been offered another part in the show, he was devastated. But then she sent him an email saying, “I’ve always wanted to be in Doctor Who. So I’m just writing you to say please consider me for any other any other razor-cheekboned villainess you want to introduce onto your show.”

“I didn’t even reply to her,” says Moffat. “I just went into the office the next day and said, ‘That’s it.’ Which is very unusual for me; I’m not usually that maniacal. But I said, ‘We’re not even going to have a chat about this; we’re just going to cast Michelle as Missy and that’s it.’”

“Michelle delivers a fabulous performance as the Master and is absolutely brilliant,” says Capaldi, “and I think that too much is made of the fact that the Master is now a lady and that people should embrace the quality of and congratulate her on what she’s done, being the Master so fully. Clearly the Doctor and the Master go way, way back, and Michelle and I come from the same place in Scotland, we have a lot of people in common, backgrounds in common, and I think that’s quite fun because the Doctor and the Master are the same. They came from the same background, the same place.”

So what about the future of the show that explores the future? With Coleman leaving at the end of the season, the question becomes how long before Capaldi follows. His predecessors left after one, five and three seasons, and he’s just completed work on his second.

“I guess you’d have to ask Mr. Capaldi, not me,” says Moffat. “I think he’s in a different place in his career than the previous two, who left as reluctantly as they did. I simply don’t know. The one thing you’d have to say about the Doctor is that it’s incredibly hard work. It’s incredibly hard work for that lead actor. It’s punishing. And you know, Peter’s 57. Matt was 26, and he’d never done anything as hard. And people will come to a point where they say, ‘I’d just like to go home now’—in the knowledge that no Doctor ever truly retires from the role. They just don’t. They remain Doctor Who. David still thinks he’s Doctor Who. Matt still thinks he’s Doctor Who. Peter Davison still thinks he’s Doctor Who.”

“I don’t know,” says Capaldi. “I like being Doctor Who. It’s my favorite part. In some ways, it’s not my position [to say], in some ways it is. I can’t say really. I’d like to do it for quite a long time, but we’ll see.”

As for Moffat, he says his job is also punishing but adds: “If I’m honest, I would have thought that I’d be tired of it by now, but I feel quite spry and excited and engaged with it, really, at the moment. I take it one series at a time. I would never just do a series of Doctor Who because I felt it was a contractual obligation or because I don’t want to give it to someone else. I’d never do that.”

“His voice is throughout the show,” Coleman says of Moffat, “his humor, his imagination, his quick-wittedness, his sharpness. Having so many layers and also within one episode and also the way he can pepper and arc the story throughout the series—I think is quite incredible. It’s a really, really dynamic show that’s always moving and never does it patronize and it appeals to four-year-olds, it makes them laugh and kind of appeals to a 78-year-old, and that all boils down to Steven’s writing.”

“Yeah, I think that the expanding success of the show has to be put onto him,” Capaldi agrees. “What people don’t understand is that if you’re a showrunner as good as he is, one of the great legends, is that he will come in if you’re having trouble with a script and with one fabulous idea, turn that script around. And so his influence on the material and on the other writers’ work is major. Because he’s such a huge fan of the show, his connection to it is very deep. He absolutely loves this show. He’s the person that makes it. If you ever see an episode of Doctor Who and think, ‘Wow that’s the best thing I’ve ever seen,’ it’s because of him.”

What we do know about the future of the show is that there are six episodes left this season and, as always, a Christmas special coming up. We also know that the two-parter starting tomorrow night will involve a full-on Zygon invasion and take Clara to a darker place than we’ve seen before. We know Maisie Williams will return in episode 10 but is unlikely to replace Coleman as The Doctor’s traveling companion (the last time we saw her, both she and The Doctor agreed that the last thing two centuries-old travelers need is each other). And we know that when you go to your Halloween party this weekend or open the door to trick-or-treaters, you’re likely as not to see someone dressed as a TARDIS or one of the 12 Doctors or a Weeping Angel or Dalek or something even more obscure for the show’s 52-year history. The Doctor has become such a part of the pop culture that it’s difficult to imagine a future without him.

Josh Jackson is Paste’s co-founder and editor-in-chief. He may or may not have built a TARDIS soap-box derby car for his children to race.