In a new interview this week, Star Trek: Discovery showrunner Alex Kurtzman spoke about the challenges of recasting characters from the original Star Trek series for the upcoming second year of his show, and also shared some more detail about how the Spock / Burnham relationship will drive the Vulcan character towards his Original Series persona.

Speaking on the Variety “TV Take” podcast on Friday, Kurtzman talked about his experience recasting Number One (Rebecca Romijn) — and for the second time, after the 2009 Star Trek film, Spock (Ethan Peck) and Christopher Pike (Anson Mount) for Discovery Season 2.

I think maybe I was a little bolder [at casting Original Series characters] because we did it in the [Kelvin Timeline] films, so I felt like I had touched that area before, and was so proud of the amazing work that the actors did, and felt like, “Okay, I saw it happen once, maybe we can do it twice.”

It’s always dangerous, because the TOS characters are so beloved, and everyone has such a strong opinion and such strong feeling about each character — and if either the recasting or the characterization itself doesn’t meet up with people’s imaginations then we get into trouble.

Knowing that, however, I guess maybe I’m really dumb and like to dive right into the fire, but I really enjoy the experience of it because I have my own connections to them too, and felt like what was really exciting was the opportunity to explore a grey area about this relationship and these characters, Spock and Pike… and Number One.

Number One’s a great example, you know very little about Number One, right? She was in one episode, and then kind of out, and she’s a blank slate – and yet, she’s always been remembered by Trek fans. Pike was obviously a character who had a large mythological presence on the show, both because of the pilot that never aired, and what came later in “Menagerie” and then what we did with Bruce Greenwood [in the Kelvin films]. We got to open more doors in his character, but that obviously is the Kelvin universe, so it’s a different version of Pike.

I loved the idea of saying, “Okay, who are these people, really?” And we have fourteen episodes to explore nuances and details and parts of their lives that either may have been alluded to, or left blank that we can now fill in.

Kurtzman also talked about the lengthy casting process that lead Discovery producers to select Ethan Peck to take on the legendary character, first revealed to the public last August — as well as looping in Leonard Nimoy’s family on the process.

We did an extremely deep dive on casting, and spoke with the Nimoy family, and had them bless the casting. When Ethan [Peck] came in — and when I say he was probably the over 400th actor we had seen, I mean that literally — what I saw in him were two things.

First of all, he conveyed to me… that he too was struggling with something similar to what Spock was struggling with. I could sort of see it between the lines of what he was actually saying in the dialogue he was reading. And he didn’t know he was reading for Spock.

That, coupled with the fact that he was so clearly ready to dive wholeheartedly into this, once he understood what was actually happening and who he was playing, he was so beautifully committed to saying, “I’m going to go as deep as I can go here. As deep into this character as possible, and I’m humbled and terrified. I’m living in Leonard’s shadow, I’m living in Zach’s shadow.”

What I always felt was that his fear was great, and I said, “If you weren’t scared right now, something would be wrong. It would be bad!” It’s a huge responsibility that we both have, but we’re going to hold hands and we’re going to go through it together.

[…]

I think [the Nimoy family] was very moved that we were carrying on the legacy in a way that felt relevant and fresh. The fact that they were consulted, the fact that we weren’t just going off and doing it… we all owe a debt to Leonard. I, certainly, having known him and loved him, would not have every felt okay about that.

Finally, Kurtzman also shared some more background on how — as Discovery is set after the events of “The Cage,” and several years ahead of “Where No Man Has Gone Before” — the relationship between Spock and Michael Burnham (Sonequa Martin-Green) will prepare the Vulcan for his ongoing interaction with humanity.

Maybe part of [balancing Spock’s character in ‘Discovery’] is that, having written a version of Spock for Zach Quinto, and then having had the opportunity to work with Leonard [Nimoy] on a different version of what Spock becomes in the prime universe — and having so many conversations with him about who he imagines this character to be — allowed us the freedom to say, “Let’s fill in a blank for why this character would never have mentioned his sister.”

There has to be a really, really compelling reason that we went through TOS, the movies both in the prime and Kelvin universe, and he never said a word about her. The challenge of that, figuring out how to make that work, emotionally, and how to make that work on a plot level, was so juicy, that I think we just felt we had to go for it.

Look, I’m a huge sucker for a sibling story, I just am. It’s one of my favorite kinds of stories, because I think it’s so rarely told. It’s such a unique and specific relationship, and you don’t necessarily have to be a blood sibling to connect, and have a very distinct and unique connection.

So the idea that Spock and Burnham are playing out this dynamic of logic versus emotion, and knew each other before Spock became the character we meet in TOS, was so exciting to me because I think what got me riled up about it is the idea that if we can take Season Two of “Discovery” and understand how his relationship with Michael informed how he became the Spock we meet in TOS — that without that relationship, he would never have been prepared for Kirk — that’s a new and interesting spin and something really worth talking about, because people haven’t seen that.

Star Trek: Discovery returns on January 17 with “Brother,” the season two premiere, directed by Alex Kurtzman and written by Ted Sullivan, Gretchen J. Berg, and Aaron Harberts.