Mark-Paul Gosselaar had just finished “Pitch,” Fox’s one-season baseball drama in 2016, when he took the role of Brad Wolgast in the network’s adaptation of “The Passage.” After some behind-the-scenes retooling, which included a restructuring of the pilot script, attaching a different director and some re-shoots, “The Passage” was ordered to series in May 2018 and will premiere Jan. 14, two years after the pilot was ordered.

“I’ve never been a part of something like that in my career,” Gosselaar tells Variety. “Generally if you do a pilot and it’s not working, you move on — and if it is working, you get picked up.”

Gosselaar says he was first attracted to the project in part because of it being a genre show, and “genres are working right now,” but also because of the caliber of people that were already attached, specifically showrunner Liz Heldens, as well as executive producers Ridley Scott and Matt Reeves.

“I was like, ‘Oh my God, this is amazing, I can envision it,'” he says. “So you’re on board and you’re expecting it to only get better and expand. And then you read the books, and it does.”

Here, Gosselaar talks with Variety about how the extra-long process for “The Passage” to make it to air affected his work on the show, what expectations he had based on his love of the books, and what he learned from working with Donald Sutherland and Dennis Franz.

How did all the behind-the-scenes changes on the pilot affect your work?

To be pushed almost a year was difficult creatively, financially — it ties you down as an actor. Other doors have opened up, and my development has really expanded, but that was really the toughest part. As an actor on the show, it didn’t affect anything. It was a really well-oiled machine, and the caliber of the cast, the writers [was high]. And Atlanta’s not bad.

Was there a time when that was happening that you considered dropping out of the show, and if so, what pushed you past that moment to stay?

Oh yeah, absolutely. My relationship with 20th, my relationship with Fox — I trust them…I feel protected. Since working on “Pitch,” I’ve been given opportunities with them and they’ve allowed me to do other things, which other networks in the past have not. So I have a good relationship, and to walk away from a project like this wouldn’t have been good in the long run.

You mentioned Atlanta. It’s not the first time you’ve shot there, but what do you think it’s added to this process and this show?

The pilot of “Franklin & Bash” shot in Atlanta and when it got picked up they said they wanted it to be set there, but Breckin [Meyer] and I were like, “Nah.” I was going through a divorce at the time, and I wanted to be close to home. This is the first time in 20 years that one of my shows is not filming in Los Angeles. I see the importance of filming this there. I think the money that we save [due to tax credits], we can put back into the show, and the show needs it. It’s a large show; it’s ambitious.

Is it helpful or more overwhelming to have so much backstory of a version of your character at your fingertips, given the book trilogy?

Most of the jobs that we take, we don’t even have the amount of information that we have in the books. When you look at “Pitch,” as a good or bad example, it was written like a very Mike Piazza baseball player — the long hair, playboy kind of guy. And as an actor, I’m not that, I didn’t go into the room like that, and I made Mike Lawson my character. And so when I got the script that Liz wrote and Marcos Siega was attached to, I read that, and I was excited. … To read my character and his relationship with Amy Belafonte, it sort of took me by surprise — to have that kind of heart wrapped around a genre piece.

And it changed your expectation?

That’s exactly what happened. I read the script, I walked in the room, and then I read the book. I really liked the book, but then Wolgast dies, and I’m thinking, “Oh it’s a bunch of virals and stuff, he’s going to come back — he’s going to be a viral.” So then I get the second book, and it’s about Lila, and that seems like a good opportunity for Brad — [his] name is in it — but he’s not in the second book. So then I get the third book and I go right to the search — because I’m reading on my iPad — and I go “Brad Wolgast,” and there’s nothing. I go, “Holy s—.” So I call my agents and I go, “Did you guys read these books?” “No.” “My character dies in the first fourth of the first book.” And they were like, “Well, you know that’s going to change.” But part of me, as a fan of books, is like, “Don’t change it too much because it’s perfect just the way it is.” So I am on for however long they want me on.

How does having all of that in your head affect the choices you make as an actor early on? Are there specific things you want to seed for the future?

No, because I really feel what we do in this business is a collaboration. We can’t do what we do alone, and in a way, it isn’t my job to think that way. I have to trust Liz, I have to trust Matt, and just let it be. And if I’m there to the end, great, and if I’m in it for one season, I’ll be bummed, but that’s the business.

Are you looking for surprises from the show? Not necessarily ones that would keep you around longer, but just something different to expand the story even farther than what you and other readers are expecting?

I never — and maybe I should — but I never think that way because I feel, as an actor, on a project that I haven’t developed, that is not mine, that I’m along for the ride in a way and that I bring colors to a portrait that’s already there. And that’s sort of the challenge of doing what I do. When the pieces don’t make sense, then I can express that, but in terms of wishing or hoping, obviously I always want to be challenged every week on every script, but that’s not always going to happen.

As a fan of the books, what was your reaction when you saw what the virals looked like in the show?

It’s weird, part of me pictured them the way they are on our show, but Justin did this weird thing where they were lights — beams of light — and I didn’t always see it that way, that wasn’t as menacing or as dark as I would have liked. I like dark, so I like “The Strain” and those type of things, so I like where we are in our virals. And it’s an interesting take with what they’re doing [with] as the virus is working better, you see more of the person. I thought that was a cool interpretation of it all.

What was most important to creating a relationship with Saniyya Sidney, who plays Amy?

We shot the pilot in a linear fashion, so it came natural. That doesn’t normally happen, by the way. When she met me, she was very guarded, and I thought, “Is she acting?” And it turns out she wasn’t, she just didn’t know what to really expect from me, and it played on the screen that way. And then by the second week we’re filming the scene where we’re at the river, and we were very fortunate to film it that way — otherwise we would have had to act more. But no…I think it makes it easier, especially for someone who’s as new to the industry as she is, as a 12-year-old. She’s amazing, but it helped to film that way.

Is your process different with her than some of the other actors?

I watch what I say! There’s a swear jar that we keep, there’s a tally, and I’m now in debt. I am much more open to rehearsing and asking if she needs anything — and she really doesn’t. She’s so put together.

What do you think it adds to the story that Amy has been aged up from where she is in the books?

I thought it was an amazing character as a six-year-old, but that’s the film version, if you can shoot for three months. We have to look at it with the possibility of years, being on-air. On the production side, it’s even difficult now. She’s 12 years old, we have to work around her schedule. I remember the scene where we were filming the carnival scene [which] we shot at night, and to work it into her schedule with her coverage, there were times she wasn’t there and I worked with a double. The big fight scene in the re-shoots, we did that scene with me fighting the guy in the room, and I put her underneath the desk because it took all day to do the piece in the hallway, which is only 20 seconds on film, and we got to the end, and we were fighting time with her. And that’s the reason she was underneath the desk, the way we filmed it, we had 30 minutes to film. I was fighting this guy for six takes, we left the cameras rolling, and we got what we got.

What is the overall vibe you want to create on-set, and where has it come from?

I’ve seen amazing examples of generosity on the set and being a team player, and as one person said it, “I’m an actor, this is what I do.” That was Donald Sutherland who said that. I was in a scene on “Commander in Chief,” and he was talking to somebody at the other end of the room, and my character references him, and he references me, but on his coverage I was there because of the way the shot was, and then on the turn-around, it was my coverage, and we were filming in a remote location where we couldn’t get the trailers in so it was a drive to get back and forth from the trailers. So I was on-set, and they said, “We’re going to hold for Donald to come in for your eye-line,” and I was like, “I don’t need Donald for my eye-line. Just put a piece of tape on a c-stand and I’m good. Why bring him all the way back? I don’t say anything to him.” So they were like, “OK, we’ll let him know.” But he comes in — and he’s an imposing guy, and he was wearing this big parka — and he comes up to me, and he said, “Did you say that I don’t need to be here?” And immediately I start backpedaling, and I said, “It’s not that I don’t need you — whatever you want to do, sir.” And he goes, “Listen, I’m an actor, this is what I do.” And he walked over, and he was my eye-line.

The other person that I learned a lot from was Dennis Franz. I worked with him for four years, and every single day that guy came prepared, he was happy to be on set, never once complained about a thing. He didn’t complain about the words that were on the page. If he had concerns he had already discussed [them] with Steven Bochco after the table read, which is the way to do things — don’t wait until the day you’re shooting to say “I can’t say this.” So when I saw Dennis working, he was such a generous, genuine — the guy you looked up to on the set. There was this great synergy between the set and the production, and he created an environment that I said, “That’s the environment I always want to work in.” So I’ve been lucky enough, if I’m No. 1 on the call sheet, to kind of set that tone, but it’s just however you want to be treated, treat other people like that. You’re not a nice person unless you’re a nice person to everyone. … And I’m so glad I can work, at this point in my career, with like-minded individuals and not have drama. It just makes for better television.