For Taylor Kitsch, preparing to play David Koresh, the leader of the Branch Davidians who became involved in a 51-day standoff with the FBI in the early 1990s, wasn’t just about learning his family history or reading scripture. It was also about making a physical transformation.

“I’ve never been more scared,” Kitsch tells Variety of taking on “Waco.” “He was this enigmatic guy that I wasn’t sure how to get to, so I started losing weight. I was looking at Day 30-something of the siege in the script, and I wanted to get to that physically. It wouldn’t make any sense if I looked healthy and muscular and whatever my frame was at the time. You have to look like you went through hell and back. You walk and wear clothes differently.”

Kitsch is no stranger to playing “guys that have lived and died and left some kind of legacy,” and that kind of commitment to go the extra mile is exactly what the writers and executive producers of “Waco,” Drew Dowdle and John Erick Dowdle say they were looking for in their leading man.

“The real David Koresh was great looking. He was funny and charming and all of these things,” says John Erick Dowdle. “So we wanted to find someone with movie star looks, but also somebody who really wanted to dig in. And when Taylor raised his hand, and his agent sent photos of him and Koresh side by side, and we were like, ‘He looks just like him!’ But then he showed up, and he was studying scripture, learning to play guitar, he lost 30 pounds. He played full-tilt.”

It was also important to the Dowdles that they didn’t cast someone who was excited about playing “a raving lunatic” — because that is not how they saw Koresh, nor how they were writing him.

“He saw David as we saw David — as an interesting guy who was misunderstood,” Drew Dowdle says about Kitsch. “How Taylor portrayed him was very much about how did the people inside view him? He was a person with many layers, and a lot of them were good, but some of them were bad.”

The Dowdles set out to tell the story of the siege at Mount Carmel in shades of gray from both sides — the Branch Davidians who were led by Koresh and the FBI agents who stepped in to clean up a mess after the ATF attempted to raid the compound.

“One of the biggest challenges was how you take all of this stuff about Waco and who you choose to follow. Let’s find the heroes within this bad situation. Let’s find those who tried to understand the other side and look for the humanity in the other side,” John Erick Dowdle says.

Some of the heroes the Dowdles saw in the story were former FBI hostage negotiator Gary Noesner, who spent hours on the phone trying to convince the real life Koresh to bring his people out of the compound, as well as David Thibodeau, a survivor of the tragedy. Both men wrote books that were key pieces of research for the producers, and both men were not only depicted within the series but also served as consultants of sorts for the actors who portrayed them.

“Realizing what it was going to cost him to go down this path, we took very seriously,” Drew Dowdle says of Thibodeau.

Thibodeau has been involved in some documentaries about “Waco” in the past but feels that they often have been one-sided, out to talk only about the preconceived “cult” narrative of the Branch Davidians. The Dowdles, though, were interested in the “tale behind the tale,” which is what made him comfortable signing onto their scripted version of the story.

“It’s incredibly important to show more of the depth to it,” Thibodeau says. “I want the people to be honored — the people that died — instead of so damn demonized people have no idea who they are. So the fact that some of their stories are being told is phenomenal to me.”

Rory Culkin, who plays Thibodeau in the series, says what he connected to most was the idea of being an “outsider who was accepted into this group.”

“I like to say that I approached the role in a similar way to how Thibodeau approached the Davidians, which is with a little skepticism, mostly curiosity and just fascination,” Culkin says. “Things that took weeks of explanation for David, I had to express in one scene. I had to be convinced of the New Light revelation by the end of one scene, and I wasn’t sure about that, and I hope it comes across that I wasn’t fully convinced. It’s a balance between intrigue and skepticism.”

Having only six episodes to tell their story, the Dowdles’ “Waco” does leave out a number of people from Koresh’s past, and it condenses some people into amalgamations. While they felt it was important to be factual about how “divided” the FBI was, they also wanted to “create a discussion” around what it took for things to get so bad.

“The FBI stepped into a situation where what it looked like to them was these insane religious culties opened fire on the ATF and now they had to come in and clean up. What was really interesting on their side were the philosophical differences between tactical and negotiators. The negotiators were willing to wait forever, and tactical, their patience was running thin almost immediately,” John Erick Dowdle says. “The side we really wanted to make sure we portrayed not in any villainous way was the HRT side and the tactical command. Let’s understand why they were so impatient so their actions don’t seem like they just wanted to kick a–.”

All involved in the series want the audience to be able to draw their own conclusions about Koresh and what transpired during the siege. Looking back on his own experience, Thibodeau acknowledges that it was a time that came with great tragedy in the end but still has fond memories of life with the Branch Davidians before the siege. In fact, he says that visiting the set, which was a painstaking recreation of the compound, was like “coming home” in a weird way.

“I would love to be able to say that David was just an ultimate manipulator and he was so good at what he did and we all made a mistake. If I could say that, my life would be so much better because I’d be able to move on, [but] I can’t say that,” Thibodeau says, adding that he has read countless books about mind control. “I can’t say it because I had things happen to me on so many different occasions that I can’t explain. There will always be a part of me that wonders — that believes. At the same time, I’m not an apologist for David Koresh or a justifier for what he did. And I’ve always believed eternity is an energy and a force. I don’t believe we’re meant to just die and go to nothing. I believe there is justice in that force. There’s no justice in this world where people can screw up and kill people and get promoted while the families of those who were lost get told their son or daughter was a cult member or a criminal. But here’s my point: everyone is going to have to answer to his God, David included.”

And just as Thibodeau was forever changed by his experience with Koresh, so too were those involved in creating the Paramount Network series.

“I feel like this has forced us to reach beyond what we naturally would have otherwise,” says John Erick Dowdle. “It just meant so much being with these actors, doing something we believed in, and doing something that mattered in a different way than the work we did before. That’s changed me. I want to make films that mean something deep.”

Adds Drew Dowdle, “In this highly-charged political atmosphere we live in now, I try to remind myself no matter how different I think someone might be based on the things they post on Facebook or whatnot, if you just sat down and had a conversation with them you probably have a lot more common ground than you might think. There is something about actual human communication. There’s no substitute for that.”

“Waco” premieres Jan. 24 on the Paramount Network.