Josh Rivera walks differently when he’s in New York City. He’s not necessarily aware of it. It’s more of a habit. “My girlfriend is funny about it,” Rivera says of Rachel Zegler, the actress he starred with in West Side Story And The Hunger Games: The Ballad of Songbirds and Snakes“She still teases me about it sometimes.”

The 29-year-old struts a bit to make himself look more impressive, or at least to give the impression that strangers shouldn’t mess with him. It’s something that dates back to his high school days in Boulder, Colorado. As a teenager, he played football, but he was also involved in choir and drama, including musical theater. What’s more, his family moved around a lot, and he found himself changing his physical aura to fit each different school clique or environment. “I don’t know if it works,” he says of his walk, “but it’s just what I find myself doing.”

The actor questioned his New York bravado after landing the title role in FX’s American Sports Story: Aaron Hernandezabout the New England Patriots tight end convicted of murdering semi-pro football player Odin Lloyd. Like most professional athletes, the Hernandez of the new anthology series projects an aura of machismo, which he often uses as a front to hide his sexual relationships with men. Like the real Hernandez, the character commits suicide in prison after being outed in the media.

Reflecting on his walk, Rivera notes, “I think everyone does a version of that on some level. I knew some of what’s known about his relationship with these more masculine figures and his attempt to emulate that. I tried to tap a little bit more into what it feels like to adapt to different environments and different scenarios.”

There are many layers to Hernandez’s role and the larger sports cult that American sports story attempts to dissect. Led by frequent Ryan Murphy collaborators and executive producers Nina Jacobson and Brad Simpson, the first season follows Hernandez’s private and public lives. Over the course of 10 episodes, we see him as a child living under the thumb of a father who punishes weakness, as a teenage prodigy athlete in a very private relationship with a boy named Chris (Jake Cannavale) while publicly dating his future fiancée Shayanna Jenkins (Jaylen Barron), as a rookie at the University of Florida where he played opposite Tim Tebow (Patrick Schwarzenegger) for the Gators, and as a man struggling with drugs and the long-term effects of a football-related head injury, all leading up to the fateful moment when he kills Odin.

“This is our sport as a country,” Jacobson says of soccer. “We’re the only ones who are really in it. It’s a huge part of the economy and our identity. So (we wanted to) explore all of these themes in there, of the commodification of black and brown bodies, and all of the moments throughout the course of this story where ‘Football Inc.’ might have done something different in relation to this: a guy getting in trouble, showing signs of danger, but as long as that danger was on the field, it was removed from the field until it couldn’t be anymore.”

Rivera has a “little conspiracy theory,” as he puts it, about why he was cast. The actor worked with Jacobson and Simpson on the Hunger Games prequel film, in which he played Sejanus Plinth, once a mentor to a tribute in the games who was forced to become a Peacekeeper soldier in District 12. He had a bald head for the Peacekeeper portion of the role, during which time Jacobson wanted him to listen to the Aaron Hernandez podcast Gladiatorfrom Wonderly and The Boston Globe —the same podcast that the producers adapted for American sports story“After a few weeks I got an audition tape for it,” he recalls.

Rivera tried not to get too emotionally invested in the audition in case he didn’t get the job, but once he did, he dove headfirst into the research. “It was hard for me not to care whether I got the job or not, because from an actor’s perspective, the more complex something is, the more interesting it is, the more questions you have to ask yourself and the more you have to delve into your own psychology, and that’s why I like it,” he says.

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At first, fear struck. Rivera was (and still is) very conscious of walking the line between imitation and emulation. He wanted the latter, not the former, with his performance. Imitation, he says, doesn’t serve the story. “It’s a pretty daunting prospect to feel like you have to be someone else that someone else can fact-check very easily,” Rivera explains. “At some point, I have to choose a characterization, which is really hard and a big risk. You don’t want to be disrespectful or anything, but I felt comfortable and confident with the amount of material I was given and with the team around me — but it was overwhelming at first. I’m not going to lie.”

What put him at ease was the approach of showrunner Stuart Zicherman (The Americans, The psychiatrist next doorThe season is an adaptation of the Gladiator podcast, and any adaptation comes with certain creative liberties. “It gave me a lot of freedom when the showrunner[said]we’re going to touch on a lot of things that aren’t known, we have to tell the in-between stuff,” Rivera continues. “That gave me a little bit more freedom to take the essence of this character, use the public appearances that I see, use the differences in the intonations of the way this person talks to their family versus their friends, and then use that to drive my own characterization. It’s true, it’s kind of a tricky line[to walk]because you don’t want to be beholden to what everyone else knows about someone. It’s a different story. It’s an adaptation, it’s not a documentary.”

Rivera was also tempted to dust off his youthful football skills. For the high school sports scenes, producers cast background actors who appeared smaller than their stars to emphasize Hernandez’s size on camera. “I did a lot of those high school football (scenes), and I kind of got too big for my britches there,” Rivera admits. When it came time to film the college scenes with the Gators, “everyone was huge, man,” he recalls. “I was like, ‘What happened?!'” Perhaps it was his walk around NYC and his experience bouncing between environments as a kid, but Rivera adapted anyway.

“‘I’m gonna do the stunts, I’m gonna do the football.’ And I got beat up, man,” he recalls, laughing. “I think I did about four or five setups and I was like, ‘I can’t do it, I can’t do it.’ Football is pretty tough. Who would have thought?”

American Sports Story: Aaron Hernandez premieres September 19 on FX and Hulu.