"I wish I could say how wrong or right you are, but you guys have to wait just like we did," Simpson tells THR about the Man in Black fan theory.

[Warning: This story contains spoilers from the fourth episode of Westworld.]

The artist occasionally known as Liam McPoyle is a long way from Philadelphia.

Jimmi Simpson, who regularly grosses out the gang (and viewers) on It's Always Sunny in Philadelphia as part of the McPoyle family, faces different gangs and families altogether on HBO's Westworld. On the HBO drama, Simpson plays William, a young man visiting the high-tech wild west park for the very first time, alongside his colleague and soon-to-be brother-in-law Logan (Ben Barnes). Unlike William, Logan is a Westworld veteran, with zero reservations about giving into the park's hedonistic universe. For his part, William has viewed Westworld through a cynical lens… at least until meeting Dolores (Evan Rachel Wood), the oldest host in the park.

The fourth episode of the series, called "Dissonance Theory," saw William traveling alongside and bonding with Dolores. Even knowing that she's not human, William couldn't help but be drawn to the host's innocence. As Simpson describes it: "This is the first kind of soft and passive element of Westworld, and it draws his attention."

But will it always be the softer sides of Westworld that catch William's eye, or will he become more immersed in the expansive reality's darker corners? Some fans believe that William is actually a younger version of Ed Harris' enigmatic Man in Black, with the William story playing out several years earlier than the rest of the Westworld storylines.

Understandably, Simpson is tight-lipped on the subject when it comes up. ("I wish I could say how wrong or right you are," he tells The Hollywood Reporter, "but you guys have to wait just like we did.") He's more forthcoming about the broad view of William's backstory, his views on the park, his attraction to Dolores, his take on Logan and, most importantly, how the McPoyle family would handle a trip to Westworld.

William and Logan are introduced in the second episode, and at least on the surface, they come across as the show's version of Richard Benjamin and James Brolin's characters from the original movie. Was that a starting point for you?

No, it wasn't. I hadn't seen the movie since I was very little. But I remember loving the premise and loving Yul Brynner and certainly Richard Benjamin. I didn't see it [again] until halfway through filming. Clearly it's a seedling, along with malfunctioning A.I., that [showrunners Jonathan "Jonah" Nolan and Lisa Joy] took from the original. But like the A.I. malfunctioning, that's kind of where it ends. Those ideas, yes, but the specifics of the characters are different, and the trajectories of the characters are very different.

How would you describe William, both in a general sense, and also his view of the park?

William comes from very little means. He's worked very hard to get this budding position at a company. He's uncomfortable with complete exercise of his id, or the feeling that he's entitled to anything. A situation like [Westworld] is something he would never choose. He's brought in there by his fiancee's brother and boss' son — both of those people are Logan. It's sort of a vetting of William, to see if he fits into the family. That's why he has less of an agenda than almost any other guest, who's there to f—k or fight or do whatever. He's pulled into a situation he did not choose. He's not going about it the typical way. He's there, and he doesn't want to shoot things. Because he's there unwillingly, he's a little bit more observant. His journey is about having those expectations removed, and therefore, anything can happen.

We're slowly learning more about William's backstory. Every episode there's a new piece of information. We now know that he and Logan work together and are soon-to-be brothers-in-law, and that Logan views this as a work trip of sorts. How much did you know about William's backstory and the arc ahead, going into the series?

Very little. Almost only what I needed to know from moment-to-moment. A relatively rich backstory was given to us by Lisa and Jonah, as far as who these people are, how they feel about certain things, and kind of what their aim is in life in general. But as far as the arc of this part of the story, for each of these characters, nobody knew anything. All the actors were in the dark. If we were given a scene that you somehow needed more information to play for your process, Jonah and Lisa would be there and enlighten you on anything you needed to know. As far as knowing what's about to happen, we were all just as hungry for the scripts each month as you guys are for the episodes each week.

Until this episode, William's interactions have been mostly limited to Logan. What's your view of that character, someone who is considerably more hedonistic than William?

Most of us aren't Logan. Most of us don't get to choose everything we're doing in life, and William in particular. We all have these acquaintances and friends who are spiky as hell, but they're there, so you modulate your reactions to them and you accept it. It's like your wife's best friend's husband that you have to have dinner with every month, and he's a f—king dick. (Laughs.) It's that. "This is someone who is in my life, and I'm going to get through it as much as I can." Most of that is gritting your teeth and putting up with it, and sometimes, they strike a cord and resonate with you and make you laugh, and their different point of view actually is kind of enlightening. It's that kind of thing. He's not there by choice necessarily, but he's there.

In this episode, William and Logan are on a mission to capture a bandit named Slim. They succeed, and everything's going well, until Logan shoots the sheriff they're with so Slim can lead them on a more dangerous journey. This happens just as William is finally starting to find his footing here in Westworld. He can't be pleased with this sharp turn for the black hat.

No, not at all. He's been trying to figure out how to make this adventure be okay for this new being [Dolores] he's run into, too. So it's complicated that much more. So no, he's really not at all thrilled. But that's the joy of Westworld. He doesn't get to make all of his choices. He's choosing to get to know this new being, as opposed to have his way with her, but Logan's the one who chooses which environment they're going to be in together.

Speaking of the new being, it seems that William and Dolores established a connection right away, back at the end of episode two when William picks up Dolores' fallen can of food. What do you think William sees in Dolores?

First of all, Westworld is designed to give you everything, in a very aggressive way. Like when Clementine comes at William, or how the violence is offered up to your face. This is the first kind of soft and passive element of Westworld, and it draws his attention. He offers something to this host, as opposed to it being offered to him. I think it strikes him as, like, "This is an anomaly, and maybe a slight familiarity." But it's not like he noticed much more than that. As she drops in his lap, it's this need. She needs him. It's not just this offer. I think it's something he can relate to: helping, as opposed to destroying. In episode four, I think it's so interesting the way Jonah and Lisa wrote the development of this relationship, by basically showing how truthful Dolores' reality is to her. At the same time, Logan's articulating to William: "Yo, this is a trick. It's just to get you invested, and it's working, you sucker!" And he doesn't want to be a sucker to Logan. He knows it's a fact. And he's thinking about this as she's describing her life to him in the most beautiful tapestry. He's more and more interested. He knows what the truth is, but he keeps giving himself more rope, because it's just that real. I think the experience after four will be… well, where does it go? We know that there's an end to the rope. Everybody knows that. So what's going to f—king happen? It's this thoughtful allowance of an artificial being to enter your heart.

And that's on full display in this scene between William and Dolores when she says, "Sometimes I feel like something is calling me, and there's a place for me beyond all of this." William buys into that moment: "I know exactly what you're talking about." It's a great example of how the reality of Westworld can make even the greatest cynic open themselves up to the experience.

It's so true. It bends even the most rigid of minds. You get to see it happen in that very scene.

By now, you must have heard about the theories that William is a younger version of the Man in Black.

Oh, yeah.

What's your take on the theory?

First of all, I'm just flattered, because that man is so bad ass. (Laughs.) Second of all, I can't comment on anything. I wish I could say how wrong or right you are, but you guys have to wait just like we did.

You wouldn't want to shut down the theorizing, anyway.

Exactly. Bring it on, because we literally all did this every time we got a script: "Oh my god! This is happening! She's this, and she's not this!" Then we were generally wrong, but sometimes, we were a shade right, and you would feel like a genius for somehow figuring out Jonah and Lisa's brilliant puzzle.

Is there an inevitability at all to some kind of collision between William and the Man in Black, if they're serving as the show's version of the Benjamin and Brynner characters from the movie?

I wouldn't say there's an inevitability, just because… I love all of the Benjamin references and the references to the film, but the way I describe William and Logan to someone who has seen the movie, is that it's as if they took Benjamin and Brolin and put them as the fifth storyline. The first storyline is the POV of the hosts. Jonah and Lisa completely flipped it around. I wish the series was all about my character ending up somewhere, but it's about the hosts. I don't want anyone's expectations [to get up for] the wrong journey. It's the hosts' journey. Don't expect it to end in any way like the movie.

The Man in Black aside, what would it take for someone like William to go full black hat? Because that's where we're left off at the end of the episode: Logan asks William to "go black hat with me," which feels like the complete opposite of what we know about William right now. If William ever were to go fully in that direction, what would have to happen to that man for him to go there?

William's there to open up his world. He's certainly not there to turn into an asshole. And the end of four, it's not like Logan is saying, "We're going to go f—k shit up." It's, "We're going in this direction." William is going to be part of the experience, but he's also going there to protect Dolores. It's not that William has agreed to go and be a dick. He's agreed to go on this new direction of a place, and meet Slim's boss. It's more of an acquiescence: "Ugh, fine," than him saying, "Alright, I'm going to go black hat."

Final question… how would the McPoyles handle Westworld?

They would never pick up on the fact that everyone else was a robot. They would think they went to heaven, and would probably start making sausages out of the robot horses, and would have no idea that it tasted so shitty. They would start a whole empire: the McPoyle Sausage Empire of Sweetwater.

It would be hard to know if they were hosts or guests, too, because there would be flies crawling all over them…

And they really wouldn't swat them away. (Laughs.) They would be their friends.

Follow THR's Westworld coverage for more interviews, news and theories.