One plays a struggling lawyer; the other, an accomplished doctor. When Bob Odenkirk (“Better Call Saul”) and Michael Sheen (“Masters of Sex”) sat down in Variety’s Actors on Actors studio, the two thespians found common ground over the challenges of playing the same character over several seasons — and their wicked sense of humor quickly shone through.

Michael Sheen: What made you sign on for “Better Call Saul”?

Bob Odenkirk: I played Saul Goodman in “Breaking Bad,” so they had to give it to me. They were completely screwed.

Sheen: Were you the first choice to play Saul?

Odenkirk: I heard that I was. Everyone else was sick or working or underage.

Sheen: It’s hard to think about anyone else playing that part now.

Odenkirk: I’m told that (casting director) Sharon Bialy had me at the top of the list, and that Peter Gould, who wrote the episode called “Better Call Saul,” said “Wow, that’s who I was imagining.” So before they’d planned or discussed it, two different people had thought of me for it. Which is weird to me, because I never understood why they gave me the role. I thought maybe it was because of “Larry Sanders.” Because there’s some similarity between Stevie Grant and Saul Goodman. But Vince (Gilligan) told me it was “Mr. Show.”

Sheen: Really, it was “Mr. Show” that did it?

Odenkirk: What piece of “Mr. Show” I don’t know. I mean, we were being very broad and silly. I was just doing sketch acting the other day with David Cross, and it is very different. Because you can just be a big idiot in sketch comedy. It’s just nothing like the kind of focus that dramatic acting takes.

Sheen: If you’ve been doing a lot of sketch comedy where you’re essentially playing characters for a very short amount of time, you’ve gone the other extreme where Saul could be one of the longest running characters on any cable TV show, because of “Breaking Bad” first and now “Better Call Saul.” I know people play the same character for a long time on network shows, but on cable shows that doesn’t happen. Saul could be the longest-running character of all time.

Odenkirk: We’ll see how it goes. Now you are doing a character who is very contained.

Sheen: That was one of the things that made me want to play the character, because he was so different to anyone I’d ever played before. I’ve never played a character where there’s not more going on o n the outside. To just play a character where it’s all going on underneath, and you don’t really show it so much — that was quite scary, but also quite attractive to begin with.

Odenkirk: And as the show progresses we see these sides of him.

Sheen: That was the challenge. And that’s why I think that’s why I really only would have played this character in this medium. Over a 90-minute or 110-minute film, you can’t reveal stuff.

Odenkirk: How much did you know about the growth of the character from the beginning?

Sheen: I started talking to the writers and our showrunner Michelle (Ashford) about what the journey of this character might be. Because he’s a real person obviously so I could read the biographies. What I got interested in was the idea of someone who to begin with was so cold and difficult to read and kind of alienating, but by the end of his life, he was this very warm man that everyone really liked very much. It’s almost the reverse of “Breaking Bad” in a way where you go from being this very difficult man to someone who is much more likable. I liked that idea, and I thought, because of the way episodic TV is going, certainly on cable, you can really get into the complexity of people. So I probably wouldn’t have played a character who was like this in a film or a play, because it’s not enough time to really explore it in the way I wanted to. But over a show like this, you can really do it.

Odenkirk: It’s interesting. When you first meet him, you can’t tell if he’s trying to express himself or come out of his shell or if he’s almost on that autistic spectrum.

Sheen: I used to not be able to talk about his secret of being abused as a kid. So for me the whole thing has been about how does abuse affect someone. How does being violently, physically abused by your own parent when you’re a kid, how does that affect your personality as you grow up? How does that make you defensive? And what does it take to break through that? And I didn’t want to do that in a shortcut or easy answer ways. Even though it’s a show that ostensibly is about sex, the show for me has always been about the journey of a man who is completely imprisoned by his past. And how does he slowly find his way out of that, even though he resists it. So when Virginia comes along, this woman who seems to call to something deep inside him, as he feels the pull towards that woman, he’s hitting up against everything that he has difficulty with, being intimate and honest and vulnerable and all those things that he’s defended against because of what happened to him as a kid. And so on the one hand he’s moving toward her and who he can really be, but on the other hand he’s fighting it. He doesn’t want to go there. So he both punishes her for what she makes him feel and goes toward her.

Odenkirk: None of what I asked you is applicable to me.

Sheen: Nothing.

Odenkirk: I got a phone call, do you want to play this character? He’s a sleazy lawyer, I can do that, I think. And then I find out that it’s really an intense drama, everybody’s playing it super intensely and quietly and deeply. And I show up and I’m having a good time doing it, and trying to modulate myself to the room I’m in, with Bryan Cranston and Aaron Paul and Anna Gunn. And then there’s Saul. He’s an asshole. But the Saul in “Breaking Bad” was a sleazy guy who’s trying to benefit himself.

Sheen: Were you intimidated going into that setup thinking, this is more straight drama, this is not what I’m known for doing?

Odenkirk: I wasn’t too intimidated. I probably should have been more intimidated. I did take it seriously, and I thought Saul was fun to play. But as they continued writing that character, they showed little glimpses of a human being. Just here and there.

Sheen: He always seemed like a real person. From the beginning you always totally believed this was a real man with a real life. I think one of the things that I always thought about “Breaking Bad” was for all its drama, it always had a kind of wryness about it. There was always a real strong vein of comedy, not out-and-out comedy but wry comedy, and Saul seems to embody that.

Odenkirk: There are episodes of “Breaking Bad” that are harrowing and frightening and then you watch them in a different mood and they’re hilarious. With “Saul,” it’s lighter in general and he’s a much more likable character. I didn’t know what they were going to do. I just trusted Vince Gilligan and Peter Gould.

Sheen: So you didn’t have anything to do with it?

Odenkirk: No, no, no. I didn’t help. One of the things that was great about “Breaking Bad” was really being an actor with a group of very serious performers and writers. I’m not a producer, I’m not the writer, I’m not a director. I have to just be this guy and immerse myself in his moment. And I don’t have to worry about any of the other stuff. I’ve had a lot where I’m the writer and an actor-director, and actor-writer-producer. So it was really a relief to just be able to play a part and commit myself to it. And I enjoyed immersing myself in it and challenging myself to do the lines exactly as written.

Sheen: Not to improvise?

Odenkirk: In comedy, you’re much more apt to go, “Can I just say this differently?” And people are like, “I don’t care as long as the intention’s there.” With “Breaking Bad” and certainly with “Saul,” everything is written. If you ask about a line, if you ask, why do I say “Good to see you” instead of just “Hello,” they’ll say, “Well, because …” They’ve thought through every word of everything. That’s kind of great. What’s been great has been to take these monologues and the lines, which are spoken not the way I speak, and figure out how to do them and try to make them natural. It’s called acting.

Sheen: Apparently.

Odenkirk: It’s new to me. But it’s a challenge. It is new to me to be like, “I’m going to say this exactly the way he’s saying, because I don’t talk like this.” He’s putting on a show, he’s distracting you with his words. Oftentimes I think the character is not really sure where he’s going. He’s just trying to keep the ball in the air until he figures out where he wants to put it. How to land with the person he’s talking to. He’s negotiating all the time. With “Better Call Saul,” even more than “Breaking Bad,” there’s an emotional hook, there’s a desire to everything you say. You’re always manipulating. Every single line. There isn’t a thing that’s tossed off.

Sheen: One of the dangers I’ve found with playing a character for a long period of time is that at a certain point, you start to feel like I’m the expert on this character now. When I first started, I didn’t really know this character well, and now I’m the expert. And if anything comes along in a script that doesn’t quite chime with what I think it should be like, my instinct is to go, no that’s not right, that doesn’t work. The danger is you don’t allow yourself to be surprised by your character anymore. People will go, “Well, Michael will know.” And you’ve got to allow yourself to be surprised, to try something different.

Odenkirk: The shows we’re doing, it’s a new era of TV. I’m sure that in “Matlock,” if Andy Griffith said, “Matlock wouldn’t say that,” he was probably right. Because the character was not changing.

Sheen: Exactly, yeah. In fact that’s the point, isn’t it? The point was the character should stay the same.

Odenkirk: I would not like that at all. We both have the same sort of question of, “Am I going to be able to be this guy for an extended period?” I’m so thankful they made Jimmy McGill a likable guy with drives and desires that I can really relate to. As long as they wanted to make this prequel, I was good with it, as long as it was an organic, genuine desire, which it was on the part of Vince Gilligan and Peter Gould. But I don’t feel like I know this guy. I don’t know where it’s going. People say, “Well, he’s going to be Saul Goodman.” But I say, not really. Saul Goodman was a front. He even told Walter White when he met him, “That’s not my name.” Look at his office, it’s a front. It’s a set. We don’t really know who he was during “Breaking Bad.” They did a scene after the “Breaking Bad” experience, and he’s working in a Cinnabon, and we see another iteration of who the guy is. So I don’t feel like I know him, I hope I never feel like I completely know him. He’s always discovering new things about himself and changing and that’s how I’ll get through doing hopefully years of the character.

Sheen: Even though you’re playing a fictional character, and I’m playing someone who’s based on a real person, having what actually happened in the real Bill Masters life there, people tend to think that that limits what you can do. But actually it helps because it makes me then go, how can you surprise? Even though we know the facts of what happened, what is surprising about that? How can you totally wrongfoot an audience into thinking they know what’s going to happen? I guess that’s similar, if you already have who Saul in quotation marks is in “Breaking Bad” looming ahead, you’d think that it’s limiting, but actually it’s not. It’s liberating. You never know who he is, he’s a constantly shifting thing. There’s what he appears to be and what he actually is underneath. I think that’s similar to my experience with Bill as well.

Odenkirk: What was the first role you got paid for?

Sheen: I left drama school a little bit early to do a play on the West End stage with Vanessa Redgrave. And that was my first paid job.

Odenkirk: All right, that’s a big deal.

Sheen: I remember I did have a moment where I suddenly realized this is a job, people are paying me to do this. And I had a little wobble then. I also had a wobble when I walked into the theater on the first day, and I was so excited to see my name up on the billboard outside. They were just finishing painting Martin Sheen’s name. I thought, should I tell them that my name’s not Martin Sheen? Maybe it will get more people in this way.

Odenkirk: Did you tell them?

Sheen: I did — eventually. I know you shoot “Saul” in Albuquerque. How did that impact you? Because we shoot in LA, and that is a big part of it for me.

Odenkirk: When we talked about “Better Call Saul,” before we did it, everyone talked about it as though it would be very much an ensemble show, like “Breaking Bad.” That’s what the guys had written most recently and it was just assumed when we discussed it that that’s what would end up happening. And if you’ve watched any of it, it’s not an ensemble show yet. I hope it becomes one. But I was in every scene for show after show, for two or three weeks at a time.

Sheen: That’s got to be different than “Breaking Bad” for you.

Odenkirk: My character talks a lot, some long monologues, so being in Albuquerque just allowed me to really concentrate and do the amount of work I needed to do. If I was home I don’t think I would have been any help to my wife and kids. I needed to go to work, come home and work until I fell asleep and then on weekends, it’s just prepping. Because these are scenes where you can’t show up and go, “OK, what am I saying? Show me the script.” You have to know a scene cold.

Sheen: I’m about to start shooting the next season of “Masters” now, and when we came to do the first season, because I didn’t know what to expect I was just happy-go-lucky, going into it. The second season I remember going into it and thinking that was quite hard work, that first season, and now the third season I know exactly what I’m anticipating. You’re working all day, you start very early in the morning, and then at night it’s just about learning lines for the next day. And then trying to get enough sleep so you’re not really tired the next day and you just prep on the weekend.

Odenkirk: It’s hard as hell. But it’s wonderful that you’re actually acting. That’s what your job is. It’s not to spit out lines and wear a costume that looks like the character, stand approximately in relation to another person you’re speaking to. You hear about movie stars who have a double for when there’s an over-the-shoulder shot. We’re getting complicated scenes and challenging moments. And finding out things about your character you didn’t know. Which is pretty great. I’m just hoping that in the second season this wonderful cast that we have can have some of the story spread out a little bit — and I can come home on a Friday night.