Michael McKean stars in “Better Call Saul” as Jimmy’s older brother, Chuck, a far more successful lawyer who’s coping with an as-yet-unnamed condition that has limited his ability to lead a normal life.

Did you enjoy filming “Better Call Saul”?

It was a great experience — hard work, long days, 15 hours in the desert but well-worth it. I had a wonderful time working with Vince again. He and Frank Spotnitz created a character for me for “The X Files” that I did for a string of shows. I’m glad we’re together again, as they say in the business. But I haven’t seen a frame of “Saul.” I don’t like to see it until it’s too late.

Why did you sign on for “Saul”?

I’m a big fan of Bob Odenkirk. I’d encountered him a few times after he was at “Saturday Night Live.” I thought he was brilliant and funny. I was a huge “Mr. Show” fan. And I thought his Saul Goodman in “Breaking Bad,” which of course I watched like everyone else in America, was a fabulous character. So when the chance to be his big brother came along, I thought OK, I know how to do that. I’ve been a big brother.

What is Chuck’s relationship with Jimmy?

Chuck is definitely the grown-up. He’s quite a bit older than Jimmy. I’m tremendously successful. He’s the screw-up, the black sheep. But we love each other with the arms-length thing — that thing when someone you’re close to is also the person who has some power over you by virtue of his own success. The roles are reversed to a certain extent because he’s helping me cope with a dire situation I’m in — physical, emotional problems dealing with the world. Suffice it to say, that it is a real character with a real problem, and it was really, really fun to play. I’ve often played very intelligent people who are horrible and screw up everyone’s lives, and I’ve played benign dumbbells. This is a guy when we meet him who’s being crushed by the world, but he’s also a good man. Jimmy’s the bad guy, Chuck is the good guy. That’s a very important trigger for this show.

How does this show compare to “Breaking Bad”?

This is a show about the law, where “Breaking Bad” was a show about crime and the lives of those whose stories hinge on those crimes. This is similar in one sense that it really is about making choices and trying to avoid the disastrous ones while still serving your needs and those of the people you care about. But I have not seen a single episode of “Better Call Saul” and I’ve seen every episode of “Breaking Bad,” so I can’t compare them as a viewing experience.

Can you give any hints about your mysterious affliction?

If you’re smart, you’ll pick up on it right away. You might not be aware of anything like this but it’s a genuine thing. Everyone will put it together after a couple of episodes. After maybe episode three, it is kind of spoken out loud. After the first three, all the clues are there.

You filmed this show while you were still on Broadway. How did you balance the two?

My friend said, if you want to hear an actor complain, give him a job! (Laughs.) I missed about five shows altogether. Then I read the pilot script as I went in to shoot the first episode. I got the rest (of the scripts) one by one, which really worked out well. I’m a man who’s trying to figure out his own mysteries. And it really helped not knowing where the hell they were taking me. It was kind of like dinner with a mystery.

Are you happy with how the mystery ended?

Well, it didn’t end. We just did one season, and we’re going to come back with another one. But where we ended it is a very interesting place. It’s that man who saves the world — and loses his soul.

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