Jonathan Banks has had a long, varied career, but he's never had a better role. He's done drama. He's done comedy. He's played good guys (most notably as FBI Agent Frank McPike on "Wiseguy") and heavies. But he's never had a role as nuanced, as memorable, as his gig on "Breaking Bad" as cop-turned-fixer Mike Ehrmantraut.

(Spoilers coming up immediately if you haven't seen this week's episode.)

It's a job that Banks says was "as good as it gets" for his 45-year career, and it's one that came to an end with Sunday's episode. The DEA finally got the dirt on Mike — and for the second time this season, got their hands on money he had intended for his granddaughter Kaylee — and Mike, on the run, asked Walter White to bring him his go bag, only to be shot to death by the gun in that bag.

I spoke with a cheerful, philosophical Banks about the start and end of this role of a lifetime, what motivated Mike, and more.

Hi Jonathan, how are you?

Jonathan Banks: (pleasantly) I'm old and bitter. And yourself?

Are you bitter about losing the job?

Jonathan Banks: (laughs) I'm bitter. There's a whole smorgasbord of things to be bitter about. Actually, there's a beautiful California sun coming up in front of me, so I really have nothing to be bitter about.

How did you react to Vince telling you that Mike was going to go?

Jonathan Banks: "Motherfucker? What are you out of your fucking mind?" No. I kinda knew I was going to die. I just kept thinking I was going to die at some point. I would say it to my wife. it didn't come as a big surprise. Vince gave me the courtesy of telling me nine months in advance.

Knowing that, did it affect your performance at all?

Jonathan Banks: I don't see how it could help but not. You go in. You try to concentrate on the work, but at the same time, there's a certain morose wistfulness about the whole thing. I just loved Mike. I loved playing Mike. He was just a great, great character. Vince gave me such a gift. I keep using that word, but I really do feel that way. When you get a character like that, and you get to bring whatever years and ability that I have to fill it out, it was just a wonderful experience

There was a point in the previous season where Mike was coughing a lot, and usually there's no such thing as an accidental cough in TV, which led some people to speculate that Walt wasn't the only character with cancer.

Jonathan Banks: I don't remember why I was doing that. I may very well have had a cold. There was no intention, no talk of me ever being sick.

Vince has talked about how Gus's role only expanded because they had to get rid of the Cousins earlier than planned, so I have to assume that Mike also grew much more prominent than you knew when you took the job. What did you know at the time you got it? What were your expectations?

Jonathan Banks: As I understand it, Bob Odenkirk had a conflict. He was supposed to be the one who was going to clean up the girlfriend's death, and he had a conflict, so they had to bring in someone else — a cleaner. And they liked what I did. I went in there, I'd never seen the show, and I thought, "I'll go in here, I'll guest star and I'll be gone." It didn't turn out that way.

So when did you realize how special this character was becoming?

Jonathan Banks: Not until the half-measures speech at the end of the third season. I really got to do something. Until then, I was fiddling around with gadgets, and dealing with stuff. And all of a sudden, I thought, "That was pretty cool."

What did you like about Mike?

Jonathan Banks: I love Mike's code, and beneath that, I think, and I brought to this, that Mike had lost his soul a long time ago, and he knows it. I tried to never dumb Mike down. And Mike will never forgive himself for the things he had done or the things that he does. The death in the end, that was maybe the easiest part of his later life — the death was the peace. It was finally peace. The only touch he had anymore with normalcy was his granddaughter, who he loved. And I've always said, you've never seen it on the screen, but — when we were shooting the episode where I go to the warehouse and shoot it out with those guys — I said to Vince in the scene where I drop off my granddaughter, and there's a woman at the edge of the frame who's waiting for us, "That may be her mother, but that's not my daughter." Part of my actor's thing, part of Mike's sadness and tragedy, is that something has gone wrong with his son somewhere sometime.

When Hank and Gomez interrogate Mike this season, they allude to some terrible event that ended his police career. Do you have any thoughts on what that might have been?

Jonathan Banks: I kind of have a grab bag of stuff. I'm not really ready to say it at this point, because I still haven't decided, quite honestly.

You said before that death brought Mike peace? Do you think he was looking to die when he agreed to let Walt bring him the bag? Or was it entirely that he wanted to keep Jesse safe?

Jonathan Banks: I think Mike was trying to keep Jesse safe. I think he definitely sees good in Jesse and wants to protect him. As far as Mike letting his guard down so often this season, it's when I don't shoot Lydia in the head — if anybody had seen the half-measure speech, they're screaming at the television, "It's a half-measure, Mike! It's a half-measure." I will say again, the writers have given me this wonderful character, but whatever loopholes I might see in it, I am at the mercy of the pen. I am at the mercy of what they write.

So in your mind, do you think Mike would have let Walt bring him the bag?

Jonathan Banks: I think he would have allowed Walter to bring him the bag, but he would have made damn sure he was armed when they had any kind of conversation.

What was the atmosphere on the set like the day of your death scene?

Jonathan Banks: The crew all wore black armbands. There were a lot of tears. I loved my crew. I've done this professionally for 45 years, and this was as good as it gets. The actors loved the crew, the crew loved the actors, the producers, the writers — we were all in it together. Even the publicity people at AMC — I don't know if Olivia (Dupuis, the AMC publicist who had connected our call) is still listening at this point — but how good they were to me, and to us. Without sounding totally maudlin and sappy, it was just a hell of an experience, and a wonderful time.

Alan Sepinwall may be reached at sepinwall@hitfix.com