This Tuesday at 10/9c, CBS’ Person of Interest wraps its five-season run — but not before heaping upon Team Machine more loss during their final battle against Samaritan.

Already during the show’s 13-episode swan song, longtime frenemy Elias took one for the team he had just barely joined, while Root died a hero’s death by steering herself into the path of a bullet meant for The Machine’s creator, Harold. In the wake of that tragic loss, Finch has gone a bit rogue, securing and unleashing a computer megavirus capable of vanquishing Samaritan — as well as its kinder-hearted kin.

With one last, epic clash on the horizon, Michael Emerson spoke with TVLine about Harold’s “desperate” act, the final run’s more emotional moments and why he’s walking away from the show a tiny bit worse for the wear.

TVLINE | Why has Harold splintered off and gone rogue, and not invited the team along?

Because I think he feels like this is really a suicide mission now. Too many people have died already because of him. He doesn’t want any more casualties.

TVLINE | In what specific ways do you think Root’s death affected him and the decisions he’s now making?

I think it kind of rocked his world a bit. I supposes it’s a thing that he’s always understood in the abstract, but when [her fate] came to be, sitting there next to her and to have grown to have such a “family” feeling for this woman who four seasons ago kidnapped and tortured him! …. When people are on your side, you’re willing to forgive a lot, I think.

TVLINE | When it comes to deploying the Ice-9 virus, is putting The Machine’s livelihood at risk Harold’s second-worst nightmare?

Yes, I think so. The Ice-9 virus puts everything “cyber” at risk. The Machine is his creation, and part of him is just sick of himself for having handled things badly. Now he’s going to have to do something quite desperate to set things right.

TVLINE | What do you think he’d do differently, if he could do it over again?

He would have to sit down and think about that. He could have unfettered The Machine, but then that would be going against his character, and it would have created a thing that…. I mean, Samaritan wasn’t an “evil” code; it just does what artificial intelligences do. So when he looks at Samaritan, he sees what his machine would have been, uncontrolled.

TVLINE | You have a great scene with Jim Caviezel in the finale — a bit of it is in the trailer that’s out now — where Harold discloses how his relationship with John ultimately surprised him. Did that turn out to be one of your favorite moments from the series?

It is good. There are a lot of great moments in these final two or three episodes that finally make explicit things that we and the viewers have been feeling for a long time. It rings the chords of the “family” that they’ve made, finally saying it out loud.

TVLINE | As an actor, did it please you to see the show go there? Especially in a season where there wasn’t much time to pause and touch on such things?

Yes, because as we were shooting these final 13, I kept thinking, even as far along as Episode 9 or 10, “Where’s the ending? What form will it take?” So it’s nice to see that they were able to “put the brakes on,” turn around and do something surprising and satisfying in the last few heartbeats of the series.

TVLINE | Even that conversation between Harold and Root in the car, during a high-speed chase and with guns a-blazing…. What they were saying was tremendously important.

It was. It was. Their conversation has always been philosophically crucial to the show and to the thinking of the writers. Whatever agenda, social or scientific or political, that our writers might have, that was the conversation that they spent the most time on, and the most care.

TVLINE | Harold/Root was almost like Jack Shephard/John Locke, that ongoing faith-versus-science debate.

Yes. Yes, it was.

TVLINE | Without naming names, obviously not everyone makes it out of the finale alive. Do you agree with the loss the team sustained in the name of doing the right thing?

You have to have casualties to give it gravity. That’s the only way that writers can say that these things have consequences, that these decisions have cost. To tell you the truth, I’m not sure who’s left standing, unitl I see it [Tuesday] night. But I’m always the one that has a bunch of questions after I see a finished episode, like, “Is that what that means?” Sometimes I have to replay them just to make sure that I’m getting what they’re putting out there! I had read the [series finale] script of course and acted in the scenes, but things change a little bit when they get cut and music is added, and they highlight the things they want highlighted and bury the things they want buried. That’s one of the interesting aspects of the job and one of the reasons why I always watch the finished episodes.

TVLINE | What’s your biggest takeaway from the Person of Interest experience? I mean, this is your second series in a row to have banked 100-plus episodes.

That’s right, that’s unusual. I’m really a lucky actor to have had two good shows like that, both of which I was proud of. My takeaway is: It’s hard to do a big show like [POI or Lost]. Both were huge to shoot, technically, with action and explosions and effects and all of that. I don’t know how much longer the network formula can support work that difficult, on the model that they’re using now. To shoot a credible half-of-an-action feature every eight working days…? I think it’s just unsupportable.

TVLINE | And worse, you have to limp through all of those action scenes!

Well yeah, and I thought I was so clever — “Oh, I will [affect] an infirmity, with no wear and tear on my body!” So guess who’s got physical therapy now for a stiff neck? A stiff neck that was a fictional stiff neck for five years, and now it’s a real stiff neck! [Laughs]

TVLINE | Hugh Laurie has joked about his knees going bad because of his House limp.

I wouldn’t doubt it. You end up favoring one leg over a lot of time. And I tell you, it’s not so bad with the day-to-day for any of those shows, but when Finch has to run for his life, through the streets of Chinatown…? That is so bad on the leg you’re using to support you. [Laughs] And we never get those scenes in one take!

TVLINE | You’re available again, and I think Terry O’Quinn is available now…? I know your pilot Odd Jobs didn’t pan out, but might you two finally get together for a new show?

We’re always talking about stuff, but I think he’s just about to begin shooting that [Amazon] series Patriot, where he plays the paterfamilias of this wacky, crooked political family. But I think they’d only do 10 episodes, because they’re sensible. If they said to me, “We want Person of Interest to keep going but we’re only going to do 10 or 12 [episodes],” I’d say, “Sign me up.” But I can’t do 22 again. I think people always expect me to be broken up about things coming to an end, but we were so tired in December, I couldn’t even have imagined coming back after the new year and shooting more.

TVLINE | Do you care where you work next? New York City versus L.A.?

I don’t care as long as it’s in the lower 48 [states]. One of the POI writers has written a pilot that will be shot and produced in Nova Scotia, if it goes. And I thought, “I’m too old to do that.” I can’t go live in another country. I’m supposed to audition for a part in a miniseries that shoots in Prague for months, and I thought, “I’m not sure I want to do that.” I know it’s a charming city and my ancestors came from there, but I don’t like living out of a suitcase like I once did!