'Chicago Fire' Boss on That "Dignified" Exit and the "Firecracker" New Addition

"We try to honor what really goes on in a firehouse, and there is turnover," showrunner Matt Olmstead tells THR.

[Warning: Spoilers ahead if you haven't seen Tuesday's episode of Chicago Firetitled "You Know Where to Find Me."]

Chicago Fire said goodbye to another series regular Tuesday in a sentimental and surprisingly bloodless sendoff. After biding his time as a paramedic for most of the season, Mills (Charlie Barnett) finally got the clearance to return to squad, and then promptly left Firehouse 51 altogether to open a restaurant in North Carolina with his mother and sister.

"You're picking between two families in a way: Your family at the firehouse and your real family," says Chicago Fire showrunner Matt Olmstead. "He opted to now be with, and succeed with, his real family."

The Hollywood Reporter spoke with Olmstead about the decision behind Mills' departure, why he didn't die, Brett's "firecracker" of a new partner and the finale that will divide the firehouse.

What was the reasoning behind this exit?

It wasn't specific to the Mills character or Charlie the actor. It was a general sense of looking at the show and what kind of new stories we could bring in, new blood we could bring in, which we do somewhat vigilantly throughout the season each season. As much as we can, we try to honor what really goes on in a firehouse, and there is turnover, and it can be somewhat wrenching in that they work together 24 hours at a time and become a family, and you never want to see someone go. You can get emotion and conflict out of that.

Looking at the journey of the Mills character, the first time we saw him he's walking up the driveway headed towards the firehouse. He's a brand new candidate, and we took the character through all these things in terms of going from that to truck to squad and romances and revelations about the family. We were always very appreciative of what Charlie brought and what the character brought to the show, But, again, it's just looking at the board in terms of how can we continue to reinvigorate the show and keep it going. … We fix as we go along and try and add fuel as we go along.

A lot of times, people leave in Chicago Fire in body bags. Was there ever a discussion about killing off Mills?

There was a big discussion about how he would leave, but we would never entertain the idea of killing the character off. We always knew from the beginning — once this idea started to get some traction — that we wanted a dignified departure for the character because that obviously leaves the door open down the road. But first and foremost, we wanted him to complete his journey. He came into the firehouse chasing the legacy of his dad who he didn’t really know that well, and on the other side of him, is the mom's side, where they ran the restaurant and where he worked. He's close with his mom. He's close with his sister. His dad's been gone for a long time, so he's the man of the family. So we always played that polarity of firehouse and restaurant — the two sides of his life that he had always struggled to reconcile. … There's this realization that — you know what? — I think I've fulfilled the goal that I had in terms of finding out who my dad was and honoring what he did by becoming what he was, and now's the time for the next adventure in my life.

You've said goodbye to two series regulars in one season. Was there ever a concern or a thought to push this off to the beginning of next season?

There never was. To survive in today's marketplace, in my humble opinion, you have to really pull up storylines. You have to go through and be ambitious, and you have to get people leaning forward. There are just so many choices out there. We're not trying to mimic other shows like Game of Thrones (laughs). We're not trying to kill off the whole cast, but you also don't want to get complacent, and you don’t want to get to the point where you don’t want to let an actor go, so let's just keep everybody. Then all of a sudden you get the call that your show's no longer on the air because it got flat. You have to be objective, and you have to be vigilant storytelling-wise.

April departed in Tuesday’s episode to travel around the world, so does this mean viewers have seen the last of her? Will she still be a part of the Chicago Med team going forward?

If Chicago Med goes, we'd see more of her.

Has there been talk about kind of a character you want to see paired with Brett as the other paramedic on the show?

For sure, and we've already filmed a couple episodes with that actress. Having seen those episodes, it's exactly what we had hoped for in terms of a breath of fresh air. One of the things you realize is when you start to look at an episode or a season is you have to pair heavy storylines with lighter storylines. As created by Derek [Haas] and Michael [Brandt], this show is about a family that likes working together. It's not about people who hate their job. It's not a dark show. Sometimes there are dark things that happen, but they come together as a family.

What can you say about the dynamic between Brett and this character? How are they alike? How are they different?

They like each other but there's a big difference in that Brett is still a small town girl who is in the big city for the first time and who is getting her feet under her. Here comes a girl who has more life experience. She's from Chicago so she lives a little faster. So Brett is paired with someone who's a firecracker. … In the first episode, there's a feeling out period in terms of finding out 'what common ground do we have other than the fact that we work together?' It's someone who's shot out of a cannon when they come in, and Brett dealing with that energy.

Obviously there are a lot of in-house romances on the show. Are there any plans down the line for this new character and anyone else from Firehouse 51 — or maybe even someone from Chicago PD?

Absolutely. We don’t have anything planned as of yet, but we know that that is available to us, which is another thing about bringing in new characters. Sometimes a lot of men are on firehouse and then we have Dawson who's already dated three different people in the universe of both shows. You do need to have some people who are available to date on a most basic level. Bringing in somebody who is single gives us opportunities. And then one of the endings of the finale is a hookup between a character from Fire and a character from PD. Not Severide and Lindsay.

What else can you say about the Fire finale?

The house is really divided because Severide brought in his friend, the Rice character, and there starts to be some whispers that turn into grumblings which turn into overt accusations about Rice being what's called a "ducker," which is somebody who, as a firefighter, isn't the first through the door and finds a way to stay out of the heavier aspects of the job. Those accusations are denied, and it becomes truck against squad and ultimately, its Severide against Casey. Severide is defending his guy, and Casey is defending his guy who's making the accusations, Otis. It's a revisit to the beginning of the show when Severide and Casey were divided over what he thought were mistakes that the other made that led to the death of their friend, Darden. The house is really divided, and it ultimately all lands on the Rice character — whether he did what's he being accused of doing and what he's going to do about. That's one of the main things that goes on that is resolved in the finale.

The other thing is we've played a couple of episodes of the Casey character working at a remodel of a strip club. … He slowly is drawn into that world, backs out and is approached by Voight to go back in. For us, it's the long-awaited conflict, confrontation, collaboration between Voight and Casey. By design, we've never had them cross at all on the two shows because Casey never forgave Voight for what he did. When Voight needs him to go back in to work at the strip club because they're convinced that there's some shady stuff going on over there, Casey ultimately does the right thing and goes in there, and it leads to one of our main cliffhangers. They underestimate the magnitude of what's going on there, and Casey bears the brunt of it. And then it's also the Casey-Dawson romance. It becomes decision time for those two in a big way.

Chicago Fire airs Tuesdays at 10 p.m. on NBC.