Chicago Fire’s Derek Haas tells story behind latest One Chicago crossover

CHICAGO FIRE -- "Off The Grid" Episode 815 -- Pictured: Taylor Kinney as Kelly Severide -- (Photo by: Adrian Burrows/NBC)
CHICAGO FIRE -- "Off The Grid" Episode 815 -- Pictured: Taylor Kinney as Kelly Severide -- (Photo by: Adrian Burrows/NBC) /

Chicago Fire showrunner Derek Haas reveals the backstory of this week’s Chicago PD crossover and answers one of fans’ biggest questions.

Fans of Chicago Fire and Chicago PD are excited for Wednesday’s two-show crossover event, and so is Chicago Fire executive producer Derek Haas.

He connected with One Chicago Center ahead of the big night to discuss what you don’t know about the crossover, answer the question that several fans have asked since it was announced, and tell us which character he’d like to bring back in the next crossover if given the chance.

Learn more about the latest crossover in our Derek Haas interview below, then make sure you’re tuned into NBC from 9-11 p.m. ET/PT this Wednesday to see the two-hour event!

One Chicago Center: Can you explain the genesis of this particular crossover? It actually wasn’t the original plan?

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Derek Haas: We were talking about doing this as the original idea for the three-hour [crossover]. We were going to do Roman comes back in the summer, and then scheduling messed us up. And we had the idea for doing “Infection” and we were like, oh that would be gigantic. So we were going to do a version of this story as the original crossover, and we had to wait for Brian Geraghty’s schedule to open up for us, because he’s a very busy person.

It’s so funny, because you want it to be a reveal in the episode. When my family watched it, they didn’t know he was coming back, so I got to watch the surprise on their faces. But then of course you have to promote the show, and so most of our viewers know Roman’s coming back now. I wish those kinds of things could be surprises, but it’s impossible.

OCC: Brian’s character Roman works closely with Kelly Severide (Taylor Kinney) in the Chicago Fire episode, and NBC’s synopsis calls him an “old friend.” But how would you characterize the relationship? Because they weren’t especially close when Roman was on Chicago PD.

DH: They were on separate shows, but they’re cut from the same cloth. I remember when we were breaking the [Roman] character—back when it was [Matt] Olmstead and [Michael] Brandt and I doing PD—we were like, we need a Severide type on PD. That was kind of the genesis of Roman.

So in my mind, even if you didn’t see their relationship on previous episodes of Fire and PD, they would’ve been at Molly’s [together], run around with the same crowd. So they knew each other ahead of time, but it’s not particularly close.

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OCC: You’ve developed a system of doing a three-show crossover in the fall and then a two-show one in the spring. Why continue to go that route and not always involve all three One Chicago shows?

DH: It really takes up three separate schedules when you do the three-hour crossovers, because we have to stagger the productions. When we shot [“Infection”] last year, it was our fourth, [Chicago Med‘s] fifth and then PD‘s sixth. And you’re always sending cast over to them and it’s just a big jumble. So we’ve kind of just said as a group, we’re going to do a three-episode once a year and we’ll do a two-episode one the second time.

But the reason why it’s Fire and PD is so we can keep this shows in the order that NBC schedules them. If we flipped [time slots] and it was Fire, Med, PD, maybe it would be a Med/PD crossover.

OCC: As it specifically relates to Chicago Fire, you continue the Sylvie Brett (Kara Killmer) story in this episode, too. What’s going to happen with that subplot?

DH: Her birth mother reached out to her and in this episode we’re going to continue that story. She got an address and she got a name, and it’s not that far. It’s in the northeast corner of Illinois, a couple hours’ drive. So she’s going to go and explore further. But it wouldn’t be Chicago Fire if it all worked out exactly as you think it’s going to go.

OCC: Fans are excited to see Brian Geraghty back, so if scheduling was no object, is there any other One Chicago character that you would like to have guest star in something like this in the future?

DH: I have so many. It’s a real fondness for me to reach back into this now eight-season wellspring and pull old characters back. We had this Gorsch sighting. We had a Hope sighting. I’m always into the villain; love bringing all of those characters back. Gabby came back for one episode this year. You’re going to get to see Donna, who we haven’t seen in a while.

I would love for Mills to come back at some point. I’d always take another Otis sighting, whether it’s flashback or on a video or however we do it. Same with Shay. I’d love to have Antonio. [Jon Seda]’s one of my favorites that we’ve ever worked with.

Man, I can’t even think of all of the characters I’d like to see again. You never know who we’re going to bring back. And I do like bringing back first season-characters. You kind of reward the long-term fans, and our mission on those stories is that the stories work whether you knew the history or not, but it just adds a level of richness when you have been watching.

OCC: What else do you want fans to know about this upcoming crossover?

DH: I really love the way it turned out. You kind of don’t know, because Rick Eid’s in charge of PD and I’m in charge of Fire, and so you’re kind of saying, “Okay, here’s half a story and then I’ll put this into your guys’ hands.” So some of it is just crossing your fingers and getting the tone right and all of that. Their half of the show turned out really remarkable. So I’m very happy with it as far as plot points go.

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