'Chicago Fire' Boss Previews "Fork in the Road" for Casey and Dawson (Exclusive Video)

"There are very concrete things that are pulling them apart from each other," says showrunner Matt Olmstead. Plus: Watch an exclusive clip from Tuesday's episode.
Courtesy of Elizabeth Morris/NBC

After three years of on-and-off romance for Casey (Jesse Spencer) and Dawson (Monica Raymund), season four of NBC's Chicago Fire has been a (somewhat) stable one for the couple. Although the beginning of the season brought Dawson's heartbreaking miscarriage, things have otherwise been relatively drama-free for the duo, who also began the season engaged but have been in no rush to tie the knot as of late.

"We've played every angle, every different way that relationship can go, forward, backwards, sideways between the two of them," showrunner Matt Olmstead tells The Hollywood Reporter. "We feel like we've had some success recently with not worrying about how to define it and letting them have their own storylines, but still having kind of a loose connection pinned to the two of them. They've been through so much  why worry about defining it right now?"

And they're about to face yet another hurdle as season four comes to a close. Now having won the alderman election, Casey's new position will complicate things. "As Casey starts to ascend a little bit here with, he just wants to be a regular Joe alderman, but there's someone who identifies him as possibly having some potential. Anybody's going to listen to those conversations as he is," Olmstead says of political consultant Susan Weller (Burn Notice's Lauren Stamile), who was introduced at the end of the most recent episode. "He's kind of wondering, 'Hmm, when I'm done with being a firefighter, is there another career beyond that?'"

As Casey begins to consider a new career, Dawson will begin to contemplate taking on a new title as well  that of mom  after she rescues a foster kid during a call.

"[She] does the one thing they advise you against doing, which is following up on the well-being of the people that you save on a call," Olmstead says. "So she becomes a little bit concerned with the well-being of this kid who is actually in need of somebody looking after him, so she plants her flag like, 'Why not me? I know there's a million reasons not to, but things happen for a reason.'"

Taking on such a big responsibility, and her decision not to consult Casey about it, will have repercussions.

"She is not asking him. And she's making it very clear: 'This doesn't involve you. It doesn't have to. This is my decision. This isn’t some kind of psychology move to test your commitment in the relationship,'" says Olmstead. "She wants to do this for very simple reasons: This kid needs help."

Dawson's sudden decision not only raises questions from Casey, but also from her brother, Antonio (Jon Seda). "Antonio has something to say, believe me," Olmstead says. But it's Casey, not Dawson, whom Antonio shares his feelings with  a scene which Olmstead was "enthusiastic" to include.

"So many times when those characters come together, it’s a lot of back slaps and high fives and hand shakes and thank yous," says Olmstead. "Antonio is such a good guy, this is the perfect time to have these two characters lock horns.

"So Antonio comes to Casey and really lights him up for what he perceives to be kind of not committing to his sister, letting her go off and do this thing," the showrunner continues. "There's risks involved and dangers involved. Something could go wrong. Who knows what the kid has been exposed to, or what the mom ingested during the pregnancy? Who knows what could happen? As opposed to yelling at his sister, he goes to Casey and holds him responsible and tells him to either commit or let her live her life."

So what does this mean for the future of Dawson and Casey's relationship? 

"They're really going two different directions," says Olmstead. "There are very concrete things that are pulling them apart from each other: His is a potential career beyond the firefighter, and hers is being a foster parent, which is obviously a big deal. By the end of the [season finale], we kind of define which way they're going to go. … This is really the fork in the road for these two characters."

The seeds of that conflict begin to pop up in Tuesday's episode, when Susan meets with Casey and Dawson to talk about Casey's political career. Watch The Hollywood Reporter's exclusive video of their sit-down below.

Chicago Fire airs Tuesdays at 10 p.m. ET/PT on NBC.