"I think we needed to see the character grow past Lindsay's character leaving," the actor tells THR about Jay's new love interest on the cop drama.

[Warning: This story contains spoilers from Wednesday's episode of Chicago P.D., "Care Under Fire."]

Chicago P.D.'s Det. Jay Halstead (Jesse Lee Soffer) is having a rough go of it to say the least.

After losing his longtime girlfriend and partner, Det. Erin Lindsay (Sophia Bush), at the beginning of season five, the cop and army veteran saw his PTSD come back in Wednesday's episode just as he went undercover to get close to a fellow former Army ranger who served at the same time as him. The man was brutally killed in front of Jay, only to further bring up his past demons from battle, and he also fell for the man's sister, Camila (Quantico's Anabelle Acosta). The episode ended with Jay consoling Camila as he lied to her face, both about his identity and about being there when her brother was killed.

"[He's] making some bad choices," Soffer tells THR about Wednesday's turn of events.

In the light of the revelations about Jay's demons and that unexpected ending, THR jumped on the phone with Soffer to discuss all that plus his research for Wednesday's episode, the "shift" in season five under new showrunner Rick Eid and Bush's exit.

We've known about Halstead's military background since the start of the show but why was now the right time to explore it to this extent? Why is his PTSD such a factor now?

Well, we never had fully explored it and I think this season, Rick and [executive producer/director] Eriq [La Salle] and our producers, they've created some new storylines and they're kind of doing these mini-movie episodes with characters every week where someone gets to really be highlighted and show where this person's at in their life, where they came from, stuff like that and it's been really fun.

Given you've been playing the character for five seasons now, did you get to give any input when it came to this big Halstead episode?

I actually don't get to have input about that stuff. (Laughs.) I give all the credit for this storyline to Rick and Eriq and everybody. I think probably they wanted to see Jay a little broken because his life's gone through shit. His partner's gone who was also his girlfriend for so many years and I think that they wanted to see him struggle. We've seen Jay struggle in situations but we've never seen him struggle internally and that was a new thing. They said, "Why not? Why not open him up to that now?" The first episode of the season where the little girl gets killed, he's found innocent of wrongdoing, however the emotional reality of what happened stays with him. That, along with not having anyone to rely on, it opens up this kind of Pandora's box into his past and things that he's had buried that he hasn't deal with. It's been a whole new character to play, really.

How did it make the character new for you? How did that inform you as an actor to see this other side of Jay?

It's kind of like you have this like laundry list of traits and characteristics and you know how you're going to react in certain situations. You understand the different dynamics you have with the other characters and the relationships, and then you just introduce one new idea and it changes each of those things on that laundry list a little bit. It gives it just a subtle shift that kind of takes over. It's been a really interesting experience to know a character so well and to have played him for so many years and then to get to change some things.

What kind of research did you do, particularly for those heavier scenes involving his PTSD?

I talked to a couple of people who have served and dealt with stuff like this before, and then you kind of put your own interpretation on things.

Did you feel extra pressure to act out those scenes after having talked to veterans?

Not pressure, but I would say a strong hope that you represent it accurately and bring some truth and honesty to it so that people feel well-represented. Really, the whole point is to connect. If viewers are watching and know someone who has dealt with or have dealt with it themselves and they can connect and see a character go through something and come out the other side. Or if they can connect and have a deeper understanding of something or of someone in their life, that's the goal I think for all of the entertainment business. I felt pressure to do that, I would say.

It seems clear at the end of the episode that Halstead is still dealing with PTSD and some other issues so how will that be reflected in future episodes?

I don't know how much more we're going to touch on the PTSD. There's also other characters to service and write for, so that might come back around, but what we do see is Jay lost. He's making decisions and making choices in his life that he would not have made previous to these experiences, and because of that, we see him really messing up and making some bad choices.

What can you say about his connection with Camila? What attracts him to her?

He's finding someone to connect with but it may be in the wrong place. And he's kind of going, 'Screw it, who cares what people think? Who cares what the right thing to do is or the wrong thing to do is? I'm just going to do what I want to do,' and that's not like him so that will be interesting.

This is his first love interest since Lindsay left so how will this relationship differ from that relationship?

Well, this relationship is a lie. She doesn't know who he really is, and he keeps up with the ruse of he's this guy [Ryan], who's really just a character he was playing when he was undercover. But I think he does care about this person and cares about her loss. And maybe he feels a little alive and not so alone again. He just goes, 'Screw it,' and we'll see where the chips fall.

There had been a lot of speculation about who Halstead's first post-Lindsay love interest would be and when that would happen. Why was now the right time?

I don’t know if it is the right time, I guess the fans will have to respond to that. They might think it’s the wrong time entirely. But I think we needed to see the character grow past Lindsay's character leaving. So much of who he was on the show was tied into her character and he needed a new coming-of-age story this season for sure to get past all of that. Really, this season is a series of trials and tribulations to see how he comes out the other side.

Given what you said about the Halstead and Lindsay characters, how did you feel coming in for season five knowing you wouldn’t be acting opposite Sophia anymore?

It was sad. It's hard. When someone leaves a show that was there from the beginning and we were a big family. It's kind of like doing a new show a little bit. It's like, what is it going to feel like now? What is the scene going to play like? What's my character going to be doing? … It's definitely been difficult but the show must go on.

The show also faced changes behind the scenes with Rick Eid replacing Matt Olmstead as showrunner. Was there a script or a scene or a conversation you had with Rick that really gave you confidence going into season five?

It was after getting that first script and going, "Whoa, we're really dealing with Halstead having killed a little girl. Yes, he was found to be doing it justly, he was vindicated, but it's a major heartbreaking story." It was like, "Whoa, OK, we're really going to deal with some stuff here."

And then there was another episode where Ruzek and Atwater have this great scene where Ruzek is trying to tell a guy to get on the ground and he's got a kid with him and he's black, and they're in a bad neighborhood and the guy doesn't want to do it. Ruzek says, "I'm going to shoot you." Atwater is trying to de-escalate the situation and says, ["It's not easy for a black man to get on his knees for a white cop."] It was like, whoa, we're actually dealing with some current events and current tensions and I think we're doing something that's important. When I read that, I thought, 'We've got our finger on the pulse. This is going to be good.'

Why do you think it was important to lean into those current events and current tensions?

That's what television should be. A show like ours, if you're trying to tell real-life cop stories, then let's tell real-life cop stories. What are the stories you see in the news? What are those stories people can connect with? If you're not doing that, it's just crime of the week or bad guy a. and bad guy b. What's really important about that? Let's have a discussion.

With Sophia's absence, you've also had to establish a new onscreen partnership with Tracy Spiridakos' character Upton. How has it been finding that rhythm?

It's been fun. She's great and she's a really good actor and she's awesome to have on set. She fit in right away. It's kind of self-explanatory, it's like, here's Jay, he's kind of alone and feeling a little broken in the world and they're kind of thrown together. She seems to be doing well, and he's really not doing well and he should be relying on her but he's not quick to trust and not quick to let her in. The results, I think, have been pretty good. We've had some really good scenes.

Upton makes it clear in this episode that she knows Jay is going through a hard time. How does this episode and his issues test their partnership?

I think going forward, he's going to have to rely on her a little more and trust her and let her in a little more about the issues that he's dealing with. Otherwise, he's going to lose her as a partner or he's going to lose his job. He's got an advocate and a friend who wants to help him and try and take care of him a little and he's going to have to let somebody in.

Speaking of, what can you say about how his working relationship with Voight (Jason Beghe) has changed this season?

I think Voight really respects Jay and Jay's kind of moving up on Hank's good side. They always butt heads about how to do police work but neither ever doubted the others' convictions or doubted that the other was a good cop. They had their differences but they always respected each other. Now with what's going on in Jay's life and the choices that he's making, he's got a really steep hill to climb with Voight on his way back from all this stuff because you can’t keep anything from Voight, you can't hide things form Voight. How that relationships looks in another month remains to be seen.

Chicago P.D. airs Wednesdays at 10 p.m. on NBC.