Nick Gehlfuss Previews Will Halstead’s ‘Heroic’ Return (Exclusive)

Chicago Med is celebrating its milestone 200th episode by bringing back one of its original cast members.

Nick Gehlfuss returns to the hit NBC medical drama as Dr. Will Halstead in the Oct. 8 episode — and “it is quite the heroic entrance,” he tells PEOPLE.

When the actor, 40, left the show in the season 8 finale in May 2023, Halstead moved to Seattle to be closer to his longtime on-off love, Dr. Natalie Manning (Torrey DeVitto), and her son, Owen, who was born in season 1. More than two years later, though, it seems they may be struggling.

“We think he’s going to live happily ever after,” Gehlfuss says, “but he’s still having his hurdles with Natalie. I think his efforts to figure out this family dynamic and being a father is really at the helm of his day-to-day.”

Below, Gehlfuss previews Halstead’s reaction to his ex Dr. Hannah Asher’s (Jessy Schram) pregnancy and the identity of her baby daddy, his early impressions of new docs John Frost (Darren Barnett) and Caitlin Lenox (Sarah Ramos), and his reunion with Dr. Daniel Charles (Oliver Platt) and Sharon Goodwin (S. Epatha Merkerson).

PEOPLE: How did this return come about?

NICK GEHLFUSS: Allen MacDonald, the new showrunner, called me and asked if I was interested in coming back, and it really happened to be the perfect time. We talked over the phone first, and I quickly realized we were on the same page. It was fun being a part of the creative side with them and figuring out something different for Will.

What was that first day back like for you?

You know when you have a memory, or you see an object or a smell that transports you immediately back to a time? I had hundreds of objects and humans and smells and just images, and it was overwhelming in a way, but just all good. The set had changed in ways I didn’t know.

They gave a round of applause and it was moving, and it was just all a wonderful reunion with a fantastic group bunch of people that I knew for nearly a decade and hadn’t seen for a couple of years, but then a great group of newbies as far as crew and cast. And I quickly began to realize that, “Oh, this show has changed and enhanced itself, and it’s now their show.” And I’m very proud of it. The show is in good health, and I’m always going to be invested in its wellbeing. 

You mentioned the newbies. How was working with Sarah and Darren?

My first scene is with Darren, and it is a frosty collision. What they did was really so creative. Allen said he wanted to pay homage to the first episode of Chicago Med by having some callback moments, and season 1 starts off with the Connor [Colin Donnell] and Will alpha-male “Who’s this guy?” moment. With Frost and Will, it becomes the reverse. It’s just terrific the way they bump heads. I also think it’s such a fantastic set of circumstances for Will because he’s really trying to figure out his family unit back in Seattle. 

So how are things going with Natalie and Owen in Seattle?

I think everything was probably going very well until a few months ago, but some changes have occurred, and he’s trying to figure out his relationship with Owen. The tension around that relationship is obviously affecting him and Natalie. And so, he’s set off to Chicago, I think, to figure out his new home in a way, and he is going to have a bonding boys weekend with Owen.

Allen did tell PEOPLE that your visit to the hospital is with Owen in tow and that you were going to a Bears game.

Yes, and it is quite the heroic entrance, I must say. It was very fun to play it. Will is thrust back into his workplace, and he falls right back into habits and his ways, and is quickly put into his place.

Well, when you say, “his old ways,” Halstead’s habits weren’t all good.

Correct. Not all his ways. He doesn’t have that type of control anymore, of course. And before he’s able to try and grasp that type of control, Goodwin puts him in his place quickly. But I think we’ll come to see that with Will’s relationship with Owen, he is trying to figure out where he can have control elsewhere.

How does Halstead react to the news of Hannah being pregnant and who the baby daddy is?

Oh, he certainly makes it known to Hannah, right to her face, and very early on. There’s a lot of great Hannah and Will stuff that’s to come within these episodes. The fans of the relationships will be very satisfied. It gets so awkward and tense at moments but people will be very happy with elements of some of the relationship stuff we are exploring. It gets pretty emotional in a beautiful way.

Did Allen tell you that he was considering you as a potential baby daddy?

He did. I think they probably went in the right direction with that. Manstead fans would not have been happy. 

Chicago Med airs Wednesday at 8 p.m. ET/PT on NBC.