Welcome back to Gaffney, Dr. Will Halstead! Nick Gehlfuss returns to Chicago Med for its 200th episode, airing on Wednesday, October 8, and in some ways, it sounds like it will be like he never left … even though he’s not supposed to be working there as a doctor. (But he’s Will — it’s what we love about him.)

The milestone episode is just the first of a multi-episode arc — Gehlfuss can’t give an exact number — as Will comes to Chicago with Natalie’s (Torrey DeVitto) son for a Bears game and, of course, ends up tangled up in the medicine and drama of his former workplace.

Below, Nick Gehlfuss previews Will’s return.

How has life been treating Will since he left?

Nick Gehlfuss: I think Will has had some struggles figuring out how to bond with Owen. And the reason I’m being a little cryptic on that is because some things will present themselves as why that is the case. So, Will is coming to Chicago Med with Owen to have a bit of a bonding experience, a boys’ weekend. That quickly turns wild.

As things do on Chicago Med.

Yeah, it has to.

So because of that, we know that he and Natalie are still together. What can you say about their relationship and how that’s been going?

I think it’s been going great ‘till they figure out this — yes, Natalie and Will have, obviously, they’re living together now and it’s bliss, but this rift that’s coming into play with Owen and Will is making their relationship tense at the moment.

Why do you think they’re able to make it work now? Because they never could when they were in Chicago.

I don’t think they’re working at the same hospital, although this is all TBD, but maybe not working together is helping that.

So the good thing is we’re going to see Will reunited with Sharon (S. Epatha Merkerson), with Charles (Oliver Platt), and with Asher (Jessy Schram), which should be very interesting. What can you say about those reunions?

It was a wonderful reunion and what’s so special about this return is that it is the 200th episode. The premiere is the 199th episode of Chicago Med, which is just wild to say out loud. I just think it’s such a special return and I thank the showrunner Allen MacDonald so much for crafting such a beautiful, a wonderfully emotional story with the writers and bringing me back at this just milestone of a moment. And the reunion is mixed as far as what’s happening on the episode.

But I feel like Sharon must be happy to see Will not working for her especially, right?

You know, you’d have to ask her, but of course, Will’s coming back in and he can’t just not stay a doctor while he’s at his old work. It’s a wonderful circumstance that has him falling back into his old ways when he’s not supposed to.

George Burns Jr/NBC

How hard is that for him to not just walk through those doors and immediately get into that swing of things?

I think for anybody, you can understand, eight years — I mean I was on the show for eight years, but we’re meant to believe he’s been there a lot longer and those habits are deep and I felt so much so that when I returned as an actor, we just fell right back into a working rhythm with everybody there. And while it was a wonderful reunion of a bunch of people I hadn’t seen in two years, I met a lot of great people as well who are new to the crew, new to the cast, that are carrying on this show as their own now and making it their own. And it’s great. The show is in good health, I would say.

How much are we going to get of Will and Asher? They had a past relationship, now she’s pregnant, the premiere revealed Archer’s the father. Are we going to get some fun conversations about all that drama?

Oh, yeah. It’s going to get very awkward and tense and I can’t go into more than that, but rest assured relationship drama will be on high and it will get emotional too as well. So have those Kleenex boxes ready.

How much is Will a part of that and how much is he more so observing it?

Oh, he’s right smack dab in the middle, I’d say. I’m sorry I have to be so vague, but fans will be satisfied with this story, I will tell you.

With whom does he have the most significant conversation in Episode 200?

I think Hannah is up there, and Dr. Frost [Darren Barnet].

Speaking of, Allen told me that Will and Frost get off on the wrong foot because Will involves himself in a case even though he is not wearing a lab coat. What can you preview about that dynamic?

Yes, well, Will is falling back into his old ways and it’s certainly a frosty start for him and Frost and there’s a bit of a competition right out the gate. And I think Will’s actually not maliciously so, but just tunnel-focused once again for a patient. And it’s quite an entrance into the hospital, let’s just say that.

It’s just Will being Will, it’s what we love about him.

Well it’s quite a heroic entrance.

Interesting. That makes me think of the first episode starting off with the train derailment and then Connor (Colin Donnell) entering and Will getting a look at him. Is that kind of like that? (Note: This interview was conducted prior to the Episode 200 promo being released.) 

That is very, very good observation. Allen MacDonald said he wanted to, this being the 200th episode, make it special and have some callbacks that mirrored the beginning of the show. Good job.

Will’s on the other end of that then this time?

Completely. Yeah, that’s well put. And I think fans will enjoy that.

George Burns Jr/NBC

Allen also mentioned Will’s dynamic with Lenox (Sarah Ramos) is going to be fun to watch?

Oh, yeah. Well Allen always wanted someone to knock Lenox off of her game a little bit or stir her a little and he said Halstead would always be the person to do that. So yeah, it’s good. We don’t get too deep into that but certainly Lenox appreciates Halstead for who he is by the first scene I’d say.

We know that you’re back from multiple episodes. What can you say about what’s keeping Will around in Chicago?

How do I put this? Guilt. Guilt is keeping him in Chicago.

Ooh, that’s a good tease.

And emergency.

What does Will think of all the changes at Gaffney since he’s left?

You know, we don’t get too deep into all of that, but I don’t think — we’re certainly not exploring the fact that he’s looking around saying that this is not changed for the better. I think he understands. I think he’s just coming to terms with the fact that he’s wrapped up in this world again and he doesn’t have as much control over it as he once did.

Is it going to be hard for him to leave?

I don’t know.

How much is Will in touch with his former colleagues, both those still at Gaffney and those not? How much are we hearing about that?

I would say that that’s not necessarily the forefront of this storyline. … I would imagine he is in family mode and we’re led to believe that they haven’t been in touch in a while, I’d say.

How is his career going back in Seattle?

As far as I know, great. There’s nothing in this storyline that would lead us to believe he is having any troubles with his career in Seattle.

How has it been stepping back into his shoes?

A blast, a joy, a gift. I am very lucky I feel like that this happened, that I was able to come back for such a milestone. I mean, how many shows get to this point? And while I did leave a couple years ago, I couldn’t have asked for a better return.

Allen told me that when he was looking at bringing back an OG, he specifically wanted to get you. What was that call like?

I welcomed it as soon as I heard that they had ideas and I said, of total interest. And then I met Allen in Chicago and we had a fantastic meeting and I knew we were going to be on the same page no matter what happened. And so it was just a matter of making the dates work and it was supposed to happen a while back. Fans might remember Sharon Goodwin saying, “Who next is going to come in here? Will Halstead?” I think she was recovering from her stab wound and that wild and crazy encounter. What a fantastic storyline that was. But she says — or was it, “Is Dr. Halstead going to come back?” Was that the line? I can’t remember. I can’t remember if that was the exact story, but she says that line after Dr. Reese had come through and I was supposed to come back, but this happening, like I said in the 200th episode, I wouldn’t have had it any other way.

Chicago Med, Wednesdays, 8/7c, NBC