Casey is back!

Jesse Spencer will officially return for Chicago Fire‘s season 10 finale, which is set to air May 25, ET has learned.

The episode, which centers on Severide and Kidd’s long-awaited wedding, begins filming Friday.

Spencer’s return to the NBC firefighter drama marks the first time viewers will see him back onscreen after he exited the series during the 200th episode earlier in the season. At the time of his departure, which was a surprise to many, the actor kept the door open for an eventual return.

Co-showrunners Derek Haas and Andrea Newman spoke with ET on Wednesday and held out hope that Spencer would be available to come back for Severide and Kidd’s big day.

“We basically got down on one knee and begged and pleaded for him to come back because, at the end of the day, Casey promised to be Severide’s best man and he’s a man of his word,” Newman said. “Jesse is a fantastic human being who is still very connected to that Casey character, so thankfully the schedule worked out and he could do it. We couldn’t have been more thrilled.”

Writing Spencer’s return “was incredibly emotional,” Newman shared, adding that she’s anticipating some teary-eyed cast and crew when he steps back on set on Friday. “We were just talking about it yesterday in our tone meeting, the scene where we first see him, I get choked up every time I read the scene. So just knowing and imagining him being there — everyone in the cast feels this as well — we know it’s going to be emotional for everybody.”

As writers, it was important to acknowledge all that has transpired since Casey left for Portland, Oregon, and how his absence has changed the firehouse.

“We wanted to give the character his due in the sense of how much he’s missed and what an important part of the show he was and always will be,” Newman said of what they wished to accomplish in his first scene. “There’s a line that Severide says to Casey, ‘It hasn’t been the same without you and it never will be.’ And the parenthetical we put in that was, ‘Speaking for all of us.’ Like, Severide says that he’s not just speaking for Severide’s character but for all the characters and for all of us who have ever worked with Jesse, who is amazing as a human and as an actor. We wanted to convey how important that character is to Chicago Fire and always will be.”

Haas teed up the anticipated final episode of the season, calling Severide and Kidd’s wedding “a long time coming.”

“We’ve watched their relationship grow and have obstacles that they’ve overcome for the last five seasons. And really, what Andrea and I are super proud of is the growth that Severide has shown over this since the inception of the show,” he previewed. “Now he’s the guy who says, ‘I got ya, Stella Kidd.’ That feeling of two souls who are both a little bit damaged but made for each other coming together in a ‘Chicago’ wedding that’s going to be the most memorable one that we’ve ever done is to us the perfect icing for a season 10.”

But, in classic “Chicago Fire” style, don’t expect the road to their nuptials to go smoothly. “I like finales that give the finales exactly what they want, everyone’s happy and if it ends with a campfire and everyone singing, ‘Kumbaya,’ and roasting marshmallows, that to me is an ideal finale,” Haas joked, clearly alluding to the couple facing unforeseen obstacles in the finale.

As for what they were willing to tease about the Casey and Brett of it all, Newman reminded viewers that they’ve been having a go at the long-distance thing all season, with Brett recently spending time with her boyfriend in Oregon. When they return to the Windy City for their friends’ wedding, it’ll force them to take stock on where their own relationship stands.

“At any wedding, you kind of tend to re-evaluate your own relationship. You’re looking at this wedding and you’re looking at what you have or what you can’t have. And I think it brings up all sorts of questions for their relationship and that dynamic — that long-distance dynamic that can be so difficult,” Newman hinted. “It will really shine a light on that. It’ll be a lot of questions about that.”

But could they also walk down the aisle too in the finale for a possible double wedding? “Leave that question mark,” Haas played coy, with Newman chiming in: “Leave that question mark. Double question mark.”

Chicago Fire” airs Wednesdays at 9 p.m. ET/PT on NBC.


More from ET:

‘Chicago Fire’ Boss on Kidd and Severide’s Tense Fall Finale Reunion

‘Chicago Fire’ Boss on ‘Suspenseful’ Fall Finale and Kidd’s Return

Jesse Spencer Shares Emotional Video After ‘Chicago Fire’ Exit

‘Chicago Fire’ Shocker! Star Explains ‘Difficult Decision’ to Leave