Chicago Fire Season 12 Finale Has A Secret Sylvie Brett Bombshell You May Have Missed

Change is all around as Season 12 of "Chicago Fire" comes to an end — even for characters who are no longer around themselves. In an Easter egg many fans might have missed at first glance, it looks like the recently-departed Sylvie Brett (Kara Killmer) has embraced her marital status in more ways than one. 

Take a closer look when Stella Kidd (Miranda Rae Mayo) is talking to Kelly Severide (Taylor Kinney) about getting a picture of Sylvie's adopted daughter — while they also discuss a big change that might result in their family expanding during Season 13. The contact initials visible on the phone no longer spell out SB, but SC – as in Sylvie Casey. Yep, that means Sylvie has taken on her husband Matt's (Jesse Spencer) last name. Quite the show of tradition for a couple that could be as nontraditional as they come, but definitely a display of familial solidarity towards the blended family of kids they're now raising together. 

Speaking of raising a family, Kara Killmer has said she'd gladly return for a "Chicago Fire" guest spot –and is hoping that one very pro-Brettsey condition will apply.

Kara Killmer has confirmed that she'll return to "Chicago Fire" for a guest appearance any time the show's willing to host her — and would love it if Sylvie could do so as a pregnant person. "Casey, ever since Season 1, all he wanted was to be a father," Killmer told TV Line in 2024. "So whether they're adopting children and kind of creating a patchwork of a family for themselves or — yeah, I hope they get on it and have a couple of babies themselves. That would be great. That's how I picture their future for the next couple of years, for sure." 

It's not as if Matt and Sylvie won't already have parenting experience; Matt is acting as a ward for Griffin and Ben Darden, the teenage progeny of the long-dead Andy Darden (Corey Sorenson). Matt's also the adoptive father of Sylvie's recently-adopted daughter, Julia. The whole family resides together in the Pacific Northwest, which is one of the many reasons both Sylvie and Matt have left Chicago behind — at least for the moment.