The ever-optimistic and empathetic Brett is leaving Chicago — but for a pretty awesome reason.

One of Chicago Fire’s brightest, long-running characters, Sylvie

Brett (Kara Killmer), is leaving the show. Yes, sadly, after 10

seasons, Brett is moving from the Windy Cindy to somewhere new — and with someone very special. To find out why Brett is leaving Chicago Fire, keep reading the story, below.

Why did Brett leave Chicago Fire?

In the Season 12 premiere (“Barely Gone”), Brett revealed to her Firehouse 51 loved ones that she planned to leave Chicago. After accepting Matthew Casey’s (Jesse Spencer) heartfelt proposal, Brett and Casey decided she would move with him to Portland to begin their married life together.

She revealed her plans to leave Chicago while discussing the wedding with Mouch (Christian Stolte) and Violet (Hanako Greensmith). After Mouch expressed confusion over the speed at which Brett planned to leave the Windy City, she clarified that after all these years of will-they-won’t-they chemistry, she and Casey deserve to be together once and for all. “Matt and I talked it through, and the truth is, we’ve waited long enough to be together full-time,” she said.

And Brett won’t be going alone. Fans will remember that Season 11 also ended with her becoming legal guardian to her baby, Julia.

Why did Kara Killmer leave Chicago Fire?

Killmer has spoken fondly of her time in Chicago and on the series. She shared a carousel of photos to Instagram in November 2023 from her early days in the city and reflected, “These are the very first few pictures I took, or was tagged in, when I first came to Chicago. Going up in the Squad 1 basket was my first exposure to the CFD—some of the best firefighters in the country! The view from my very first apartment was absolutely stunning and the beginning of a love affair with the gorgeous city of Chicago!”

Is Kara Killmer (Brett) leaving Chicago Fire for good?
At this point, there are no plans for Killmer to return to Chicago Fire, but when asked by NBC Insider if she’d be open to it, she said, “Oh, absolutely. The door is wide open. Any time they wanna call, I will be there. It is a fantastic show, great people. I will come back any time they want.”

All about Sylvie Brett, Firehouse 51’s sweetheart

A regular since Season 3, Brett is a paramedic who’s made appearances on both Chicago Med and Chicago P.D., making her firmly established in the One Chicago universe.

After some back-and-forth with her hometown fiancé, Brett dumps him for good and moves on with some of the men from the firehouse, most notably Casey, with whom she has a very strong connection. “Brettsey” was a slow-burn romance and a fan favorite, though when Casey left the show, it seemed to squash hopes of a potential happily ever after. Then, Casey came back for a cameo in Season 11 and ended up proposing to Brett! (She later accepted, of course.)

“We’ve always seen Sylvie in a relationship. We’ve always seen her in a romance. She’s a hopeless romantic,” said Killmer.

Though the One Chicago shows deal mainly in drama, off-camera, Killmer loves to goof around with her cast mates, and often posts snapshots of them being chummy on social media. She especially loves “The Ladies,” a.k.a. co-stars Miranda Rae Mayo and Hanako Greensmith, a.k.a. “Fire Trio.”