Kara Killmer is leaving Chicago Fire and the season 12 premiere might have just revealed when

Two weeks before production on Chicago Fire season 12 began, word broke that longtime cast member Kara Killmer would be departing the show after ten seasons on the show.

While it was confirmed that Killmer would be leaving the show sometime in season 12, no update was provided initially regarding when Brett might leave town or how she would be written off. However, the season 12 premiere quickly provided fans with an answer on the specifics of how Brett will be leaving the show and when we might have to bid farewell.

Warning spoilers ahead from the Chicago Fire season 12 premiere!

Brett said yes to Casey's proposal... and that's how they're writing her off the show

Within minutes of the new season of Chicago Fire, the writers revealed that Brett had accepted Casey's proposal with the big reveal coming in the most unexpected of ways. Due to the show jumping ahead six months, we didn't get to see Brett accept Casey's proposal but instead learned she said yes when her ring got caught in her 51 locker.

Fast forward a few minutes after 51 responded to their first call of the new season and NBC finally offered up new information about the proposal. We found out that Brett not only accepted the proposal, but she's planning on moving to Portland with her newly adopted daughter, Julia, to live with Casey and the Darden boys.

When news broke that Kara Killmer was leaving the show, many speculated that the show might use Casey's proposal as a way to give the two characters a happy ending timed to Killmer's exit from the show. Fortunately, this indeed appears to be the plan which is a major win for Brettsey fans. I mean sure, we don't want to lose Brett but knowing the character will be getting a happy ending definitely helps to soften the blow.

Brett is likely to leave Chicago Fire early in the season

During the season 12 premiere, we learn from Brett that she's going to be leaving Chicago to move to Portland to live with Casey after their wedding. In the conversation, Brett reveals that the wedding will take place in Chicago and is coming in a month and a half.

This seems to suggest that Brett is going to leave the show sometime in the early part of the season, the key being the timing for how the early episodes of the season will play out. If the show's timeline lines up with the schedule for when NBC will be airing episodes, that would mean Brett's final episode should air sometime in mid-to-late February.

If that is the case, it seems like Kara Killmer will only appear in a small handful of this season's episodes with her exit likely coming around the mid-season mark. Given the season will be a shorter season due to the 2023 writers' and actors' strikes, this means we might only see Killmer in 5-6 episodes this season and we're going to enjoy every moment we get this season with Brett!