Summary
- According to co-showrunner, Brett's departure from Firehouse 51 in Chicago Fire season 12 won't be straightforward.
- Brett will take major risks and throw herself into her job like never before.
- With complications ahead, it's uncertain whether Brett will have a happy ending in season 12.
Chicago Fire co-showrunner Andrea Newman teases Brett's season 12 arc will have some major risks. Kara Killmer's time in One Chicago is coming to an end. After the season 12 premiere confirmed her engagement to Casey, moving with him to Portland, Oregon seemed like the perfect way to write the character out. However, it sounds like Brett's departure from Firehouse 51 will be anything but straightforward.
Speaking with Chicago Fire season 12, but Brett's personal work arc will also be exciting, albeit dangerous. As it turns out, she is motivated now more than ever to do a great job, resulting in her taking major risks. Read her full quote below:
“But in of the character… [Brett] kind of throws herself into the job in a way that we have never seen before. She has a lot of really, really big action this season. She is fully committed, and she takes some big risks—maybe too big.”
Will Brett Have A Happy Ending In Chicago Fire Season 12?
When news broke that Killmer was leaving One Chicago, Casey's cliffhanger proposal in the Chicago Fire season 11 finale naturally became the launching pad for her final arc. The season 12 premiere effectively laid it out with the pair engaged to be married in a few weeks, and the wedding will be in Chicago. After that, Brett will leave Firehouse 51 and the Windy City to be with her husband in his new home across the country. However, Newman makes it sound like there are some complications ahead of her.

Chicago Fire Season 12’s Casey Proposal Resolution Utterly Fails Brett
Chicago Fire season 12 finally solves Matt Casey's cliffhanger proposal in season 11, but it is at the expense of Sylvie Brett and her story.
Given the nature of their jobs, Brett and the rest of Chief Boden's squad have been through countless near-death experiences over the years. However, coupled with One Chicago's penchant for pulling unexpected demises, Newman's ominous tease about Brett's future in Chicago Fire season 12 can be a cause for concern. Considering her current role as a new mother to baby Julia, it's interesting that she will be more aggressive in taking big risks.
As seen before, happy endings are not impossible but rare in the NBC show. Almost everyone in Firehouse 51 has suffered a major loss since One Chicago started with the first-responder series. So, while things seem to go well for Brett, it isn't outside the realm of possibility that she will face some heartbreak just before she officially leaves in Chicago Fire season 12.
Source: Fangirlish