It was anything but business as usual at Firehouse 51 in Chicago Fire Season 12. With delayed production, beloved characters leaving, surprise engagements, and the lingering absence of one of the show’s foundational figures, NBC’s flagship firefighting series leaned into change — and the result was a season that felt more personal, more unpredictable, and more emotionally resonant than ever before.
Let’s break down what made Season 12 a rollercoaster ride for fans — and what it means for the future of the One Chicago franchise.
A Delayed But Anticipated Return
Following its early renewal in May 2023, Chicago Fire was expected to charge into its twelfth season with full steam — but the 2023 SAG-AFTRA and WGA strikes put production on hold. When the show finally returned on January 17, 2024, viewers were more than ready to dive back into the chaos, camaraderie, and close calls at Firehouse 51.
Sandwiched between Chicago Med and Chicago P.D. on NBC’s Wednesday night lineup, Season 12 opened with a sense of urgency — both in its plotlines and in its need to address dangling threads from the Season 11 finale.
A Season of Shifting Dynamics
From the outset, Season 12 felt different. The tone was more introspective, leaning into the personal stories behind the uniforms. And with the cast in transition, every episode carried a sense of uncertainty.
The Big Cliffhangers Carried Over
Season 11 ended with Mouch (Christian Stolte) fighting for his life after being shot on the job. The finale left fans in shock — and uncertain if he would survive. Season 12 wasted no time picking up that thread, showing a fragile but recovering Mouch, once again leaning on his Firehouse 51 family.
Meanwhile, Brett (Kara Killmer) was left stunned by a surprise proposal from Captain Matt Casey (Jesse Spencer), who had returned to Chicago just long enough to make waves. Their relationship, once torn apart by distance, was suddenly at the forefront again — complicated further by Brett’s recent adoption of a baby during Season 11.
Familiar Faces Leave, New Ones Step In
Season 12 became a turning point for several characters — some departing for good, others returning with new purpose.
Taylor Kinney’s Return (and Uncertainty)
After taking a leave of absence in early 2023 for personal reasons, Taylor Kinney’s absence as Kelly Severide was explained away in-universe by enrolling his character in an elite arson investigation program. But when he failed to return to Chicago, Stella Kidd (Miranda Rae Mayo) packed her bags and went to find him — setting up one of the season’s central off-screen arcs.
Kinney’s return was confirmed ahead of the premiere, but how many episodes he’d appear in was unknown — leaving fans watching each week with bated breath. When Severide did return, it was emotional, complicated, and far from the fairytale reunion viewers may have hoped for.
The Final Farewell to Sylvie Brett
Perhaps the biggest goodbye came from Kara Killmer, who exited the series in Season 12 after nearly a decade as paramedic Sylvie Brett. Her storyline — including her rekindled romance with Casey and new role as a mother — suggested a move westward and a hopeful new beginning.
Though her departure was confirmed in late 2023, the emotional resonance of her final episodes gave the character a proper sendoff. Longtime fans were bittersweet but grateful to see Brett’s story conclude on her terms — with love, family, and a clear future.
Blake Gallo Bows Out Early
Alberto Rosende also said goodbye to Chicago Fire in Season 12. His character, Blake Gallo, had grown from rookie hotshot to dependable team member, but his sudden decision to leave the firehouse surprised even his colleagues. His final appearance came in the season premiere, signaling that Season 12 would continue the trend of reshuffling its roster.
New Blood at the Firehouse
To fill the gaps left by exiting characters, Chicago Fire introduced a few new faces, including Rome Flynn (How to Get Away with Murder), who debuted in Episode 2. His character added fresh energy and a bit of mystery to the firehouse dynamics — though fans are still learning where he fits in the complex 51 hierarchy.
Returning cast members Miranda Rae Mayo, David Eigenberg, Joe Minoso, Hanako Greensmith, and Eamonn Walker helped anchor the season amid all the change. And of course, Christian Stolte’s recovery arc gave Mouch one of his most heartfelt storylines in years.
Where Season 12 Leaves Us
By the end of the season, Firehouse 51 looked different, but the core spirit remained.
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Mouch was back in action — scarred but still standing.
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Herrmann (David Eigenberg) was being eyed for a leadership role, perhaps foreshadowing a new rank in Season 13.
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Casey and Brett had seemingly found their happy ending — off-screen, but intact.
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Severide and Kidd were finally reunited, though questions linger about what they want next.
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And new dynamics between paramedics, squad members, and lieutenants started to reshape the team’s chemistry.
Looking Ahead to Season 13
If Season 12 was about transition, Season 13 promises to be about transformation. With key vacancies filled and storylines reopened, Chicago Fire is poised to keep evolving. Taylor Kinney’s ongoing presence remains a wildcard. And with Brett and Gallo gone, new relationships and rivalries are bound to emerge.
One thing’s for certain: Firehouse 51 isn’t done surprising us. Through heartbreak, heroism, and high-stakes rescues, the series continues to find new ways to make us care — and come back for more.
