What Happened to Sylvie Brett on Chicago Fire? A Wedding and a Goodbye

From Seasons 3 to Season 6 their relationship was primarily platonic as Casey was in a relationship with Brett's then-partner Gabby Dawson (Monica Raymund) and Brett was dating other people. After Casey and Dawson broke up, Casey and Brett grew closer due to their mutual heartbreaks. 

In Season 7 of Chicago Fire, Casey and Brett's relationship rew increasingly flirtatious — though that was when then-Fire Chaplain Kyle Sheffield (Teddy Sears) made his move and Sylvie briefly left Chicago to be with him. 

After she returned in Season 8 of Chicago Fire, the idea of a "Brettsey" romance became more of a possibility, particular after Casey became Brett's shoulder to cry on after the death of her mother.

RELATED: Look Back at Matthew Casey and Sylvie Brett's Relationship Over the Years

In Season 9, Episode 2 ("That Kind of Heat"), the tension between Brett and Casey reached a boiling point after they shared an intimate kiss after a stressful call. Despite Chi-Hards thinking this was the moment they'd been waiting for, Brett asked Casey to leave after realizing he still had feelings for Dawson.

She then briefly dated CFD Lieutenant Greg Grainger, before he realized her past with Casey prevented their relationship from flourishing.

In Season 9, Episode 15 ("A White-Knuckle Panic"), Casey revealed he was in love with Brett and no longer had any feelings for Dawson; she admitted she loved him, too, in Season 9, Episode 16 ("No Survivors"). By Season 10, the pair was happily dating, and everything was coming up roses. 

Sadly for Brettsey fans everywhere, the relationship experienced major turbulence after Casey left both Firehouse 51 and Chicago after becoming the legal guardian of his late friend's two sons who were living in Portland. The pair initially agreed to take a stab at a long-distance relationship, but the separation proved devastating to their momentum as a couple.

RELATED: Sylvie Brett's Departure During Chicago Fire Season 10, Explained

In the Season 11 premiere of Chicago Fire, Brett broke up with Casey over the phone. After the break-up, she explored a relationship with a minor league hockey player named Dylan before he broke up with her in the Season 11 finale.

It was then that Casey returned with a marriage proposal for Brett — but fans had to wait for Season 12 to learn she said yes. 

Brett made her way to Firehouse 51 in the Season 3 premiere of Chicago Fire ("Always").

She moved to Chicago from Indiana after being placed at 51 as the replacement for Leslie Shay (Lauren German) following Shay's death in the Season 2 finale. Due to the tragic circumstances of Brett's placement, she didn't receive the warmest of welcomes: She was paired up with fellow paramedic Dawson, who initially struggled to acclimate to her new partner.

RELATED: Kara Killmer Shares Behind-The-Scenes Pic from Chicago Fire Season 12

Brett was forthright about having no intentions of replacing Shay as a person; she just wanted to make a new home for herself. Sylvie soon became one of Dawson's best friends and forged several steel-tight bonds throughout the CFD, making her paramount to their success. 

Brett's move to the Windy City came after she'd left Indiana because she'd supposedly gotten cold feet before her wedding to her one-time fiancé. In Season 3, Episode 4 ("Apologies Are Dangerous"), it was shockingly revealed that she hadn't experienced cold feet — he had. Sylvie's ex surprised her and her colleagues with a visit to the firehouse to get her back, but Sylvie pointed him to the door after being reminded of his cold-hearted and controlling nature. 

Brett shared in the early seasons of Chicago Fire is that she was adopted and had never met her birth parents. But, in Season 8, Brett's biological mother Julie (Kelly Deadmon) reached out to her in order to reconnect. Having never met Julie before, Brett was hesitant to bridge the gap but ultimately met her biological mom in Season 8, Episode 15 ("Off The Grid"). 

Part of the reason Julie reached out to her was because she became pregnant with Brett's half-sister, Amelia. Hoping to forge a wholesome connection between her two daughters, Julie made an effort to win over the apprehensive Brett, who eventually warmed up to Julie.

Sadly, Julie was unable to welcome Amelia into the world the way she wished. After going into labor in Season 8, Episode 18 ("I'll Cover You"), Julie died during childbirth.

Amelia's father, Scott, was devastated by Julie's passing, forcing Brett to be potentially tasked with caring for her newborn half-sister. Fortunately, Scott was able to manage his grief and stepped up to his fatherhood role.

Brett's background as an adopted child and her subsequent connection with her biological mother laid the foundation for an exciting Season 11 plot line.

While responding to a 911 call in Season 11, Episode 20 ("Never, Ever Make a Mistake"), Brett and Violet Mikami (Hanako Greensmith) were tasked with delivering teen mother Amber's baby after she went into labor prematurely. The delivery was performed without a hitch but Brett was subsequently shocked to learn that Amber had no interest in raising the kid. The baby was put up for adoption using Firehouse 51's safe haven box that Brett had implemented, thus sparking a life-altering choice. 

Brett set forth to adopt the baby herself, which became complicated after Julia was placed in the foster system. In an effort to expedite the adoption process, Sylvie paid a visit to Amber to encourage her to reclaim custody for the sake of naming her the legal guardian and eventual adoptive parent of the child.

Amber agreed to the request, officially making Brett a mom. Brett named the newborn girl Julia after her late mother.

Brett's final episode of Chicago Fire was in Season 12, Episode 6 ("Port in the Storm"), during which she and Casey tied the knot in a "simple, intimate, and perfect" ceremony. After Brett and Casey celebrated their union with their loved ones, Firehouse 51 gathered to give them a touching send-off. 

"What I love about Sylvie is her resilience," Killmer told NBC Insider in honor of her final Chicago Fire episode. "These first responders that we're representing, they've experienced so much loss, so much trauma, and then they go back for more because they believe in what they're doing."

Killmer continued, "I feel like Sylvie's character really demonstrates that the most in that, yeah, she's this hopeless romantic, but she always continues to believe the best in people... She doesn't get weighed down too much by everything that she's seen and all of the loss that she's experienced. And that's a quality that I would like to take with me."