Kara Killmer as Paramedic Sylvie Brett, Ambulance 61 (Season 3—present): Sylvie is the new Paramedic for Ambulance No.61 replacing Leslie Shay following her death. Brett is a small-Midwestern-town girl from Indiana and is a "runaway bride" who goes "up I-65 to Chicago" to escape her ex-fiancée Harrison after their engagement fell apart. Initially she has difficulty adjusting to city life due to her naiveté, as shown by the fact that she leaves cash out on the table with the windows open and rented an apartment in a neighborhood known for crime because the rent was cheap. She is currently in a relationship with Joe Cruz and shares an apartment with Gabby Dawson.
Monica Raymund as Paramedic in Charge/Firefighter Candidate Gabriela "Gabby" Dawson, Ambulance 61: Dawson has recently found herself in trouble for leaping before she looks on various calls, which leads to her being written up several times. She also pursues a flirtation with the emotionally unavailable Casey, with whom she shares a very strong friendship. Later, she and Mills bond over their mutual love for cooking and begin a relationship in secret. When their relationship is brought to light, Casey seems to be jealous and pulls rank to keep them apart at work. She later discovers that Boden had had an affair with Mills's mother, and she keeps this knowledge from him. When he finds out that she had known about it and that she still has feelings for Casey, he ends their relationship but they remain mutual friends. In Season 2, Dawson and Casey start a very serious romantic relationship and Casey proposes to her. She later is a Candidate in the Fire Academy. She fails her physical exam by several seconds, after injuring her ankle. In season 3, she has passed the Fire Academy. However, her relationship with Casey poses a problem due to fraternization rules and she is initially assigned to Firehouse 105 in Austin under Casey's nemesis Lieutenant Welch. Welch was against her assignment to his truck company due to a past bad experience with a female firefighter. He fills the spot and she is assigned as the Candidate on Truck 81, under Herrmann's supervision. During her first few weeks on the job, Casey is extra protective of her, much to Herrmann's frustration, but she eventually settles in. Like the actress, Dawson is of Dominican descent. Her older brother Antonio is a Chicago PD detective (he also features in the spin-off Chicago P.D.).
Monica Raymund as Paramedic in Charge/Firefighter Candidate Gabriela "Gabby" Dawson, Ambulance 61: Dawson has recently found herself in trouble for leaping before she looks on various calls, which leads to her being written up several times. She also pursues a flirtation with the emotionally unavailable Casey, with whom she shares a very strong friendship. Later, she and Mills bond over their mutual love for cooking and begin a relationship in secret. When their relationship is brought to light, Casey seems to be jealous and pulls rank to keep them apart at work. She later discovers that Boden had had an affair with Mills's mother, and she keeps this knowledge from him. When he finds out that she had known about it and that she still has feelings for Casey, he ends their relationship but they remain mutual friends. In Season 2, Dawson and Casey start a very serious romantic relationship and Casey proposes to her. She later is a Candidate in the Fire Academy. She fails her physical exam by several seconds, after injuring her ankle. In season 3, she has passed the Fire Academy. However, her relationship with Casey poses a problem due to fraternization rules and she is initially assigned to Firehouse 105 in Austin under Casey's nemesis Lieutenant Welch. Welch was against her assignment to his truck company due to a past bad experience with a female firefighter. He fills the spot and she is assigned as the Candidate on Truck 81, under Herrmann's supervision. During her first few weeks on the job, Casey is extra protective of her, much to Herrmann's frustration, but she eventually settles in. Like the actress, Dawson is of Dominican descent. Her older brother Antonio is a Chicago PD detective (he also features in the spin-off Chicago P.D.).