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What Happened to Kelly Severide's Half-Sister Katie Nolan on Chicago Fire?

In a short period of time, she found a sibling, fell in love, became the victim of a terrible crime, and left.

By Megan Lasher
Severide and 51 Rescue a Man Trapped in a Burning Recording Studio | Chicago Fire | NBC

Katie Nolan (Brittany Curran) was a complicated figure on Chicago Fire. Originally introduced as Benny Severide's (Treat Williams) daughter and Kelly Severide (Taylor Kinney)’s half-sister, she wound up in a long-term relationship with Firehouse 51’s firefighter, Brian “Otis” Zvonecek (Yuri Sardarov), who ultimately died in the line of duty in Season 8 — devastating all who loved him.

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Watch Chicago Fire Wednesdays at 9/8c on NBC and next day on Peacock.

Revisit Katie’s timeline on Chicago Fire and what ultimately happened in all of her complex relationships with the firehouse.

Who is Kelly Severide’s sister Katie Nolan?

In Season 2, Episode 5 (“A Power Move”), Severide — who'd begun to reconcile with his philandering, firefighter father in Season 1 — saw Benny, embracing a much younger woman. He immediately assumed that this mystery woman was someone his father was dating, but it was eventually revealed that she was Katie, Severide’s half-sibling.

RELATED: What Happened to Kelly Severide on Chicago Fire? 

The fact that Severide was her brother remained a secret to Katie until Season 2, Episode 7 (“No Regrets”), after which the two attempted to spark up a relationship, despite having gone their entire lives without knowing the other existed.

In the following episode (“Rhymes with Shout”), Katie decided to come cook at the firehouse as practice for her catering career, but ended up not showing up. When Kelly found her to ask why, she revealed that she was terrified Kelly would be exactly like Benny and leave her after finally making his way into her life.

Katie Nolan’s Relationship with Benny Severide

Benny was notoriously not a fantastic father, and he told Severide in Season 2, Episode 5 that he had not been much more present in Katie's life than he had been in his son's.

Katie even expressed a fear that she was similar to her father when meeting with Kelly one-on-one in Season 2, Episode 13 ("Tonight's the Night"). She had just received a job opportunity in New York and, when she considered leaving, she asked her brother, "Am I being Benny?" — in part because she'd developed a relationship with Severide's colleague Otis. 

RELATED: Who Is Benny Severide? What To Know About Kelly Severide's Dad on Chicago Fire

She ultimately took the job anyway.

Katie returned to Chicago for Benny's funeral in Season 7 and reunited with Severide to mourn their shared father. She watched tearfully as her brother gave their father's elegy, allowing her to see the positive side of the father she'd spent a long time not liking. 

Katie Nolan and Brian “Otis” Zvonecek's Relationship

Chicago Fire Otis Recap Katie

As she got to know the rest of the Chicago Fire crew in Season 2, Katie hit it off with Otis. The two bonded over their love for the board game Settlers of Catan in Season 2, Episode 11 ("Shoved in My Face") and Otis subsequently invited Katie over for dinner.

RELATED: What Happened to Otis Zvonecek on Chicago Fire? 

Otis told Severide about his crush, asking for permission to pursue a relationship with Katie. However, Katie got job offer in New York and then became the victim of a kidnapping. After her rescue, she announced in Season 2, Episode 14 ("Virgin Skin”) that she needed to leave Chicago to stay in Colorado while she processed and recovered from the trauma of the event.

In Season 7, Episode 7 ("What Will Define You"), Katie and Otis shared one more moment together after she returned to Chicago for her father's funeral. Katie shared with him that she was working at a restaurant in Boulder with her boyfriend, and asked him about his new girlfriend, Lily, making for a sweet final conversation. 

What happened when Katie Nolan was kidnapped?

In Season 2, Episode 13, Katie was planning to tell Otis about her job offer in New York, but did not end up getting the chance amid a city blackout. She did tell Otis she had something to tell him, but goings-on at the firehouse were interrupted when a local criminal, Vince Keeler (Jake Weary), had a physical altercation with another man, which was broken up by Severide. "You're a dead man," Keeler said as Severide kicked him out of 51. 

RELATED: The Biggest Villains from All 11 Chicago Fire Seasons

Chicago P.D. officers let the team know that Keeler was "huffing and puffing that he's going to kill a fireman tonight," prompting the team to be on lookout. As Katie walked home at the end of the episode, she was kidnapped by Keeler and one of his friends as retribution for Severide's actions. 

In the next episode, "Virgin Skin," Severide worked with the P.D. to find where Keeler had hidden his sister. He finally got an answer for her location after violently forcing it out of one of the perpetrators, and he was first on the scene to save her. She was beaten up pretty badly and ultimately revealed that Keeler had sexually assaulted her.

Though Keeler was arrested for the assault before Katie left town in Season 2, Episode 14, he was released without charges and returned to Firehouse 51 in Episode 15 ("Keep Your Mouth Shut") to mock Severide. At the end of the episode, however, police discovered Keeler had been abducted from his gym, and his car and cellphone were found abandoned — after Severide and others had made and discarded plans to exact revenge, while rejecting help with said plans from Benny.

In Episode 16 ("A Rocket Blasting Off"), some at Firehouse 51 were under investigation for Keeler's disappearance, and Severide came to realize that Benny was responsible. Benny privately confessed to Chicago P.D.'s Sgt. Hank Voight (Jason Beghe), who suggested the former firefighter lie low in Wisconsin for a while. 

Katie ultimately recovered from her ordeal while building a new life for herself in Colorado.