Kelly Severide

Severide graduated at the top of class at the academy and held the record for the youngest firefighter to make squad when he was 23 years old.[1] He and his long-time colleague and close friend Matthew Casey of Truck 81 have known each other since their days at the fire academy but have a falling-out over the death of their friend and colleague Andy Darden, whom Severide has known since childhood, over a botched-up call, which is where the pilot picks up. They work things out by the end of the season.

The son of CFD Captain Benny Severide (Treat Williams), Kelly was raised by his mother, Jennifer Sheridan (Kim Delaney), after Benny left the family when Kelly was in elementary school. Although Kelly has since reconnected with his father, they still share a love-hate relationship. He is often known to the "white shirts" (high-ranking officers) as Benny's son[2][1] but never used his father's name to advance his career, instead carving out his own reputation as a highly competent firefighter with excellent arson investigative instincts. By Season 8, Kelly is being openly recruited by the CFD's Office of Fire Investigation, though he consistently maintains his desire to remain with Squad.

His charismatic personality makes him a popular figure with both his colleagues and the ladies. He tends to be casual with his men and can be seen at the squad table or in the lounge chatting or playing cards with the rest of the firehouse. Despite this, he tends to keep his private problems to himself and lets it simmer, which often worries his chief. In contrast to Casey, he is highly adept at reading people, especially his own colleagues, and his observation skills have come to the fore in several arson investigations; in season 2, he correctly predicted that Hadley had been targeting the men of 51 and that Candidate Rebecca Jones, who committed suicide just months after graduating from the academy, lacked the discretion and inhibitions to truly excel as a firefighter (although she was later revealed to suffer from clinical depression).

At the beginning of season 1, Severide is at loggerheads with Matthew Casey over the death of a colleague and is plagued with a neck injury (fracture, C5 vertebra) that puts his career in jeopardy. He hides this from everyone except Shay, from whom he gets painkillers to deal with his injury. When he finally sees a doctor "off book", he is told that his condition is severe. His options are surgery, followed by rehabilitation for six months to a year, during which time he'd be off work. If he does nothing he risks weakness in his hands, muscle atrophy, and other symptoms that would eventually prevent him from working.

The doctor does not mention an experimental procedure. His girlfriend at the time, Renee Royce, tells him of an experimental procedure, which he undergoes to save his spine. After the injury, a paramedic candidate threatens his career with a false allegation of sexual harassment, however charges were dropped after Antonio Dawson runs a background check on her and discovers that she is a fraudster.[3] In Season 2, Kelly discovers he has a half-sister, Katie Nolan, who is a culinary student. He tries to reach out to her but she is initially hesitant as she and her mother had been abandoned by his father Benny. The two become close and Kelly is shown to be very protective of her. In the episode "Tonight's The Night" of season 2, Katie is kidnapped and Severide tries to find her in the following episodes. After she is found, she leaves for Colorado. When Katie's kidnapper disappears, Severide becomes a suspect. However, Benny Severide is revealed to be responsible but is let off by Detective Voight after Benny explains himself.

In Season 3, Severide has plunged into grief with Shay's death during a call (later discovered to be murder and arson).[4] He and Gabby Dawson aid Detective Voight's team in the preliminary investigations, which leads them to a series of unsolved arson cases, including the fire that killed Mills' father and seriously injured Chief Boden. The case crosses-over into the Chicago P.D. episode "A Little Devil Complex" and the perpetrator is killed by Antonio Dawson. Severide moves in with Casey and Dawson and avoids the apartment he and Shay shared as he is unable to face the loss of his best friend.

Severide is demoted in season 4 as part of Chief Riddle's plan to make Fire Commissioner by replacing Severide with Captain Dallas Patterson and then ousting Boden as Battalion Chief.[5] The men of Squad 3 remain loyal to him despite Patterson's efforts to win them over. Severide has a tough time during his demotion, constantly being undermined by Patterson. Patterson ordering him does not sit well with him and he has a hard time accepting that he's no longer Lieutenant. He gets suspended for a shift for threatening to hit Patterson. Severide and Gabby think Dallas is trying to replace everyone and get them all fired. Patterson doesn't understand this accusation and has a hard time understanding what he's doing wrong, but the fact that he is slightly unfriendly makes them all wary of him. Benny gives Severide a file on him to ultimately blackmail Patterson, Severide decides to hand the file to him. Patterson still doesn't understand why he would give it to him but he helps to calm Riddle down after Boden charges at him with accusations, which Severide is surprised to see. He[6] and Boden are later reinstated as Patterson is revealed to have used his connections to Riddle to implicate the latter for corruption.

In a Chicago P.D. crossover episode "Don't Bury this Case", Severide is accused of a hit-and-run accident, which later turns into vehicular homicide when one of the victims, a child, dies from her injuries. Lindsay and Voight suspect that Severide was set up, while friendships and relationships are put to the test as the detectives and cops are forced to toe a very thin line with their friends at Firehouse 51 as the evidence against Severide mounts. When drug and alcohol abuse from his past comes to light, detectives within Intelligence are skeptical in believing his innocence. He is eventually found to be innocent.

Severide temporarily blames Cruz for Herrmann getting stabbed by Freddy for bringing him to the firehouse in the first place and pressures him in to finding Freddy when he runs away. Chief Boden tells him to back off. He goes to look for Cruz and tries to find Freddy at their 'gang hideout', telling him to not risk his life unless he wants to be the one in the hospital.

Kelly develops a brief attachment to Bianca Holloway at CPD when he tries to tell her that a missing body they find is a young girl who disappeared from his neighbourhood a few years ago. She is initially irritated at his efforts in trying to identify the girl and tells him to back off. However, Severide is right and later on, she asks him for a favour - to look after her son JJ - while she prepares for a court hearing on a dangerous gang she has been detecting for some years. On the day of the hearing, she drops JJ off with Kelly for a few hours.

However, CPD is soon at the firehouse and informs Severide that Detective Holloway was shot outside the court. He is upset to hear this but insists that JJ stay with him until his aunt, who has requested not to tell JJ about this, has flown in from California. The firehouse help JJ with a school project, trying to divert his attention from his mother. A few hours later, Detective Crowley from CPD is back to tell Severide that Holloway died during surgery. He still insists that JJ stays with him until her sister arrives. She arrives later that night and asks Kelly to help her break the news to JJ. They tell him with the whole firehouse watching from the window. He breaks down and Mary takes him away. Just before he leaves, Severide gives Pouch, their dog who has also grown close to JJ.

Severide later has trouble with his relationships and starts thinking about his life. He is injured in an accident and doesn't get it checked out until Chief forces him to. He meets Chicago Med's Dr Clarke - a past friend of his, who asks him to take a quick blood sample and enroll on the bone marrow registry. After seeing the woman he is a match for, Severide agrees. Clarke tells him he'll feel the pain for months, to which he replies, "good". After donating his bone marrow, they develop a relationship for a few months, however her cancers returns and she eventually dies in his presence.

In season 8, Severide is offered a temporary position as an investigator for the Office of Fire Investigation (OFI). He initially turns it down, but is later assigned to the Office of Fire Investigations at the request of Fire Commissioner Grissom (Gary Cole). Severide goes to Grissom to confront him about the assignment, but Grissom convinces him to accept the assignment, and Severide asks for Grissom to shut down the investigation into Christopher Herrmann after he confronts a Chicago Police officer during a call. In the episode "Stand Our Ground", he returns to Firehouse 51 after completing his stint working as a Fire Investigator.