<P> The character has a well - documented feud with Detective Hank Voight (Jason Beghe), a protagonist on Chicago Fire spin - off Chicago P.D. . The introduction of Voight and other Chicago PD characters eventually led to the creation of the namesake spin - off, in which Voight's full story is further clarified in the first season . Although Voight is shown to be highly dedicated cop and earns the grudging respect of Casey's co-workers, his presence is still met with tension and suspicion from the firefighters of 51 as a result of what happened between him and Casey . Casey's storyline crosses with Voight once again in the season 3 finale of Chicago Fire, as he goes missing after agreeing to help Voight gather information on a client he was doing renovation works for . </P> <P> As the leader of the truck company, Casey's cool and standoffish demeanor and no - nonsense attitude sometimes puts his crew off but he is respected by them and highly regarded by Chief Boden . He is extremely private about his personal life, preferring to wallow in his own problems rather than seek help from his colleagues, and sometimes comes across as distant and aloof as he usually keeps to himself during down time even when around them in the lounge room . In the season 4 premiere, Herrman tellingly comments that the way Casey deals with things is "not dealing with it"; of all the characters, he generally confides to Severide or Dawson and only after he is at his breaking point . Despite this, Casey does care for his men and will not hesitate to defend them, even if it means standing up to his superiors and risking his own career . He trusts the men of his truck company implicitly (and vice versa) and is generally quite lax with them in good faith that they will maintain professional standards themselves, only disciplining them when he has no choice . However, he is known for being tough with candidates, as seen with Mills, Jones and now Borrelli and would either personally or have one of his more senior firefighters regularly drill them . </P> <P> Casey is also burdened by his ex-convict mother Nancy, who shattered the family 15 years earlier after murdering his abusive father . He has a sister, Christie, who he grew distant from over their father's death, but they have since mended their relationship . His family still remains a touchy subject and, according to veterans Mouch and Herrmann, there is an unspoken rule within the firehouse that no one is to mention Casey's family or ask him about them . HIs relationship with Gabriela Dawson is a major storyline throughout the series and they eventually marry in the series' 100th epsisode . </P> <P> A skilled handyman and carpenter, Casey freelances as a construction contractor when off - duty . Other characters have consulted him for advice on construction - related issues . For example, he was "consulted" by Herrmann on renovation works and building code compliance for Molly's and built a ramp for a paraplegic accident victim he and his men had rescued . </P>

Chicago fire why did casey's mom kill his dad
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