Jay is the younger brother [1] [2] of Dr. Will Halstead , a former main character on Chicago Med. He was portrayed by Jesse Lee Soffer. The Halsteads are from Chicago. Little is known about their family as neither brother talks much about it.
Jay's brother Will, a doctor on Chicago Med, mentions that they are third-generation residents of the historically Irish-populated South Side neighborhood of Canaryville. They are from a blue-collar Irish Catholic background and both brothers attended Catholic school.
Both were bullied as kids but always held their own, earning respect from their peers. Their mother passed away from cancer; it was noted she was dying while Jay was deployed, but he came back to care for her. Neither brother has had a good relationship with their father Pat, as he disapproved of their career choices. Therefore he hadn't spoken to Pat in almost 2 years but still loved him.
While Will was able to reconcile with him, Jay never did and only discovered after Pat's death that the latter was actually proud of him as well. He later admits to Upton that he found therapy helpful, though it is not until the season 6 episode Trigger that Halstead speaks at length about how his time overseas affected him, telling Upton that he had learned to deal with his PTSD and not let the past trauma define him.
Jay Halstead had been in the Intelligence Unit for a month when the show premieres. As a skilled marksman and a former Ranger, he provides the tactical know-how and is often the designated sniper covering for the team when needed. His interrogation tactics are blunt and tough.
