He was dating Linda, who slept with Jimmy at Jimmy's engagement party, and became pregnant. When Joe found out, he slugged Jimmy in the face. Later, Jimmy was missing in a burning building, and Joe forgot their differences to go back inside and find him. Jimmy escaped and wanted to go back for Joe, but it was not safe. Luckily, Joe was rescued and taken to hospital, where he married Linda from his hospital bed. Played by Nick Sandow. Firefighter Stu "Lotta Zs" Szczelaszczyk Stu joined the show in 2004. His nickname arose from the number of "z"s in his surname. Carlos previously knew of Stu due to him being the center for the interdepartmental basketball team. After the series finished, he was promoted to Lieutenant and took over Jimmy Doherty's rescue squad. Played by Jason Shaw. Firefighter Billy Walsh Originally called Jeff Wilson, the character soon became known as Billy Walsh, the same name of the actor playing him. Little is known about him - he is married and in 2000 he mentioned his wife was expecting a baby. He was promoted to Lieutenant after Jimmy Doherty left in 2004, and . Played by Bill Walsh. Police Sergeant Jason Christopher Sgt Christopher was the sergeant in Seasons 2 and 3. He did not particularly like Bosco. He was engaged to be married at one point, but transferred out of the 55 before being replaced by Maritza Cruz. Played by Brad Beyer. Officer Brooke Doherty Brooke did not work at the 55, but was assigned to the 89 precinct. She met and fell in love with Jimmy Doherty at a supermarket, thanks to Jimmy's son Joey, and the pair got married. Brooke left Jimmy after finding out he'd slept with his friend Joe Lombardo's girlfriend at his engagement party, and filed for divorce. Played by Eva LaRue. Captain "Stick" Elchisak Captain Elchisak, often referred to as "Stick" by senior officers, was the commanding officer for the 55th precinct at least from 1999-2002. Stick often had run-ins with Bosco, particularly when Bosco had sex with his daughter in the front of an on tape (the Captain did not know it was his daughter). The Captain stopped appearing after Season 3 and it is unknown whether or not he continued commanding the 55, as Lt. Swersky seemed to have all but assumed command of the precinct. His first name is never revealed.