Erin Lindsay is a fictional character in NBC's Chicago TV franchise, as a lead character in Chicago P.D. and a recurring character in Chicago Fire and Chicago Med. Portrayed by Sophia Bush, she is a detective in the Intelligence Unit of the Chicago Police Department.
In season 1 of Chicago P.D., it has been established from the very beginning that Lindsay shared a special relationship with Hank Voight, head of the Intelligence Unit. Her unwavering loyalty to Voight is explained as her background is gradually revealed. She is generally unfazed by the gangsters, drug lords, and physically intimidating suspects the unit encounter on a regular basis. She has mentioned that her biological father was in prison and that he would hit her and her mother Bunny, who was an on-and-off drug addict. Through Bunny, she has a half-brother, Teddy Courtney, who was taken by a pedophilia ring at age 13 and was found by NYPD detectives ten years later working as a male prostitute. Lindsay grew up on the street and by the age of 14, she had already been arrested 5 times on charges including misdemeanor, simple battery, retail theft, solicitation, and unlawful possession of cannabis. She became a CI for Voight, who, along with his wife, eventually took her in as her legal guardians. Actress Sophia Bush described the character: "Lindsay comes from the street so she already knows how all these people work." She completed high school at St. Ignatius College Prep and joined the Chicago Police Department. After graduating from the police academy, she spent four years on the west side of Chicago as a patrol officer, which she said was all the education she needed.
Lindsay was born on April 11–12, 1985, and celebrated her 30th birthday during the events of the Intelligence/Special Victims Unit joint operation to apprehend a serial rapist, killer, and arsonist (portrayed by Dallas Roberts).
Because of her background, Lindsay is compassionate and sympathetic towards vulnerable young victims, especially girls, as she can relate with their situation. For example, she tries to get a 17-year-old prostitute and heroin addict, Nadia, to enter drug rehab twice. Eventually, she succeeds in convincing Nadia to stay clean and helps her get a desk job at 21st District headquarters.
The character was first introduced in Chicago Fire, as one of the Chicago PD detectives the firefighters of 51 regularly come into contact with. She began a relationship with Kelly Severide, the lieutenant of Squad 3. They eventually break up when he spirals out of control following Leslie Shay's death.
When Chicago P.D. premiered, it was established that she has been partnered with Jay Halstead for the past month. The first season coincided with the second season of Chicago Fire, during which she was still dating Lieutenant Kelly Severide from Squad 3.
In season 2, Lindsay was recruited for a DEA task force. In the episode "Disco Bob", Lindsay becomes disillusioned with the task force, with its seemingly-endless bureaucracy and the menial tasks her handler assigned to her (she was to spend a number of weeks with the target's wife, simultaneously pumping her for information and keeping her out of the task force's way), leading her to resign and return to the Chicago PD and Intelligence.
Lindsay's spiral downward begins with Nadia's death in the Law & Order: Special Victims Unit crossover episode "Daydream Believer". Nadia was an unfortunate victim of circumstances as she was murdered by sociopath Greg Yates, who had intended to target Lindsay. With this knowledge, Lindsay feels guilty and responsible. She begins drinking and becomes addicted to painkillers, egged on by her ne'er-do-well mother Bunny. In the season 2 finale "Born into Bad News", she turns in her badge and resigns; it is revealed in season 3 that Voight actually filed for a three-week sabbatical on her behalf instead of accepting a resignation. She returns in the season 3 premiere after learning that Halstead's undercover operation had been compromised and that he was being held hostage and tortured by a drug kingpin wanted by the Chicago PD. She gets clean, moves back in with Voight, and cuts Bunny out of her life as part of Voight's conditions for returning to Intelligence.
Since breaking up with Severide, Lindsay's main love interest in the show is her partner Jay Halstead. They share a close friendship, which has escalated to a more intimate relationship and cooled down at various times, due to Voight's vocal dislike for "in-house" romances. However, regardless of the status of their relationship, they remained loyal to each other as partners on the job and friends outside of it. Halstead is the only character other than Voight she has confided her past to in detail; likewise, she is the only character other than Mouse and Halstead's brother Will who knows about his traumatic past in the military. When Lindsay was on the federal task force, she starts seeing Halstead after work as they no longer had to worry about breaking fraternization rules. In the season 3 premiere, Halstead is the only one who persistently tries to help her, even after Voight had given up. Following her return from her "sabbatical", Voight tells Halstead that he no longer cares about the status of latter and Lindsay's relationship as long as Halstead is looking out for her. After some hesitation, she agrees to take the next step, and they go public with their relationship for the first time by kissing at Molly's. In the beginning of season four, they move in together.
In addition to her regular role on P.D., Lindsay has appeared in Special Victims Unit, Fire, and Med.Chicago Fire - "Rhymes With Shout" (November 26, 2013)
Chicago Fire - "Virgin Skin" (February 25, 2014)
Law & Order: Special Victims Unit - "Comic Perversions" (February 26, 2014)
Chicago Fire - "Keep Your Mouth Shut" (March 4, 2014)
Chicago Fire - "A Rocket Blasting Off" (March 11, 2014)
Chicago Fire - "A Dark Day (1)" (April 29, 2014)
Chicago Fire - "Real Never Waits" (May 13, 2014)
Chicago Fire - "Wow Me" (September 30, 2014)
Chicago Fire - "Nobody Touches Anything" (November 11, 2014)
Law & Order: Special Victims Unit - "Chicago Crossover" (November 12, 2014)
Law & Order: Special Victims Unit - "Daydream Believer" (April 29, 2015)
Chicago Med - "Mistaken" (December 8, 2015)
Chicago Med - "Malignant" (January 5, 2016)
Law & Order: Special Victims Unit: "Nationwide Manhunt" (February 10, 2016)