Played by Kevin Chapman, Lionel Fusco was a dirty cop when he was introduced in Person of Interest season 1, but what sent him down this road in the first place? Fusco, who worked as a detective for the NYPD, was a main character through all five seasons of Person of Interest. At the beginning, Fusco was an unwilling ally of the team, as they regularly relied on Fusco's connections to help people who were in danger.
Detective Fusco first appeared in the pilot episode of Person of Interest as a member of a group of corrupt police officers that Reese (Jim Caviezel) encountered on his first mission for Finch (Michael Emerson). After Reese was captured, Fusco was entrusted with the task of taking Reese off to a secluded area and executing him, but Reese overpowered him. Afterward, Reese killed Fusco's friends and threatened to frame Fusco for it if he didn't help him. This was the beginning of a strained and complicated relationship, as Reese often had to turn to Fusco for information that only he had. To save his own skin, Fusco had no choice but to comply.
Fusco was by no means a good guy when viewers first met him on Person of Interest, but later episodes revealed more sides to the character, and led to questions about how and why Fusco became a dirty cop. A season 2 episode explained that it all started when he became friends with Detective Stills (James Hanlon) in 2004. Stills called in a favor from Fusco to help cover up a shooting by a fellow police officer. Fusco agreed to help out of loyalty to Stills, and this was just the beginning of Fusco's fall, as it wasn't the last time that Stills relied on Fusco's position as a homicide detective. Later, Fusco was asked to help cover up the killings of a few criminals so the cops could steal their drug money, but Fusco refused until one rushed into the room, causing Fusco to shoot him on impulse. After that, he was a part Stills' group. From then on, Fusco was a willing participant in their illegal operations, taking his cut of stolen money and killing criminals.
Fusco told Detective Carter (Taraji. P. Henson) that he justified his actions by thinking that in helping Stills, he was helping to clean up the streets, and that there was no harm in taking money from a dead drug dealer. By aligning himself with people like Stills and recurring villain Simmons (Robert John Burke), Fusco went down a dark road, and it took quite a while for him to come back from it.
Person of Interest was a story of redemption for several of the show's characters, and Fusco was no exception. With every bad thing that Fusco had done, Person of Interest originally presented him as a character who may not be worthy of redemption, as even Reese clearly didn't care what happened to him at first. But over time, Person of Interest transformed Fusco into a good person again by having him work with Reese, Finch, and Carter. Though Fusco was the team member who was in the dark about the Machine for the longest time, he assisted Reese and Finch with tracking down the Machine's numbers, and found himself feeling good about helping people. Person of Interest showed that even a person like Fusco could change, and through him, the show created a compelling redemptive arc.