At some point, Jim joined the U.S. Marine Corps and later Project Cadmus. Jim was also an ally of the D.E.O. and his agent Hank Henshaw. Without Jim knowing it, J'onn J'onzz had been impersonating Hank for years.
In 2016, Jim was brought in to deal with J'onn J'onzz's infiltration of the D.E.O.. Jim, along with Lucy Lane, was there to clean up the agency. The two took J'onn, still in the form of Hank Henshaw, to an interrogation room so alien-proof that Supergirl could not listen in. During the interrogation J'onn told the two about what happened ten years earlier in Peru, when he befriended Jeremiah Danvers, which began with the real Hank Henshaw leading a manhunt for an alien who he believed was dangerous. Jeremiah tried to protect J'onn which ultimately lead to the "death" of the real Hank Henshaw.
However, Jim, who was close friends with Hank, as well as having a hatred for aliens for no clear reason, didn't believe him and he was placed in custody. J'onn told Alex Danvers she was next, and likewise was grilled by Lucy and Jim. She explained how J'onn as "Hank" approached her to join the D.E.O. after she was arrested after a DUI, saying that she was special, and that she owed it to her father to be the person he knew she could be. Alex even passed her lie detector test, but Lucy didn't believe her. After Kara discovered earphones so she could listen in, she was stunned that Lucy and Jim were taking the two to Project Cadmus.
After a moment of clarity, Lucy agreed to help Kara. Later that night, as the vehicle was en route, they were surrounded by motorcycles that threw the truck off course. One of the motorcyclists, Supergirl, disarmed the guards, while the other motorcyclist, Lucy, help Alex and J'onn escape, but not before J'onn erased Harper's memory of having meeting him, but not before discovering that Harper had memories of Jeremiah Danvers, alive at Cadmus.
Jim was extremely arrogant, short-sighted, rude, disrespectful, and hypocritical. He also had a strong hatred for aliens, for no clear reason; simply because they were different, regardless of whether or not they were a threat to the human race. He even disliked anyone who associated themselves with aliens, for no clear reason.
Jim was quite immoral, as he helped the government experiment on aliens, violating their civil rights and even violating human civil rights as well.
Behind the scenes
- In the DC comics, James "Jim" Harper is Guardian, a Golden Age hero notoriously known for being cloned several times by Project Cadmus. Harper was previously a police officer in Metropolis' Suicide Slum.
- In the comics, Jim Harper is the uncle of Roy Harper, Green Arrow's sidekick. Roy is a recurring character in Arrow, which may imply that there is a version of Earth-1's Roy Harper on Earth-38.