Not much of Reed's background and early life are known, as his file has been heavily redacted. It is known that he was in the military & worked with several international task forces on multiple occasions, including one based in Italy during the Firstborn's reign of terror in the region as "Il Primo". Firstborn slaughtered Harrow's teammates and the ambassador they were assigned to protect, Franco Giorgetti, before stealing Harrow's US Army dog tags after a heated one-on-one battle and fled.
Harrow relished the chance to pursue the Firstborn again with the SCT after his performance in an operation dubbed "The Brixton Bloodbath" caught their attention. He became an important part of the squad & a close friend of Agent Boone Ligaya, whose death seems to have traumatized Harrow the most & caused a strong bond to form between him & Forensic Specialist Kai Kalaba, who was said to remind Harrow of Ligaya. Though implicated in the bombing of the SCT's aircraft and later accused by his partner, Jeremy Redbird, of being the Firstborn himself, Harrow eventually earned his new team's trust. It is revealed through flashbacks that he continued investigating the Firstborn on his own, who had been toying with Harrow in a similar way to Det. Blaise Corso since the encounter in Italy.
His identity was stolen by Firstborn in order to infilrate the SCT and their headquarters at Alcatraz Island. Though he did not physically participate in the stopping of the Firstborn's plans, his warning call to Kai Kalaba and Data Analyst Amy Chen helped to destroy the electromagnetic interference set up by Kingfisher to stop police interference with the plotted Nightmare attack.
In V14C4, the SCT discovers while searching a possible safehouse of the Firstborn a series of photos. The photos are traced by Amy Chen to be of "Lilith Collins", an entity who went missing from Pasadena, California (located 400 miles away) two days prior. While Reed, Emma and Boone are on the plane (as Natara couldn't come since she was attacked by bikers), they recieve a call from Natara -- she tells them that Firstborn likely planned for an attack on the plane. They manage to find a bomb, and Boone disarms it; but 4 mroe bombs are revealed to be there. The bombs then detonate and explode in the plane.In the bonus scene, while searching the crime scene on the ground after the sky-explosion, Kai explains that 17 bodies were found dead whilst 22 were confirmed to be on the plane. In the bonus scene of V14C5, the sole survivor is revealed to be Reed, who is shown in a hospital, recovering from minor injuries. Lt. Charles Anders debriefs him, which further reveals that Reed was the only one on the plane who had a parachute, thus casting greater suspicion on the circumstances of his escape.
The suspicion only grew when Kai Kalaba, searching for Boone's killer, was seen attempting to stalk him in Volume 14 Chapter 7. In Volume 14 Chapter 8, Part 1 of the volumes finale, it was revealed that Reed was infact not the Firstborn as while saving Kai Kalaba's life from a killer, Mal and Natara were being watched by the real Firstbron on a boat. After saving Kai, the pair shook hands and called a truce, for now. His later appearance in V14C9's bonus scene seems to clear up doubts that he is the Firstborn, and he acknowledged being one of the best friend's of Boone Ligaya.
Reed has since then relocated in London together with the new SCT team in Volume 15, comprising of Mal Fallon, Natara Williams, Jeremy Redbird, Amy Chen and Kai Kalaba. He then assisted in their Japan investigation in Volume 16, though the Firstborn -- who acted as his imposter and used plastic surgery to reconstruct his face -- had his assistant shoot Reed in the forehead and dumped into the ocean. Reed was barely able to stay alive, but revealed in the series epilgoue that even though he is now no longer suitable for combat duty, he plans to find another carrer (with his fluency in 7 languages and functionality in another 12), perhaps as a high school teacher.