Glen Reiner was a member of the Special Survey Unit, a branch of Shinra Electric Power Company's military, who suffered from mako poisoning. He appears in Final Fantasy VII Remake: Picturing the Past.
Glen Reiner gew up in the Midgar slums. He made friends with two other military members, Joann Liu and Lilisa Meg, as well as a Shinra clerical worker named Geddie Bach. Glen and Joann joined the Special Survey Unit, a classified task force that located mako reserves from landscape pictures Aerith drew. Though the job paid well, mako-handling techniques were rudimentary, leading to a relatively high rate of mako poisoning among the employees.
Glen was assigned to search Cosmo Canyon. Lilisa threw a party for him and Joann before the two departed. However, Lilisa became upset and begged Glen not to go, confessing romantic feelings for him. Joann stepped away from the party and, upon her return, found Geddie, Lilisa, and Glen all very ill. Geddie theorized that Lilisa had drugged their food with mako. While Glen and Lilisa remained unstable, Geddie took on Glen's identity, ostensibly to complete the SSU mission and achieve Glen's dream in his stead. In actuality, Geddie had drugged the others so that he could take Glen's place and gain favor with President Shinra.
Lilisa recovered somewhat but Glen succumbed to the mako poisoning. As per Shinra protocol, his family was told he had died in the Wutai War. Lilisa never returned to her former self, and at one point attempted to strangle Aerith, blaming her for Glen's death. Some years later, Glen's father found him wandering around the slums and brought him home. Glen, along with Lilisa, Geddie, and others, had begun to wear black robes, had numbered tattoos, and instinctively gathered together in Midgar.