Rellus Tagrim was a Takret male who, along with Guri and Renth, had served in the lower ranks of the Takret Militia until he realized the corruption among their commanders. The three of them attempted to resign their commissions, but when the militia refused to allow this, they deserted rather than continue serving within an immoral military.
While fleeing the Militia in a small vessel in 2152, Tagrim and his comrades encountered the Earth Starfleet ship Enterprise. In an attempt to hide from the Militia, Tagrim requested that he and his men board the Enterprise. Fearing that the Enterprise would not assist them if they knew they were deserters, he used an approaching neutronic wavefront as an excuse, even though Takret physiology was immune to the radiolytic isotopes which the wavefront emits.
Upon boarding the Enterprise and enduring a wait in the ship's decon chamber, the Takret are welcomed aboard Enterprise by Captain Archer. Tagrim claimed that he and his men were stellar cartographers. Unable to outrun the wavefront, however, the Enterprise crew must gather within the ship's warp nacelles to prevent exposure to the wavefront's isotopes. To keep up their ruse, Tagrim and the other Tekrit wait out the wavefront in one of the nacelles, as well.
Unfortunately, the Takret Militia were able to detect the deserters' vessel in Enterprise's shuttlebay, and boarded the starship while it was engulfed in the wavefront. Although Tagrim tried to prevent him, Guri exposed Tagrim's lie, forcing him and the others to explain themselves. Although the Takret captain and his crew laid claim to the vessel and reinitiated the ship's warp reactor, the Enterprise officers were able to drive them away by steering the ship towards a plasma eddy within the wavefront. After the Enterprise clears the wavefront, Tagrim and his comrades were allowed to leave for the Gyrannan system, where they hoped to be safe from the Militia. (ENT: "The Catwalk")