Grim was a member of the Red Sabre, a pirate organization founded by Torradan ap Dugal that raided the western coastline of Tamriel in the Third Era during the Camoran Usurper's undead crusades against the Septim Empire.
During his time with the Red Sabre, Grim served on Dugal's flagship, the Black Flag. In 3E 267, the Black Flag, along with Grim, was trapped under a cliff during the Battle of Anvil Bay by the mages of Commodore Fasil Umbranox.
Along with the rest of the crew of the Black Flag, including Captain Torradan ap Dugal, Grim survived in Dunbarrow Cove on the rations that the ship had been stocked with for approximately nineteen years. In 3E 286, Grim was the first of the crew to catch an unknown disease and die. He was contagious and passed the disease on to the rest of the Black Flag's crew, turning himself and the rest of the crew into undead skeletons.
His skeleton was not put to rest until 3E 433 when an unnamed adventurer rediscovered Dunbarrow Cove, defeated the skeletons of Grim and the rest of the crew of the Black Flag, and re-formed the Red Sabre.