Grace-093 was conscripted into the Spartan-II program in 2517 when she was singled out as a physically and intellectually superior child by Dr. Catherine Halsey. She was abducted from her home and replaced with a flash clone, then sent to Reach where she was trained with the rest of the Spartans by Chief Petty Officer Mendez and Déjà. She participated in numerous Spartan training missions to Emerald Cove, Chiron Test Station, Military Reservation 01478-B, Military Wilderness Training Preserve, and several others in the Highland Mountains.
She was never actually mentioned by name during the Fall of Reach but was rather designated Red Twenty-Three and assigned to Frederic-104's team by John-117. Their mission was to defend the generators for the orbital MAC guns around Reach. As their Pelican, Bravo 001 was descending to the surface, it was shot down by Covenant AA plasma fire, and their pilot Mitchell was killed. The Spartans were forced to jump to the surface of the planet, gaining many injuries and a few deaths.
Grace was then assigned to "Gamma" team, along with Anton-044 and Li-008. They were sent to evacuate Vice Admiral Whitcomb. They found him but were unable to rally with the rest of the Spartans due to Covenant activity. They then retreated to Camp Independence, where they broadcast Oly Oly Oxen Free and went on hit and run missions for three weeks until they were found by John who recognized the Oly Oly Oxen Free tune. They then proceeded to rescue "Alpha" and "Delta" teams from the Forerunner caves beneath CASTLE Base. Grace then boarded a captured Spirit and went to the captured Ascendant Justice, under control of the AI Cortana.
The vessel then became trapped and ensnared when it tried to jump into Slipspace. The Forerunner Crystal Dr. Halsey found warped Slipspace into an anomalous Slipspace bubble, and several Elite survivors of the ship sabotaged its main drive conduit. Grace was designated Blue-Six during this operation. Despite the rogue plasma and an ambush by the Elites, Grace managed to survive, as did John-117, Frederic-104, and William-043. However, Anton-044, Li-008, and Petty Officer Second Class Polaski did not survive.
OPERATION: FIRST STRIKE
Grace then participated in Operation: FIRST STRIKE. She boarded the Covenant space station Unyielding Hierophant with the other Spartans. However, as they entered a temple, they were ambushed by Brutes. Three rounds from a Brute Shot hit Grace in the stomach, and blew her midsection apart, killing her. John was forced to activate the Fail-Safe Detonation on her MJOLNIR armor, and it self-destructed the armor's fusion pack. She took out four Elites and a dozen Grunts in her "Funeral Pyre." John thought Grace would have liked that.
Personality and description
Grace was the explosive expert among the SPARTAN-IIs. She could shape a charge to cut into a single steel bolt with only a whisper of sound, or rig a hundred thousand litres of kerosene to blow into a "firestorm from hell." Ironically, her temper was nonexistent. It also seems that she liked calamari, a type of seafood.