Grace Harper is one of the main protagonists of Terminator: Dark Fate. She is a member of the human resistance against Legion, an artificial intelligence that has waged war against humanity in the future. Having been cybernetically augmented into a super-soldier, Grace has been sent back in time on a mission to protect Dani Ramos, the future leader of the resistance. She is portrayed by Mackenzie Davis.
Grace was a child when Judgment Day occurred in 2023. The cyber-warfare program known as Legion had spread itself across all global civilian infrastructure and shut down all power grids, bringing human society to a standstill. In the years to come, Grace witnessed many atrocities as billions of humans died, whether they were hunted by Legion or killed each other over what little food was left. However, she was saved by a woman called Daniella Ramos who took her in and rallied several other survivors into forming a resistance movement against Legion.
In 2042, Grace was serving as a Resistance soldier and was involved in the rescue of a high-ranking officer. Following this mission, she volunteered for the Resistance's augmentation program and underwent extensive cybernetic modification. The procedure resulted in Grace obtaining superhuman strength, agility and reflexes, though she would require regular injections of a particular medical concoction in order to remain functional and a miniature thorium reactor implanted within her would maintain her cybernetics.
At some point, the Resistance captured a time displacement device which Legion had used to send a Rev-9 Terminator back in time to kill Dani Ramos before she could form the Resistance. Grace volunteered to be sent back to protect Dani, and so she was sent to Mexico in 2020. Upon her arrival, she was helped by a young couple before she attacked a group of policemen who tried to take her from the scene. Grace then took clothes from the man who helped her and left the area with the couple's car.
She managed to find the young Dani Ramos and her brother Diego Ramos in the factory where they worked. She rescued them from the Rev-9, but Diego was killed by the machine during the ensuing highway chase. Sarah Connor arrived the scene and saved them, but Grace stole her car to take Dani away. They were reacquired by Sarah outside a drug store after Grace crashed due to the intense battle with the Rev-9.
Later, Grace recovered with Sarah's help and explained who and what she was. Reluctantly, she accepted Sarah's help in protecting Dani. After learning the location where the mysterious texts sent to Sarah were coming from, which were the same coordinates tattooed on her belly, Grace and Sarah decided to travel to Texas with help from Felipe Gandal and his son Flacco, only to be attacked by the Rev-9 with a UAV drone before being arrested by the United States Border Patrol. After escaping the detention center, they arrived at the coordinates, only to find it was home to Carl, a CSM-101 Infiltrator, who was responsible for the death of John Connor, Sarah's son.
Carl agreed to help the women as he believed in fate, considering Sarah's action to destroy Skynet had set him free. After acquiring two EMP generators from Major Dean, they were attacked by the Rev-9. With Dean's help, they managed to board a C-5 cargo plane after the Rev-9's pursuit and attack, which destroyed the EMP generators.
They were attacked again when being attacked by the Rev-9 in its hijacked aerial refueling aircraft. After the battle, they escaped the plane in a Humvee and landed in a hydroelectric dam. After regrouping with Carl, Dani called the ground as their kill box against the Rev-9.
During the final battle against the Rev-9, Grace was severely wounded and unable to continue fighting. While Carl was able to force the Rev-9 into a turbine and destroy its polyalloy shell, its endoskeleton recovered and emerged from the wreckage. Grace urged Dani to remove the thorium reactor in her abdomen and use it to overload the Rev-9's CPU. Dani was hesitant to do so, but Grace assured her that it was the only way to stop the killing machine. Dani used a shard of metal to cut open Grace's midsection, then pulled out the thorium reactor. Without the reactor maintaining her implants, Grace succumbed to her terrible injuries and died.