Tercorien was a doctor working in Washington, who was drafted into the army just prior to the Great War. Much to his dismay, he was shipped to Anchorage, Alaska, after receiving training in cryoscience. Attached to the 108th Infantry Battalion, he and his team were responsible for patching up soldiers wounded in combat with the Chinese.
It was there that he and his medical team were abducted by Mothership Zeta. Only two other members of his squad survived the experiments until the Lone Wanderer found them. They were kept frozen separately near what appears to be a surgery with the rest of his squad's bodies. If the player revives the other two squad members before Elliot has had time to restore their memories then they become hostile. Elliot can either put them out of their misery or revive them. If they are revived, they only have a limited amount of time before they die.