Dr. Liam Grant is perhaps the most mysterious member of the team in terms of his past. Much of his life previous to joining SG-2 is a shroud of shadows and webs. Originally he was with the NSA as a non-official "hit man". A mission occurred, however, that forced him to make a terrible choice, and it all but ended his career and almost his life. He left the NSA in a "retirement" and as a civilian pursued his hobby of archeology.

Grant was finished with the government for good; Or so he thought. The Airforce had other plans. During his time as a civilian, he had earned a doctorate in Ancient cultures. With this combination of knowledge and his past experience with NSA, the Airforce asked him to join a top secret Stargate project. Not wanting to be involved with the government, Grant joined reluctantly.

Dr. Grant was initially assigned a desk job at the SGC, analyzing artifacts and data that was brought back by other SG teams. The value of his past experience mixed with his current knowledge was quickly realized and he was immediately assigned to SG-2 as its lead translation and cultural integration expert.