Thompson is a mage of respectable power and less than respectable stability. He is a diviner, and like many diviners, he is a bit of a paranoid loner.
During the Empire-Avernum War, he lived in Blosk, where he worked with another mage, Bartholemew. The Tower of Magi had tasked them with finding new coordinates for the portal. Thompson developed a special technique for finding coordinates using astral projection.
Soon afterwards, he stumbled on the coordinates for Garzahd's fortress. Thompson became convinced that Garzahd detected him and was trying to kill him, to keep the coordinates safe. He fled to a Scimitar cell in Fort Remote, locking himself in a room, the key to which he deposited inside a doorless room in the ruins of the Nephilim Castle far to the northeast.
Thompson eventually revealed the coordinates to the Empire War Heroes. He has remained at Fort Remote since then. Although he is in a less-than-stable state, he continues to conduct research on behalf of Avernum. During the Vahnatai retribution, he researched Vahnatai pylons.