Captain Demian Brackett was a member of the United States Colonial Marine Corps. He was commanding officer of the unit stationed at Hadley's Hope on Acheron in 2179. He was subsequently involved in combating the Xenomorph infestation at the colony.
Brackett is mentioned in the Weyland-Yutani report, he gives testimony on how long a Facehugger can live for.
Demian was a former paramour of Anne but despite this history, maintained a friendly demeanor to both Anne and Russ. Demian was professiona and moral, constantly at odds with the Weyland-Yutani staff at Hadley's hope. Demian was shown to be practical and believed in being cautious and prepared.