Sergeant Major of the Trooper Corps was a unique non-commissioned rank and billet in the Twilight Trooper Corps. The holder of this rank and post is the senior enlisted member of the Corps. They act as senior enlisted advisor to the Supreme Commander.
The Sergeant Major of the Trooper Corps, acts as a bridge between Enlisted personnel and Commissioned personnel in the Corps. They directly report to the Supreme Commander, the High Ranking Templar who commands the whole Corps. They reported on things like morale, trends with enlisted personnel, and other things related to the Enlisted command structure. They did things that a Normal Sergeant Major wouldn't concern themselves with, this applies to the Sergeant Major of the Marine Corps and the Master Chief Petty Officer of the Navy as well.