Castellian, his username formerly being Brickster1324, was TGI's previous leader, before he passed on the leadership to ToberDam right before the VAK-TGI war began. On November 2nd, 2013, he regained leadership of TGI for a while. Later, however, the group's leadership was handed over to rodgerdodger.
Before becoming Castellian, Brickster1324 was a Vaktovian Colonel, who was a high ranking official in the very controversial Vaktovian Military Police, and was also a member of the Grey Knights. He along with many other people brought Vaktovia into a dark age before finally retreating to his own rogue group - The Grand Imperium. He contributed to this Dark Age with taking out Political Enemies of his regime using the VMP; deeming them corrupt as the excuse to exile them. He also helped formulate the ideals of divisions within the group, causing the group to split into many sub-factions. He left eventually, taking many men with him and aligning themselves with the Roblox Assault Team, leaving Vaktovia in a devastated state for a very long time.
Before the Dark Age
Castellian was actually a very good soldier and leader of troops. He fought in multiple battles against R.A.T and other enemies of the empire, and could be usually found with Toberdam and Tainteddark. All three of these individuals were exceptional in combat and leadership roles, and excelled through the ranks. Using their prowess these three actually did some good for the empire before becoming traitors to the people of Vaktovia.