He is later revealed to be a rebel and spy, implanted into the Galra Empire ranks while spying for the Blade of Marmora, a secret group of Galra rebels who are against Zarkon and his tyranny.
He later sacrifices himself to save Keith and cause the power core of Zarkon's ship to overload and explode.
Due to his limited screen time, much of Thace's personality can only be discerned through his actions.
As one of the spies of the Blade of Marmora, Thace is dutiful soldier, dedicated to the downfall of Zarkon and commits himself solely to his duties. A sign of his immensely disciplined mind is his ability to activate his luxite blade, which can only be achieved by Galrans of immense willpower and humility. Due to his role as a spy, Thace is calm, collected, and incredibly observant, being one of the top-ranked moles within Zarkon's ranks. He seldom emotes more than his orders, and he is a level-headed individual.
Thace is also a rather intelligent individual, able to deduce Keith's Galran heritage by how he was able to wield a Marmoran luxite blade.
Thace is ultimately characterized by his unselfish and self-sacrificing nature, putting himself in constant risk for his cause, and in the end willingly gave up his life in order to see the end of Zarkon's reign despite Keith's protests for him to leave with him.
Due to his role as a spy, Thace was an expert in subterfuge, sabotage, computer hacking and communications, deception, and more. As an agent of the Blade of Marmora, Thace was also a master swordsman, able to activate his blade even when not in direct contact with it, such as when he freed himself from captivity by awakening the sword through sheer willpower to cut through his restraints. Thace was also highly resistant to torture and interrogation, suffering from days of relentless torment and electro-torture from Haggar and her druid underlings without cracking. He was practically fearless, and rigged the central control room of Zarkon's flagship and base as a bomb, dying with a smile on his face.