Gurran Schmittel, a scientist within the Secret Society faction, operates under Albert Killy's command, researching the creation and development of Perfect Soldiers. He consistently collaborates with his twin brother, Aaron Schmittel, on these scientific projects. Gurran is distinguished by his green attire, contrasting with Aaron's brown clothing. Their work centers on the genetically engineered Perfect Soldier Ypsilon, whom they treat with near-reverence as a demigod due to his enhanced capabilities.

The Schmittel twins engage in covert operations involving Ypsilon, including observing his battles against Chirico Cuvie on Sunsa. Later, they accompany Killy to Quent, becoming increasingly absorbed in uncovering the planet's secrets, particularly those concerning advanced human evolution and the legacy of the Overmen. During this period, Aaron develops greater personal ambition, while Gurran remains more aligned with their original scientific objectives under Killy's direction, showing less individual initiative. Both primarily fulfill roles of technical support and data analysis within military-research contexts, rather than combat or leadership.