Clause grew up alongside Kasel and Frey in an orphanage, forming a bond that established him as Kasel's adoptive older brother and ignited his protective instincts. As a knight of Orvel, he stands on the front lines, specializing in defense. His ability to withstand enemy attacks and shield allies earned him the title "Knight of Iron Defense," his defensive skills often compared to an unyielding castle wall.

Despite his reliability and combat prowess, Clause holds a low rank within the knightly order. He prioritizes protecting his homeland and its people over pursuing personal wealth, status, or recognition. His dedication stems from a deep desire to safeguard Orvel, the place where his most valued relationships began.

His protective nature focuses intensely on Kasel. When demonic activity surfaces near Orvel, Clause volunteers for reconnaissance on the King's Plains. During this mission, investigating demonic threats on the Gallua Plains alongside Scarlet's expedition, he is reported missing. This disappearance spurs Kasel and Frey to search for him.

Clause later reappears, fighting against the resurrected Dark Lord Angmund. In the final battle, he provides critical defensive support, holding the line against Angmund's forces to create an opening for Kasel to confront the Dark Lord, enabling Kasel's victory. Following Angmund's defeat, Clause chooses to remain stationed in Orvel to continue his knightly duties while Kasel and their companions journey onward, underscoring his unwavering commitment to his homeland.

His fierce loyalty sometimes conflicts with his faith. He resents Lua, the goddess of light, for assigning Kasel the perilous destiny of becoming the holy sword Eia's successor. This internal struggle reveals the depth of his protective feelings for Kasel, pushing him to question divine will.