|It's natural to feel some doubts sending hundreds of troops to their likely deaths when the core of the strategy is uncertain, but I can understand where Commander Pixis is coming from.|
|— Gustav empathizes with Armin's concerns|
He is a tall young man with a solid build. He has combed black hair and dark brown eyes. He wears the typical Garrison uniform.
Gustav is portrayed as a stern, quiet individual. He seems respectful to his fellow soldiers such as Armin Arlert, which can be seen when he listens to his plans and takes his opinion into consideration.
Gustav is one of Dot Pixis's escorts, and is present when Pixis stops Eren Yeager from being executed. Pixis creates a team to formulate a plan to recapture Trost, and Gustav is included in the team. He hears out a plan from Armin and points out its risks, telling Armin that if the central part of the plan remains unknown, then they will essentially be leading soldiers to their death.
He is later seen reporting to the commander about the soldiers who had been "lost" during their mission.
Gustav is accompanying Pixis when the advance unit reports back that there is no breach in the Walls, and informs them of Reiner Braun and Bertolt Hoover's true identities as the Armored Titan and the Colossus Titan.
Gustav attends the trial to determine Erwin Smith's fate alongside Pixis. When Anka falsely reports that the Colossus and Armored Titans have breached Wall Rose, Gustav begins to mobilize with the rest of the Garrison, only to be halted by the royal officials present, who order that all refugees be barred from entering Wall Sheena. He then watches as the officials are forcefully detained by Darius Zackly's forces.
After the assassination of Darius Zackly and Eren and his followers' defection from the military, Gustav accompanies Pixis as the commander attends a meeting to suggest surrendering to the "Yeagerists" for the time being.