Dieter has shaggy blond hair and light bluish-gray eyes. He wears the typical uniform of the Scout Regiment.
Dieter appears very unconditioned and mentally cracking. He shows great distress over the death of his friend Ivan, and disobeys his superiors when they refuse his request to retrieve his body; resulting in the death of his friend Jurgen. When confronted by Captain Levi Dieter bursts into tears, cracking under the mental stress he had endured. Though he shows passion for his friends, this passion manifests itself in the form of recklessness resulting in comrades deaths.
During the 57th expedition, Dieter, along with his friend Jurgen, argue with Erwin and Levi after they refuse their request to retrieve the body of their dead friend, Ivan. Erwin decides to abandon all the bodies they were unable to retrieve and list them as "missing". Dieter and Jurgen angrily act against this command and retrieve the body of their friend, and in doing so, lure several Titans to the Scout Regiment's position. When a Titan swings at him, Ivan's body falls off Dieter's horse and is lost.Right after, Jurgen is grabbed off his horse and despite Dieter switching to his omni-directional mobility gear in an attempt to save him, Jurgen is eaten right before Dieter is grabbed by a Titan. He is about to be eaten before Mikasa Ackermann kills it, saving him. Due to the Titans being drawn towards them, the Scout Regiment are forced to dump bodies weighing down the carts in order to escape. After this incident, Levi confronts Dieter and hands him a Scout Regiment badge saying it was Ivan's, causing Dieter to break down into tears. He is last seen on one of the carts returning to Wall Rose, holding the badge in his left hand with his head down.