Milieus Zeremski was of average height with bluish gray eyes and ash blond hair. He wore the typical uniform of a members of the 104th Cadet Corps.
Milieus seemed shy and cautious; he warned Eren when he was running off to avenge Thomas Wagner for fear of his safety and inexperience. However he showed bravery when charging in with his squad to save his comrade.
Milieus is among the members of the 104th Cadet Corps during their three year military training period.
Milieus graduates training as a member of the 104th Cadet Corps. After the second attack of the Colossal Titan, he is assigned to a middle guard squad in Trost District with Eren Jaeger, Armin Arlelt, Mina Carolina, Thomas Wagner, and Nack Tierce.Shortly after the squad's deployment, the group is attacked by an abnormal Titan, which results in the death of Thomas Wagner. This causes Eren to attack the abnormal in a rage. Milieus warns Eren not to go alone, but he does not listen and a Bigmouth Titan bites his leg off which in turn causes his squad to pursue it to try and help him. Milieus is caught and eaten by the Titan, Nack Tierce gets swatted by a Titan midair, while Mina Carolina is knocked against a wall when a Peering Titan grabs her wire and then eats her. Armin can then only watch as fellow cadets are caught and eaten by the Titans.
Armin later reports Milieus' demise to the remaining members of the 104th Cadet Corps, saying he died valiantly in the line of duty.