Berstetz is a very old man of short stature. He has relatively long grey hair that is tied back with an aged and wrinkled face. Underneath his slightly crooked nose, he sports a bushy mustache. Despite his position as the Imperial Prime Minister, Berstetz can be seen wearing a rather humble and every-day long-sleeved attire.
Berstetz is a very wise and shrewd old man who's is easily able to outsmart people. He also appeared to be very loyal to the Emperor, working behind the stage in order to eliminate any and every threat that's facing Vincent, as well as leading the Empire when Vincent isn't able to, as seen during the events of Ex4.
Having said that, Berstetz seems to have more going for him than what meets the eye as Vincent himself seemed to be aware that something's off with the old man.
During the Imperial Selection Ceremony, Berstetz acted under Lamia Godwin's command, helping her achieve her goal of slaughtering every single one of her half-brothers and half-sisters in order to be crowned as the 77th Emperor of the Vollachian Empire. During the battle at Abellux Manor, Berstetz helped to command the army led by Lamia by controlling the artillery on her behalf. After Lamia realised the battle was lost, she ordered him to cover her retreat. Following Lamia's death and Vincent's coronation as the 77th Emperor of the Vollachia Empire, Berstetz started working under him and was eventually appointed as the Imperial Prime Minister, granting him political strength second only to the Emperor himself.
Six months before the events of Arc 1, two members of the Sage Council, Miklotov McMahon and Bordeaux Zellgef, accompanied by Reinhard van Astrea, Julius Juukulius, and Ferris, chose to go on a diplomatic visit to the Empire in order to sign a non-aggression pact between the Dragon Kingdom of Lugnica and the Empire. While not immediately meeting with the five diplomats, Berstetz acted in the shadows, swiftly getting rid of the traitorous noble who planned the coup d'état during the aforementioned diplomats' visit in the Empire, effectively keeping the rebellion at bay.
Two to three months after this, Madelyn Eschart was suggested by Berstetz to inherit Balleroy Temeglyph's position as the 9th ranking Divine General despite not having any concrete accomplishments and being largely unknown to the other Divine Generals. After Yoruna's rebellion, his suggestion was confirmed and Madeline was appointed as the 9th ranking Divine General to the reluctance of the Emperor.
- "Hmph. And to think, I very nearly had the tiger by the tail" Re:Zero Ex Light Novel Volume 4: Diplomacy by Bloodshed. Section 19.