Matteus is considered one of the five great commanders of the Imperial Army of Erebonia, the others being his brother Zechs Vander, Victor S. Arseid, Aurelia Le Guin and Wallace Bardias. Matteus is rather untalkative, saying no more than needed, and always wears a stern expression, making him misunderstood by those around him. However, those who actually know him are deeply attached to him.
Days before the signing ceremony for Crossbell's re-independence, he started to behave oddly, like contacting Claire Rieveldt of the Railway Military Police and providing his students with instructions.
- Matteus holds the title of Viscount.
- It is unknown what happened to Matteus' first wife who is Mueller's biological mother.