Theodosius Melhilm Waldstein (テオドシウス・メルヒルム・バルシュタイン Teodoshiusu Meruhirumu Barushutain) works as the "Doctor" for the residents of Waldstein Castle. He lives underground with his colleague and friend The Professor. Originally experimented on by Melhilm Herzog and abandoned by Melhilm as a failure, Theo was mentally unstable and desperate for someone to need him. Eventually he cracked and became a mass murderer, revelling in the act of killing without really comprehending (or even controlling) what he was doing.