While he was young, Sulfur was a very happy and loyal child, refusing to kill his adoptive father when discovering that he supposedly killed his father, and aspiring to become a great captain after him while trying to forget killing him. Upon rediscovering his memories of his home, the attack of his village and discovering his parent's true murderer, Sulfur suffered a mental breakdown and became known for being very aggressive and depressed, having created a second personality to keep himself from panicking when pressured.[19] Only after reuniting with his father, marring Alice and having a son did he became calm and kindhearted.