The son of Nikolas Apocalypse and Sabrina Schariac, Otto was born in 1452 as a member of House Apocalypse. During his childhood, he met Kallen Kaslana and deemed her as his only friend, vowing together to save the world against the threat of the Honkai. When Kallen's father died for fighting the Honkai, Otto later discovered the 1st Divine Key, Void Archives into hopes of bringing back her late father, which he ended up reconsidering as her father's sacrifice will be in vain. This Divine Key would later assist him in his later goals.

Afterwards in his adulthood, Otto became the next Overseer of Schicksal (specifically the 227th), securing the position for the next 500 years in his own callous obsession of finding ways to revive Kallen. In one of his cloning attempts, he created Theresa Apocalypse and would later adopt her as his granddaughter.