Marcellus is the name of Luka’s father. He had slain Alice the XV (Fifteenth), the previous Monster Lord, along with Lazarus and two others, but realized her intentions for coexistence too late. Just as he and his companions were proceeding to spread her wishes, Alice the XVI (Sixteenth) came along and attacked the group out of blind rage. Having killed Karen, a woman whom Marcellus and Lazarus loved, they founded Ilias Kreuz out of vengeance. However, when Marcellus begun assisting monsters and having betrayed the ideals of the organization, Lazarus executed him and placed a guise that he was killed by monsters.
Luka was originally aiming to become a martyr because of his father, under the belief that Marcellus was a crazed terrorist and Luka would rather die than lose his way.