Before his arco-flagellation he was a human male named Erin Octavus, a grox farmer native to the Agri World of Standalone. A sufferer of the Gathalamor Syndrome, a condition in which subjects become determined to sacrifice themselves in the name of the Emperor, Octavus believed he was tainted by evil. After several attempts to placate and purge the farmer failed, Octavus, spurred on by his hallucinations, attacked Cardinal Simeon for which he was tried and sentenced to Arco-flagellation.
Octavus, named as Simeon 38X after the Cardinal that condemned him, still suffered from Gathalamor syndrome (it was speculated that his pacifier helm actually worsened his condition), which resulted in him not always responding to his trigger word, Exculpate. On a number of occasions this resulted in bloody consequences, most notably during his service to Inquisitor Steinbeck. Following the grisly death of several members of the Ecclesiarchy, Simeon was almost terminated. Witch Hunter Tyrus intervened, granting him a stay of execution. Simeon was given a re-trial and sentenced to "deathmasking." After this, he was held in stasis aboard Tyrus's own vessel, a ready instrument to be unleashed upon the witch hunter's most hated foes.