Haran Serpens was a well known Magos Biologis, a Tech-adept of microbiology and cellular replication within the Adeptus Mechanicus. After his untimely death, his identity was usurped and used as an alias by Fabius Bile for a variety of purposes, such as trading with unsuspecting counterparties, and, in a notable instance, to confound and corrupt Apothecary Majoris Caecus of the Blood Angels Chapter. Bile thus managed to set foot on the Blood Angels' homeworld of Baal and steal a vial containing the blood of the Blood Angels' Primarch Sanguinius. Bile planned to use the genetic information stored in this sacred relic of the Blood Angels Chapter to pursue his continuing quest to create more perfect Astartes than the Emperor.