While most of his life is unknown, Epsilus is rumoured to have lived since the days before the Heresy. Said to have been amongst the first recruited after the discovery of Alpharius, he was commended for his initiative and unorthodox strategies – at least by the Legion. What little information remains from his days serving the Imperium denotes him as a trouble maker and habitual loner. It is rumoured that he took command of his company after the death of Captain Iotus during the heresy at the hands of the Salamanders Legion, though few records exist to prove this.