Severian Marcella was arguably the second most important figure in the founding of Seleucar. He shared a childhood with Nikolas, and often bullied him into giving up food - an act he admitted later on with shame. Years later, he accompanied Nikolas on his travels, providing a cynical foil to Nikolas' lofty optimism, and engaged him in such debates as the so-called "Sermon on the Rocks." Eventually, he gave in to Nikolas' idealism, and when the young man became Nicator and his burgeoning village branched into a bustling capital, Severian was appointed as the duke and later chancellor of Seleucar - the right hand of Emperor Nicator himself. He outlived Nicator, but passed away mere years before the War of the Deeps came to fulfill the prophecy of the Black Wave.
Severian now assists with the Trial of Rebirth on the plane of Ceylon by teaching new adventurers basic knowledge about themselves and others.