Black City Demon — Richard A. Knaak

Since he became the guardian of the Gate between our world and Feirie sixteen hundred years ago, Nick Medea, once Saint George, has battled to keep the darkest Feirie--the Wyld--from invading the mortal plane. With the dragon an unwilling part of him, Nick maintains balance between realms, often at great cost to him and those nearest to him.
    
Nick and his ragtag confederates--including the shape-shifter Fetch and Nick's reincarnated love, Claryce--have battled the Wyld, but mortals as sinister as the darkest Feirie. Now, with Prohibition in full swing and bootlegger wars embattling Chicago, a murderous evil born of the mortal world has turned its attention to the power of the Gate...and Nick himself.
    
Nick must turn again to his most untrustworthy ally: the dragon within. Yet even together they may not be enough to face what was once a man...but is now a creature even dragons may fear.