Lords of the Underworld

Long ago, twelve immortals warriors – each more dangerously seductive than the last -- stole and opened Pandora’s box, unleashing the evil from within. Now they carry that evil within themselves. Violence, Pain, Death, Disease, Disaster, Misery, Doubt, Promiscuity, Defeat, Lies, Secrets, and Wrath. When a powerful enemy returns, they will travel the world in search of a sacred relic of the gods – one that threatens to destroy them all. 

Things of note: 

~The true first novel in this series is The Darkest Night.  

~The Darkest Fire is a short story prequel, and does not need to be read to understand the series.

~The three chapters of the story, Awakening Pandora, fond in the book Into the Dark, was Gena's first attempt at writing the Lords of the Underworld and will never be completed (so Maddox will never end up with Farrah :)