Melkhior was a Necrach Vampire and a disciple of Wsoran, the first of the Necrachs. It is therefore likely that Melkhior was once an acolyte of Nagash and was turned vampire by Wsoran. After fleeing Nagashizzar when Alcadizaar had assassinated Nagash, Wsoran and his fellow men, including Melkhior, went into hiding to study Necromancy.
One of Wsoran's finest and most diligent students, Melkhior seized one of the moments in which his master's soul travelled the spirit world to betray and kill Wsoran. Some say it was the Book of Nagash, given to Wsoran as a reward, which wispered Melkhior to do so, though his true motives are unknown.
The next that is known of Melkhior is that he lived in a hidden tower in the Forest of Shadows in the Empire where he caught Zacharias redhanded while the Necromancer was sneaking into his tower to steal the Book of Nagash. Melkhior granted the Blood Kiss to the thief, turning Zacharias into a vampire and his pupil for the following years.
Melkhior taught Zacharias everything he knew but never let his student near the Book of Nagash. Melkhior, however, was keen on indulging in "bloodfests" coinciding with fits of insanity. On one such moments, Melkhior returned to his study to find Zacharias reading the Book of Nagash. Melkhior attacked, but Zacharias escaped. He then sent out his dark servants to hunt down Zacharias, who remained out of his grasp.
One day, Zacharias returned to Melkhior's tower on the back of a great Zombie Dragon. A great battle ensued. No-one knows what the result was, some say Melkhior was killed, other say he escaped and hides, plotting his revenge, but the Book of Nagash and the magical wealth that Melkhior had acquired fell into Zacharias' hands.