When Ernest felt the indifferent gaze of the masked youth on him, for the first time since the war against the undead, he felt fear for his life.
Demons and undead are allies but they also only worry about their own kin, Falco worked for the best alchemist among the undead race, the so called "mad alchemist", a well known but at the same time mysterious powerhouse.
The mad alchemist earned its tittle because its research is centered in using live subjects to create potions, poisons, pills and even consumables.
For example, the poison which Ernest wanted to buy "gray death" required gray matter of the brain from an Arch ranked human and an Arch ranked demon.
Which means he offends both enemies and allies by equal, that's why its identity is a secret, that being said the products created by him are of a high quality, and since the specific ingredients are a secret, then his buyers turn a blind eye at his actions.