Darius is a member of the ancient semitic race of shape-shifters known as the djinn. When he is touched by a human, it ignites a psychic conduit that bombards him with that person's deepest desires and urges, sexual and otherwise. Once privy to these unspoken longings, he is compelled by deep-rooted instinct to turn them into reality.
Maddened by this need to fulfill the secret appetites of others, which makes him feel like a slave to every human he encounters, Darius has become the most solitary of the Grotte Cachée follets. He lives not in an apartment of the chateau, like the other three, but in a private chamber deep within the cave, where he has amassed a vast collection of old and rare books. In order to avoid human contact, he prefers to go about at night rather than during the day.
When he does find himself in the company of humans, he frequently takes an animal shape, usually that of a dark gray cat or a blue rock thrush. He also has the power of invisibility, to which he resorts from time to time. Darius is incapable of lying to humans, but he can refuse to answer a question.
There is much about Darius that is shrouded in mystery, given how taciturn and reclusive he is. His precise age is unknown, although it is likely that he is the oldest incubus at Grotte Cachée. He fled his homeland, somewhere in the near East, more than two thousand years ago, probably closer to three, for reasons that he has never shared with me or any of his past gardiens. At some point in the last few centuries BC, he took up residence in our hidden grotto, where he was safeguarded and shielded by the druids who came before me. Darius is dark and brooding in both appearance and temperament. Unlike Elic, Lili, and Inigo, who are susceptible to fire, he can only be killed by drowning.
From the Histoire Secrète de Grotte Cachée by Adrien Morel,