" The spider carried the larvae as they developed, and they in turn altered its behavior, causing it to change the webs that it spun, so that when the larvae finally erupted from its body they would have a cushioned web upon which to rest while they fed on the remains of the arachnid in which they had gestated. Epstein had told me that there were entities who did the same to men—dark passengers on the human soul, carried unawares for years, even decades, until it came time to reveal their true natures, and then they consumed the consciousness of their hosts. "

― John Connolly , The Wrath of Angels (Charlie Parker, #11)