Private investigator, monster hunter, frequent customer of bawdy houses (a little less so lately), and part-time apocalypse-causer, Kaine has been a fixture of his neck of Waterdeep for over a decade, operating as Mystic Eyes Investigations. Before that, he did other things, for about 262 years. Kaine is immortal, thanks to his devilish bloodline. He was born in Ascalhorn, and was present for its fall (partially his fault). His father sold his soul, and that of his two sons, to an infernal overlord. Kaine never consented to anything, and so inherited some of his father's fel powers, but no allegiance to his dark lord. Still, he operates under the assumption that he is inevitably damned, if not for his blood, then for his inumerable venial sins (and a good number of mortal ones), most of which are ways of appeasing his infernal nature and keeping it at bay, but some are just for the fun of it.

Orphaned at an age too young to remember her parents, Helena had a rough start amongst the orphanages of the city, before being taken in by a kindly old gnome, who stoked her interest in Artifice and engineering. Kaine aided the gnome in an investigation, and returned frequently to upgrade his equipment. He became something of a heroic figure to Helena (who, since leaving the orphanage, has insisted on using her middle name, which we'll do from this point), who dreamed of joining him and his mysterious, stoic friend on their grand adventures.

In her early teens, her adoptive father became ill, and before he passed, he secured a promise from Kaine to care for her. And so, Penny shacked up with Kaine, who insisted she would be studying and learning, not adventuring. He continued insisting, as hard as possible, until inevitably she overpowered him and became a full member of the Mystic Eyes. She continued operating in this capacity until recently, when her entrepreneurial duties became too overwhelming.