Cassie had been born into a world that was already decided for him, his destiny already laid out and his place in the world already marked. When he was born his mother had been made to be the host for Shub-Niggurath which had caused her to die during the childbirth, Cassie's father Toah-ken found this troubling but found solace in that this was a mere pebble in the grand canyon that was the future of the tribe.
Cassie had grown up relatively well, living the normal life of a native boy despite his rather feminine appearance. On his eighteenth birthday, he was put through a trial to prove his devotion to the path he was set on, to kill his entire tribe. He did so with vicious ferocity in some blood fueled rage.
After this vicious slaughter of his entire tribe he snapped out of this rage only to find himself among all their bodies, all he could think was to run and that's what he did, right out into the snowy tundra of the mountains and toward the base, perhaps he'd be able to find somewhere to hide from the thoughts. He had collapsed from exhaustion and hypothermia mere miles from civilization and upon awaking he'd find himself in a mortuary, the young man was as thin as a skeleton and his clothes barely fit.
It took him hours to get his bearings but once he had, he ventured into what seemed like a room where all the body's clothes were placed, probably to wash and give away to the poor. Cassie had found what seemed like a very nice black suit and upon exiting he'd begin his life anew as a mortician while he tried to think things over.
In the time he had settled into civilization and came to terms with his situation he had been contacted several times by Yog-Sothoth and even encountered his father once again as a handsome looking crow which was a godsend of sorts. His path took him on several trials which rewarded him with a new bird friend and knowledge that would help him start the cult.
He assisted people out of kindness during his journey who joined his cult which allowed him to build the cult relatively easily. every decade or so he seemed to recruit someone sufficient in being his apprentices. Those individuals being Sonatina, Soyoko, Moses, Miri, Carnation, And his brother Waya.
Waya had only discovered the massacre after the fact, he tracked down his brother while Cassie himself had thought he killed his brother, their meeting had been yet another godsend. Near the end of Cassie's trials, he'd be placed in a tomb and into a deep sleep to awake in the 21st century to be the cult's messiah.