Stefan and his brother have been inseparable from birth. It's a phrase you hear often, particularly for twins, but in Stefan's case it's a little more literal than usual. While Stefan was born strong and healthy, his brother was not so lucky. Ill and sickly he was birthed, and expired within a few hours. Their mother followed soon after.
There the story would have ended were it not for Stefan's latent shamanic ability. Born a medium, his soul was a lightning rod for that of his brother's, and the two souls, so close in essence, fused together.
Still it was not a perfectly equal merging. Even a few hours in the world had anchored Stefan's soul more firmly to the material, and they soon settled into a benign coexistence, with his unnamed brother taking up residence mostly in Stefan's right hand. As Stefan grew so did the brother (who Stefan, thinking himself quite clever, named Dexter a few years into his schooling) in personality and power.
As their merged souls grew, however, they began to attract the attention of less savory creatures, drawn to the boys like a beacon. While at first benign or faintly mischievous, stronger and more malevolent spirits soon began to congregate, drawn now not just by the boys' souls but the gathered energy of a dozen small animal spirits and lesser poltergeists. Stefan and Dexter were amused by the spirits' antics (despite the punishments laid on them by father for "their" pranks) at first, but as time went on the darker manifestations began to frighten them. By the time the local wildlife started dying, being flayed and nailed to trees near their house, and Stefan's frantic pleas for father to save them from the evil spirits grew worrying, their father had had it.
He made arrangements to send them to the asylum (run by a small cult of Sarenrae devoted to her aspect as a healer), for the priests to sort out. He had no sooner set his seal to the letter and sent the messenger on his way that the malevolent spirits struck again, giving him the same treatment as the animals. When the priests from the asylum came to collect Stefan the next day he was drenched in blood and stone silent on his knees next to his father's corpse.
Ironically, the priests believed his story once they managed to coax it out of him months later. It was not uncommon in Ustengrav for the supernatural to run amok. Unfortunately the sight of their fathers' flayed corpse had well and truly broken the twins, both taking up residence at the asylum for many years. First as a patient, then as a student, as both wished to learn all they could about spirits and how to avert harm from them.
It was there they met one Professor Petros Lorrimor, a scholar of some renown. While initially coming to discuss with the priests as part of a treatise on the varied (and often bloody) schisms in the Sarenite church, he came to be interested in Stefan's unique haunting, as such a truly symbiotic relationship with a spirit was so rare as to be unheard of. The two formed a quick rapport, and while the relationship started as a mere scholar with his object of study, they soon began trading information tit for tat, Stefan getting a crash course in religion, the undead, and demonology.
While Lorrimor's mentorship lasted a scant month, it led to a well acclaimed treatise on Lorrimor's part (overshadowing, in some circles, that of his study of the Sarenite Schisms) and left a fondness between the both of them. While they conversed via letter on occasion, Stefan and Lorrimor never met face to face again.
Years pass, and Stefan stands on the cusp of taking his vows as a priest of the Redeemer. Before he is fully ordained, he receives his scheduled leter from the Professor...though it comes with terrible news. It appears this will be the last letter he receives from the late Petros Lorrimor.
A detour is not out of the question before he binds himself to the priesthood, he supposes, and the priests agree.
