Bruno Tavoularis is a former convict and current Flatliner who follows Uriah Bishop and works for the Missionary Works of the Holy Ghost. He currently runs the Church of the Angelic Host as a pigment cult through Skinriding the church's reverend.
It is never specifically said why Tavoularis was at Marion Federal Penitentiary, but it was obviously heinous enough that he was sentenced to death row for it. He found religion while there, before Project Flatline found him. When he escaped, he followed Bishop for reasons known only to himself, but possibly attracted to Bishop's own charismatic expressions of faith.
Tavoularis' job is three-fold. First, he controls the Reverend Cale O'Reilly, head of the Church of the Angelic Host, by using the arts of Skinriding. This includes using Contaminate to make it appear as though O'Reilly has been cured of a horrific case of pancreatic cancer; in truth, Tavoularis has only suppressed the symptoms, and the cancer continues to ravage O'Reilly's body. This may prove to be a downfall for Tavorlaris unless he can figure out a way around it.
The second job Tavoularis has is to lace the church's communion wine with pigment. The parishioners are not aware of this practice and believe their visions of angels (in truth, ghosts) and their renewed faith (in truth, pigment addiction) are due to O'Reilly's miracle granted through Christ. The third job is for Tavoularis to choose suitable candidates, such as sensitives, and send them to Bishop and the Missionary Works.
Tavoularis has been having disturbing visions as of late that have been shared by many of the congregation; an old woman who serves as God. These visions have shaken Tavoularis for some reason, and have made him question his once rock-steady faith.