Father Angelo

He's tasked with training Luciano in the ways of being an exorcist, much like he was taught during his childhood by Father Giovanni. His relationship with Luciano is more like an older brother is to his little brother, rather than pseudo father-son. Because he's lived with the church for most of his life, he's seen its inner workings and is secretly against organized religion in general. He's passing down that view to the next generation via tutoring Luciano.