Three hundred years ago some human children began to be born as vampires. These have enhanced hearing, sight, agility, stamina and reflexes. In this universe vampires are considered a more perfect version of humans; i.e. closer to God. They have taken over the Catholic Church (the only variant of religion seen in this film, possibly the only one existing), and are called Brothers. They wear unadorned long black coats, and look very monseignor-ish. The Brothers state that they exist only to serve humans; to protect and guide them. Brothers live much longer than humans; the oldest are 300 years old and none have died yet. Vampires are removed from their mothers at birth, indoctrinated into the Brotherhood, and raised to believe they are superior to humans.
Human churchgoers donate blood for the Brothers to drink (one character states his mother gives blood three times a month at church, and in one scene we also see an elegant woman at a swanky party donating blood into a large collecting vessel with a tap at the bottom, from which Brothers are served in elaborate chased goblets). Brothers never drink blood straight from the human body.
Churchgoers wear rosaries; however not all humans are churchgoers. At some more infrequent church ceremonies humans also drink the Brothers' blood, and this gives them visions (some may experience prescience). The liturgy of the church states that mingling the blood of the two races makes one titular Perfect Creature.
Prodnose: Shurely shome mishtake? Ed.
Myslef: Oops, sorry. I keep on thinking it's Thursday.