The Brethren were a group of corrupted monks in Scotland. They could be recognized by their bald heads and orange robes.
Sometime in 1540s, the Brethren discovered the werewolf's crashed spaceship and decided to try to help it. They turned away from God and started to worship the Wolf. They provided hosts and food for the growing Werewolf for over 300 years. In 1879, they also arranged events in order for Queen Victoria to be bitten to start The Empire of the Wolf.
The Brethren used an unknown type of martial arts for offensive purposes, though they weren't above using guns for long distances. They might also have trained the Werewolf to fear mistletoe, but this is uncertain. (DW: Tooth and Claw)