On the shores of Lake Nemi there was a temple of Diana unique from other divine sanctuaries, in that the priest role was typically held by an escaped slave.
The legend goes, a runaway Slave of Rome might escape his master by serving as a priest of Diana, the Goddess of the Hunt, in her Lake Nemi temple. But to earn the office of priest, he must first kill his predecessor in single combat. And to keep it, he must remain ever vigilant of the next slave looking for freedom.
An ABCs of Gods, Myths, and Superstitions.