The episode stands out in having an entire community as supporting antagonists, in the form of a town called Dudley - whose residents seem to have extremely prolonged life-spans but are starting to fall victim to a rare disease.
The disease is spread due to consumption of contaminated chicken, which have been fed the ground up remains of deceased humans - victims of a gruesome cannibalistic cult that kept the town young at the price of some of the resident's sanity.
Arens would be the executioner of the cult and betrayed the original ideals of the community alongside Harold and aided in killing and cannibalising members of their own community (having traditionally only hunted "outsiders).
Arens wore a tribal mask when committing his terrible deeds and had a large axe that could easily decapitate victims, whose bodies were dumped in the river.
Ultimately Arens was shot dead by Mulder when he attempted to behead Scully as part of a crazed ritual orchestrated by Harold, it is uncertain what became of the rest of the town of Dudley but many were presumably charged with various degrees of conspiracy, cannibalism and murder.