Dendra

The Dendra are a strange cult of cannibals that take on the thoughts and memories of those they consume. While their numbers are small, they have dedicated cloisters all across the united states wasteland. Rumor has it that they started overseas, but not much is known about their past.
They refer to their deity as the 'Promised End', although they do not worship her. According to the Dendra, this being consumes the life of everything that dies; she is a personification of decay and oblivion, and she grows with every soul that passes into the beyond. The Dendra seek to stop this Promised End, and to do this they consume bodies, allowing the essence of who that person was to flow into them as they slurp up their bone marrow. In doing this, they prevent that person's soul from being claimed by the Promised End and allow their memories to live on through the world.
Despite this objectively grim mode of operation, the Dendra are rarely rabble-rousers and more often take the role of sages or wisemen. In the areas of the wasteland where their strange ways are tolerated, they serve communities through consuming the recently deceased. In places where they are excommunicated from nearby societies, their ways can often become deadly, tribal, and shamanistic. Whenever one of their number dies, it is, of course, consumed by their brethren.
After a long life, a Dendra can become full of other people's personalities and memories, often appearing as incoherent to the common people. It is only when their mind is too muddled by memories of other lives to even eat more bodies that a Dendra is finally considered 'Full'. Full Dendra are consulted as seers and considered the wisest amongst their peers, despite usually needing someone to translate their gibberish. Doing so is an art, but if you can get a straight answer out of them, there knowledgeability is actually stunning.
Leaders of the Dendra are called the Disidia. They are selected by the former Disidia before their passing and everyone watches the new Disidia consume the old one's body as a ceremony of their new leadership. In order to be considered for the position of Disidia, the candidate cannot have consumed another body. The old Disidia's body will be their first, and last, cannibal meal. This is to ensure that the leadership of a Dendra cloister never truly changes. The essence of each Disidia is added to the consciousness of the new one, creating an ever-growing entity that remembers all the way back to when the Dendra were founded.