The Saints of the Source

With the The Empty Ocean and the rivers that flow to it playing such a crucial part in the ecosystem of Ananke - much of it beyond the knowledge or understanding of the people that live there - it makes sense that a portion of the population attach a sort of religious reverence to the water. Over time, this special interest grew to fanatical worship, and the cult known as the Saints of the Source came to be. They can be found all over Ananke, but one important location to them is the whirlpools of the Empty Ocean, which is part of a rite of passage when joining the cult. The 'end of the flow' is seen as a lesson, the wastage of the rivers gifts due to irreverence.
The members of this faction became almost single-minded in their devotion to the water, shunning the civilised life in favour of roaming the rivers of Ananke on hybrid boat vessels, raiding and hunting and seeking ever more of the Erodite mineral. So how did they come to this belief?
The rivers on Ananke are huge and powerful. Awe-inspiring size and power are enough on their own to cause worship in a primitive people, not to mention the fact that water is essential for life and can be harnessed for energy, crafting, growing of food, and a number of other survival needs. However, the biggest factor in their infatuation with the rivers is Erodite. The abundant traces of Erodite in the water systems of Ananke cause widespread physical changes to much of the continents inhabitants, flora and fauna. Prolonged consumption, particularly in more concentrated amounts such as those found at the headwaters of the rivers, causes mutations in the consumer, and has contributed heavily to the wild array of creatures and plants found here. The River Reverence see Erodite, and the changes it brings, as blessings from the River, and seek always to consume more. The more mutated and influenced one is by the Erodite, the more holy they are, the closer to ascension they become. In essence, they worship the water because it brings them Erodite.
Their commitment to this belief alters their view of all other life on Ananke. They see the civilised folk as unworthy of the river's gifts, and hate them for consuming what Erodite they get from their water. This causes them to raid often, particularly in areas closer to the rivers, and sabotage systems designed to bring water to towns further inland. Most beasts and flora they hold no grudge for, as they believe these have true appreciation of the water. However, in rare instances a specimen will become so mutated by the mineral that the cult deem it to have "ascended to its pure form" by the blessing of the water. For these, the cult members seek out tribute - usually in the form of unwilling captives - to offer up as sacrifice and praise.
In a story and gameplay sense, the cult itself fills the role of the general world bad guys, the "bandit" types that each Borderlands world has. The mutation from the Erodite allows me to create more and more dangerous versions as players progress through the story, and the "ascended" creatures will serve as some fun, tough mini-bosses.
Note: Names of mineral and cult are very much working titles.