Perhaps. . .
The Elves are split into three or four main houses.
Dalos would be of a different caste than the rebels; causing sparks between them at the begining. Something would happen to set them off from the main group, like an ally they didn't like or a method they hated.
After being set off from the group, they find the source of the energy; a Twilight Well, a spring containing water from the Twilight Mountain.