The Seekers of Enlightenment was not an alliance given and asked for members like most. It was an alliance that was formed out of the group that was created around the phenomenon of the Angiens. Here is the history, from my point of view, as to how it was formed.
During the period when the Seekers of Enlightenment was formed, the Shades had appeared to Khalazdad, and both sides were readying armies to do battle. Wodin was training his troops and Khalazdad was recruiting soldiers for the recently-created Necrovion Sentinels. During this period of time there were lots of “bright” ideas, and people were running around, trying to discover things. One such initiative was a group of people centered on Angien’s Ferry. Some people believed that if the Shades were going to start a war, otherworldly beings would be helpful in opposing them. Since there was so little information available about the Angiens, they seemed like saviours.
This group at Angien’s Ferry slowly gained more people, and research began on a larger scale, with many people working on their own theories.