So, I'm interested, and I have an idea for a dark side cult, if you'll let me know if this will fit in. 

The Family. Hierarchy is superficially quite simple, with only two tiers. Sibling, and Child. 

Siblings, titled predictably as "Brother [name]" or "Sister [name]," are nominally equal. None is permitted to hold dominion over the others, but don't be fooled into thinking this makes them a democracy. Each does as they please, with the single rule being that they may not harm each other. Despite constant internal strife, they are (generally) unreasonably loyal to one another, and will band together without a thought against any outside threat. The number of siblings is limited by the Family's collection of lightsabers. You must have one to gain the title, but no one in the Family actually knows how to build them. 

Children are a combination of apprentice and slave. They are taught the traditions and skills of the Family, and often pitted against each other to sharpen those skills. In a bizarre twist, while Siblings are forbidden to harm their Brothers and Sisters, Children are encouraged to try to kill their elders to claim one of the Family's prized lightsabers. This is both the Children's only means of advancement, and the Siblings' primary weapon against each other. You may not harm your Brother, but you can train his successor, and orchestrate his death. 

Their philosophy is fairly typical, if quite unsophisticated dark side rhetoric. They use strong emotions to bend the Force to their will, with a particular reverence for pain as a source of power. It is quite common for their garb to include deliberately painful eleme to, such as spikes, needles or even piercings that affix to the garment. As the Force has quieted, they have resorted to stranger and more drastic versions of this practice.