The colour beneath the uniform

As my prior post may have shown, I have been playing a bit of Skyrim over the last week... constantly.

Now, spoilers ahead, I will hereby explain and analyze my favourite part of the game: The Dark Brotherhood.
Whoever wrote this delightful, quirky and adorable group of insane, evil murderers has mastered something that I myself try to include whenever uniformed, secret societies show up. Something I call "The colour beneath the uniform".

To me, there are two kinds of interesting secret societies.
The first is the "Sorrowful Men" category. (For those who don't know, "The Sorrowful Men" are a guild of assassins in the "Song of Ice and Fire" series and (to me) the best thing that came out of those books. (Personally, I don't like them, Game of Thrones or anything that came out of that writer's feather. I can see that it is not "bad" but I just can't get into the setting)
Now, the Sorrowful Men are interesting, because of one thing: When they kill you, they whisper "I am so sorry!" into your ear, before doing the deed.
I love that!
That implies so much about them. How there are things going on that go beyond every single member of the group. How they know that, in order for the world to work, they have to do horrible things and suffer for it.

And then there is the other kind.
This brings us back to the Dark Brotherhood of Skyrim and to my personal approach to secret societies and cults.
I view it like this: In order to join a secret society and plot or give yourself to the uniform, you need to be deranged, desperate or in some way driven.
Cult members look like common people and may even act like normal people, but they are, at least in some way, crazy.
And those people make for incredibly interesting stories. Sometimes much more interesting than their cause.
You may have seen that whenever I introduce a new Follower of the New Moon in Between Day and Night, I attempt to make them not just as plausible as possible, I also try to make them interesting and unique.

Another wonderful example for this would be the cult in the book of a man, whose ashes I worship ever day, Terry Pratchett.
One moment!
Somebody just told me that Pratchett was still alive.
Then whose ashes is that over there?
Anyways, I am talking about "Guards! Guards!" and the dragon cult in there. A delightful group of weirdos.

Where I am going with this is simple: If you use a secret society or cult as part of your story, make either their cause so interesting, that their faces don't matter or make their face so intersting that the reader will want to read about them, no matter if they wear their uniform or not.