Note: Much of this information is inferred, and there is still speculation and discussion concerning some aspects. None of the information on this page should be taken as canon, and it will evolve as new information comes in.
Binders are in essence a messenger and information gathering organization with a network of informants/initiates spread across Europe and Asia. Their members consist entirely of women, and the society itself is known to few others. They do not kill or assassinate, and as far as we know they have no specific association with any major religion. They appear to identify with Minerva, and believe in a 'greater spirit' (Chapter 13), known as the Bind-Mother, but details are still sketchy about these beliefs. The Binders are antagonistic to the Mongol Empire, and have given aid to Christendom in the form of intelligence and guides, but they are not affiliated with the Church in any real way.
The Binders have a sophisticated information network. The members contact each other with secret languages, using carrier pigeons and Binder couriers to convey their messages. Within cities, members form chapters similar to those of the Freemasons.
Members appear to be adept at covert and intelligence gathering skills like stealth and multi-lingual knowledge. They undergo systematic training before being fully initiated. Binders close to each other have the facility to communicate and stay in contact with each other in a sort of telepathic manner.
Girls can become Binders either by being born from a Binder mother (orba matrae), or they can be chosen. Upon entrance to the Binders, new members take a number of vows, among them an oath not to kill.
Mobile couriers have a system of leaving messages for each other not dissimilar to the hobo code in America. Knotted rope and arrangements of mundane items seem innocuous to everyone else, but leave important information to any passing Binder. They share a silent language (sign language?) known as Rankos Kalba, or Rankalba, which uses a combination of taps and grips on the other person's arm to convey a message, similar to the manner in which they leave messages in the wild. It is rare for anyone outside of the organization to know it, particularly males.
Binders bear no grudges... Binders bear nothing but messages and knowledge. - the orphan's tale - Chapter 24A, The Mongoliad
From this, we know the sisterhood adheres to a strictly pacifist ideology. Although, this does not mean they remain completely neutral. We don't know why they side with the people they do; with Frederick against the Papacy, with Christendom against the Mongols, but they certainly pick groups to help and groups to hinder. Probably their allegiance hinges on multiple socio-economic and political factors; but these reasons remain clouded as yet.
Many Binders cultivate a distant, neutral, even emotionless demeanour (Chapter 13). This is partly a conscious decision; they try to remain apart and look at things objectively. But it is also part of their nature as Binders. They take no vows of celibacy (most Binders are Binders because their mothers were Binders), but they often lead a solitary life, as the society calls for its members to be highly secretive, loyal, and mobile. This is common among secret societies, but complicated for Binders as their uni-gender setup requires their members to connect with outsiders in order to propagate. Although, it is worth mentioning that while we have seen a fair number of mothers, we haven't seen any fathers. It is possible that Binder liaisons are fleeting and transient by design. It may be no Binder may marry, though she is free to have sexual relations as she chooses.
Fan fiction character Ranjisek Soon, mother of Dysingli Soon, appears to be a Binder. Also Osseran, the wife of Dershod appears to display some of the Binder characteristics. Since she is the mother of two twin daughters, it will be interesting to see if both or one of the offspring will also become Binders.
