The Keepers are divided into three orders which function as largely separate entities. Keepers from different orders may work together, but usually don’t.
The Order of the Star
The Order of the Star is the largest of the orders. Their responsibility is the policing of magical society, which mainly comes down to enforcing the peace of the Concord.
Members of the Order of the Star deal almost exclusively with mages and adepts, making them the most visible of the orders to other mages. The Order of the Star’s area of responsibility brings them into contact with non-Light mages on a regular basis, and as a result members of the Order of the Star are the only group among the Council who have significant experience interacting with Dark mages.
Out of all the orders, the Keepers of the Order of the Star probably get the messiest and the most unpleasant cases. Mages really, really don’t like being investigated, which means members of this order have the unenviable job of being required to piss off their fellow mages on a regular basis. They have to investigate both Light and Dark mages, and it’s arguable which is worse. Dark mages don’t recognise the authority of the Keepers and if they feel threatened are quite likely to shoot on sight. On the other hand, Light mages who don’t want to be investigated will use their connections to bring pressure to bear on the Keepers, which may lead to the investigating Keeper being reprimanded or punished.
Keepers from the Order of the Star are given nearly all the political investigations, meaning that Keepers of this order have the dubious distinction of being the order that gets most frequently and deeply involved with Council politics. Keepers who show political talent can rise far and fast in the Order of the Star, but a misstep can make them fall equally quickly.
The Order of the Cloak
The Order of the Cloak is responsible for monitoring the relationship between magical and mundane society. Their two primary duties are to maintain the secrecy of magic, and to restrict magical interference in mundane politics.
Given that there are over fifty million normals in England alone, the mages of the Order of the Cloak are massively and perpetually understaffed. They deal with this by making heavy use of subordinates, delegating as much work as possible to adepts, sensitives, and sometimes even normals. As a result the Order of the Cloak contains an unusually high proportion of adepts and sensitives, and non-mages have more opportunity for promotion here than they would in any of the other Keeper orders, or indeed most of magical society.
Members of this order spend a lot of time dealing with normals, and so tend to find brute strength less valuable then the ability to operate undetected. As a result the Order of the Cloak contains a high fraction of living magic users and other more subtle types.
The Order of the Shield
The Order of the Shield is the smallest order and also the most militant. Their responsibility used to be the protection of humans from magical creatures, but with the steady decline of magical creatures in Britain their focus has shifted from anti-creature to general combat. Nowadays they function as the Council’s military reserve: when something blows up, it’s members of the Order of the Shield who are called in to deal with it. Given the nature of modern magical society, this means that members of the Order of the Shield spend a lot more time in conflict with mages than with nonhumans.
Active members of the Order of the Shield are assigned cases which either have already turned hostile or are expected to get that way, such as arrests of Dark mages or search-and-destroy missions against magical creatures deemed dangerous. Members of this order are sometimes also called in by the Order of the Cloak or the Order of the Star if a case gets violent, though the other orders are reluctant to do this unless absolutely necessary.
Most members of the Order of the Shield are not kept on active duty. Instead they are kept in reserve, rotating through shorter cycles where they’re on call and longer ones where they are nominally on leave. In emergencies off-duty members of the Order of the Shield can be called in, and in the past there have been periods where this happened frequently, but nowadays it’s extremely rare.