Drone minds - like those of most humans - tend to decay into something resembling senility unless specific and comprehensive remediation steps are taken - basically, wholesale editing of deep memory and a full-scale reset of their personality. Why this should be the case is, perhaps, not entirely understood; it appears to be an inevitable property of mind, of the kind of sentience the Culture prizes so much. Not everybody welcomes such disruptive and invasive mental excision, of course; many humans simply prefer to die - comfortably, after a long and full life, and surrounded by friends and relatives, no doubt - rather than submit to such extensive intellectual updates.
For drones, perhaps, it is not senility, exactly, from which they suffer; but they do tend to develop certain sardonic personality traits, snarky characteristics, and often a vague and wandering turn of speech - all of which may be the result of far too much exposure to both the vagaries of the human condition and the fundamental randomness of the Universe.
As it is for humans, a quiet death after a long and useful life is certainly an option for drones. But, even in decrepitude, there is still knowledge and wisdom to be discovered - or rediscovered - in the minds of the old, if it can be distinguished from the repetitive dross that senility seems to bring. This is one purpose of Group Minds: to retain that knowledge and insight for future generations, while allowing the individual intellects to decay comfortably and naturally into glorious senescence.
The Master of the Dojo is not, and never has been, a human, or even anything even vaguely biological. He is a remnant, the projection chosen as the public face by an old drone, one who was once called Loash Armasco-Iap Wu-Handrahen Xato Koum, and is now a small fraction of the Group Mind called Phrontisterion.
There are many other remnants who preserve enough of their old personality and individuality to maintain a projection capable of conversation and at least the appearance of independent thought. For some reason, though, those forming Phrontisterion choose to present themselves as human, regardless of their original form. So, when I visit with my requests and supplications, I find myself dumped into a different place depending on who I was trying to reach: a university common room for the Professor, a Dojo for the Master, or an old-fashioned Library stuffed with leather-bound books and rolled manuscripts for the Librarian.
Every few days, somebody - often an actual drone or human, a virtual mind-state abstract representing some distant Mind, even the occasional physical Avatar - comes to me to solicit an introduction to one of the facets of Phrontisterion. It is my task to make the requests, politely, even humbly, on the visitor's behalf. More often than not, the application for a visit is accepted by the remnants - although I have to make it clear that elements of Phrontisterion will sometimes choose to decline an interview without feeling obliged to give a reason for their decision.
My next scheduled caller, I already knew, was anticipating a visit to the Professor - an ex-Contact drone remnant once known as Quenlily Sikralis. Unusually, the visitor was an Avatar: a humanoid representative of a ship Mind, of the ship on which I was a passenger: the GSV Inevitably Successful In All Circumstances. Such an unusual occurrence had piqued my curiosity; I was looking forward to finding out exactly what was going on.
But first I needed to facilitate the Master's interview with Formali-Kai. The tiny drone bobbed in the air in front of my face, now displaying flecks of rosy happiness against its formal blue. I blinked again, to allow the drone access to the Dojo, in the virtual world inside my head.