Hearth Keeper's Guild
The Hearth Keeper's Guild — the Choema Gwyld — is the closest thing in the Known World to an institution for the protection of slaves, and it is not one. It is an association of owners holding each other to a standard, which is a narrower thing than an advocacy body and more effective than it sounds. Membership signals something; expulsion signals much more. Slaver houses prefer to sell to members, so the sanction has money and reputation behind it.
When a member fails with a slave, other members tell him so to his face. Part of what they work out is whether he mistreated her or was Saenydd about her from the start — whether he failed at correcting her or at matching her. Where they find abuse, what follows depends on the city: a magistrate in Shining Reach, expulsion elsewhere, after which he buys from nobody reputable again. Where a member cannot pay to treat a sick slave, the guild sometimes pays out of its dues, because it would rather pay than watch a member fail where the city can see. It counts a willingness to free a slave who is ill-fitted among the marks of a member worth having. And whatever its charter says about standards, a large part of what it is for is men who have found the weight of carrying another person's decisions heavier than they expected, talking to other men who have stood where they stand.
None of it reaches a man who never joined.
The guild has chapters in every city and is the institution of the moderate reformers — those who accept the Natural Order and do not accept that community alone prevents harm.