Great Husband is the informal title granted to men who marry the women who become the velikomats of the Matriarchate of Periaslavl. Feodora Borisovna? was the first to choose a Great Husband, and her heirs continued and expanded the tradition. By the eighteenth century, it is expected for the velikomat to have three Great Husbands.
They serve Periaslavl in a variety of roles, including generals, diplomats, merchants, administrators, or whatever else is needed. They also provide assistance whenever their velikomat needs for her magic.
From the Books: "The emotions of the Great Husbands were their primary gift to the Velikomat, not their wisdom, prowess, or skills, great as those might be. They may not have known when she asked them to marry her exactly what they were promising, but they had made the promise. Now, ruthlessly, as she had done many times before, Irina stripped them of all emotion, stripped them of almost all that made them sane and human, adding all of their great hearts to her already large mass of focused emotion." IAAWT, p. 23