Thanks! Zerlon is kinda-sorta a constitutional military dictatorship, if that is not a contradiction in terms. In other words, the holder can choose his or her favored successor, but the successor must be acceptable to the people. If the successor is rejected, generally the guards choose someone from amongst themselves whom the general population will accept. Tir succeeded her uncle as holder, but before that, she was in the guards and worked her way up on her own merit.

Binders are not part of the regular power structure in Zerlon, though that does not always hold true for other lands. So it's a coincidence that Riam is the binder while Tir is the holder, though ironically, that oddity makes them seem more normal to Morgalen!