I recently read The Willful Princess and the Piebald Prince. We can note that Lostler and Burrich are both powerfully Witted. (Lostler’s son charger is powerfully Witted, Burrich brought a stone dragon to its knees with his Wit) Burrich also mentioned that the receive he detested the Wit because his grandfather saved his horse over his grandmother. Lostler was first encountered as a Chalcedean slave.
Are there any other hints or evidence against this being a possibility?