If my memory serves me right, he is the head of a rather insignificant border duchy; compared to Frida, whose father's lineage includes royal blood, he is practically a pauper.
The main line of the Deer family died out around the time between the Bitter Ash War and the Second Eclipse: out of the 4 children of Duke Connell Deer, three did not have any descendants, and the only daughter, Kate, who lived to adulthood, became the wife of Duke Vyacheslav Gryphon. Later, Kate's lineage would become the basis for her direct descendant, Ivan Gryphon, to claim the imperial crown, and at that time, the Deer's possessions were inherited by the younger, collateral branch of the family, descended from one of Connell's cousins.
Duncan is from the Duchy of Deer. Although Duncan traces his lineage to an ancient family connected to the glorious Falcon dynasty...