"You Are The King Of Ys"

I think that it is appropriate that Gratillonius continues to be styled "King of Ys" for his lifetime. He won the Kingship by the appointed means, in combat, and has not lost it in combat unless with the Gods Themselves. He is still regarded as King by the survivors and, most importantly, he retains his leadership role. This is even more crucial when the Ysans must survive the loss of their city. They build another city immediately, not generations later like Romulus following Aeneas.

It is impossible that Gratillonius have a successor as King of Ys. Not only were Ysans Kings not succeeded by their sons. Because of the peculiar relationship between the Gods, the Queens and the King, they did not even have sons. The Queens had daughters who could become Queens and each King was either killed by the next King or appointed by the Council of Suffetes when a King died other than by combat in the Wood. All of these institutions for appointing a King no longer exist.

Does Gratillonius have a son with Verania? Probably. I do not remember but will continue to reread. But, in any case, it is Verania's younger brother, son of a senator, who becomes a King of Armorica.