My honest opinion about this series: not so good.
The story has potential, but the writing is just... I dunno.... not good. There is a lot of telling how people are, but not showing us by their actions. Scarlet is supposed to be a temperamental guy, but hardly ever acts it. We also are told at least 3 or 4 times in as many pages that his race, the Hilurin, has black hair, pale skin and black eyes. Things like that.
The first 50 pages of the first book introduce all these lands and races of people and then does nothing with them, they never appear again. The whole second half of the series is set in the far north, which isn't on the map. So we have a map of many lands and places, which we don't need, but the map we do need we don't have.
Poor Scarlet is pretty much locked in a ship's cabin and then a royal apartment for two books straight, because else he wouldn't be safe from rape/murder apparently, but that gets quite boring for the reader. He supposedly has all these special powers, but doesn't do much more than light the occasional fire without a flint. He pretty much sits around waiting for his significant other to come home and visit.
The end is totally weird. After moping around (when not having pretty graphic m/m sex) for a book and half wondering about court intrigues and how to win respect from the arrogant icepeople, Scarlet gets a Divine revelation in the last 20 pages that his God is really a space ship, that his race and the icepeople were originally on board of this ship. Yadda yadda, there is this mighty weapon the Hilurin have hidden somewhere the icepeople can't find it. He tells his lover Liall and they agree they shouldn't tell anybody else. Done. End of that storyline.....
We quickly dispatch of a few heirs for the throne and then Liall gets
interrupted while chatting to Scarlet about all their traveling plans (finally, Scarlet is going to get out of the house!) because all the barons have declared him king. So, even though he's been swearing up and down he doesn't want to be king for the entire last book, Liall immediately accepts (without any consulting with Scarlet) and tells the crowd gathered in his bedroom: I will be king, and this boy of the despised Hilurin race who has magic you're afraid of will be my consort and if you don't like it I will kill you'. Or something. End of book. And apparently end of series. What??
I feel bad for Scarlet who a) still doesn't know his lover is about 80 years older than him and is going to outlive him by a few centuries or so and b) now gets to lounge around in the royal apartments watching Liall be king for the rest of his life.
All in all, potentially good story, but poorly executed. If reading a good fantasy/scifi is like falling in love, this one is more of a one night stand you vaguely regret in the morning.