The Book of Skaith, book 1.
Stark learns that his foster father Ashton vanished on the planet Skaith. Despite Ashton's official position, nothing can be done. But Stark can do much on his own.
He arrives at the planet, is told to remain in the city, the one place starships are allowed, fishes for information and is contacted for a way out. It is a very conflicted land. The sun is ginger because it is dying (on an unscientifically accelerated time frame, BTW), and trouble is ensuing. Plus the last time the Migrations occurred because of how cold the planet grows, the Lord Protectors established a rule to protect and provide for the weak; alas, over time, most people have gotten themselves into the "weak" group. Some want to escape the planet. Others want to prosper through trade -- including slave trade.
And a wise woman made a prophecy about a dark man who would come in search of Ashton and overthrow the Lord Protectors. She was murdered, but her daughter Gerrith inherited her role. . . .
It includes genetically modified, now non-human races; using the bones of a human sacrifice to divine with; a bridge exploited for extortion; a rescue that is not an improvement; the mobs of Farers and the more efficient mercenaries; Stark's Mercury childhood among non-humans; and more.