I read the first book of trilogy back in 2007. The boy used to stay with his mother in a village and on his 16th or 18th birthday, he found out that his father was a king. The same night, he was kidnapped and when he opened his eyes he was on a ship. It was very cold everywhere.
The boy was actually a dragon and his father (i.e the king) had another wife who was pregnant and wanted her child to be the heir of the throne.
I can't recall anything more than this.