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.
Lord of Snow and Shadows by Sarah Ash. The Tears of Artamon trilogy.
http://www.sarah-ash.com/books/32/lord-of-snow-and-shadows/
Lowly court painter Gavril Nagarian learns that he is the rightful heir to the harsh arctic kingdom of Azhkendir, that he possesses formidable powers that compromise his humanity, and that he is being targeted by bitter rivals...
Gavril Andar who has a surprisingly vivid dream, and is subsequently kidnapped from his home in Smarna, where he resided with his mother, Elysia. He is taken to Azhkendir and informed that he is the son of the recently deceased Lord Volkh Nagarian and that he is to assume power as his father’s heir. Gavril soon comes to understand that his father’s Drakhaoul, Khezef, had sought him out and possessed him...
