It is correct up until the time of the end of the book "Arthas: Rise of the Lich King". In the book Arthas (as the Lich King) initially must deal with the spirit of Ner'zhul for lack of a better word haunting his helmet. He has an identity crisis throughout the majority of the latter half of the book where Ner'zhul is trying to turn him completely to the dark, and the spirit of the paladin Arthas (represented by a boy) is trying to pull him back to the light. They have a...