Van and his family had believed that Folken had died during the rite; their mother, Varie, went to search for Folken, and did not return. When Balgus went to search for them both, he found no trace of them.
This effectively orphaned Van, with only Balgus and Merle as his trusted teacher and friend. Having been alone most of his life (and shunned by others who knew of his Draconian heritage), it was with shock that he discovers that Folken had been alive all this time, and had abandoned him.
Worse, when he discovers it was Folken who was behind the attack on their homeland, he feels betrayed and struggles to believe his brother's actions.
For his part, Folken seems not to understand Van's feelings, and wants him to put them aside, so they may be together again as family.