The dragon king had left home early to go for a walk. He was too tired and had a lot in his mind to think about. Having the boy he loves rejects him right before his face didn't help the matter.
Avan didn't bother to explain what happened to him; he just ignored him like giving him an explanation for his actions wasn't necessary. He left, not interested in forcing Avan to talk to him.
He had enough problems as it was, and adding more stress to his plate wasn't an option. Money, that was the main thing that worried him. They were too many to be leeching off someone else when they had their own family to think about.
He had no idea why people valued paper with other people's faces and used it for purchase. Giving paper a cool name doesn't change the fact that it is still paper at the end of the day. Gold and silver, he understood, but the paper was new and worrisome.