If he were to do that and if that were the key to dragon riding here's how I think he might go about it without completely showing his cards before time. He might begin in the first book with a character and emphasise his fierceness and fire for life. Like undefeated Khal Drogo. Then he'd associate colouring between the character and dragon he becomes. Black for his braid probably. And probably do some name association, like add a letter to the character's name to make the dragon's, like Dr