trystane is the youngest of the martell kids, and hasn't really been brought into the business yet. i think that to a certain extent his father babies him and wants to keep him clean. someone to put on a good face for the family, and make good connections (ie. myrcella). however, he is a party boy and enjoys the family business (the purest, and best designer drugs). he will soon learn more about the business when things start hitting the fan (jon arryn dying, ned stark being made police chief or whateves). before, he stayed in the clubs, at the family's hotels, and on private jets enjoying life.