early in season one Rom teamed up with the Naguses son to kill the nagus and Quark. It was a flawed plan and did make him out to be an idiot when it all blew up in his face.
Rom grew up.
Rom got a new job, basically ending a slaves life, a little dignity. raised a son who in the beginning was embarrassed by him, bedded a super hottie and married her, and then became Grand Fucking Nagus where at he played Lincoln creating massive social reforms for women and fair play.
Kim on the other hand didn't change at all. No adventure he had had a lasting effect on him. Gods, season 7's Nightingale has us beleive that kim is releived that he's still a kid who doesn't have to worry about choices and responsibility.