His father shows him that a king drives his kingdom, his court, his family with his appetites and his strong arm (and his backhand); his mother teaches him that he should have everything he wants, as anyone of Lannister blood deserves. His grandfather lectures him about moderation every once in while, but Joffrey has read his histories, and he hardly thinks Grandfather showed moderation when he slaughtered the Reynes and the Tarbecks like the dogs they were - he wonders if Grandfather liked it when they begged and screamed, the way Joffrey likes it when Sansa is obviously trying not to cry.

Joffrey knows what a king is - a man who holds a kingdom in his fist and squeezes it as he likes - and he is as good at being a king as he knows to be.