Jack Kerouac seems to have been preoccupied with the question of duality from a very young age. He seemed to feel that there was more than one person inside him. Indeed he would veer from friendly, open and so on to someone who was angry. In a way, there was a swing also between his American self and what he later called his Franco-American older brother. There was a swing between the deeply introverted part of himself and the person he became out in the world, having to act in an extroverted way.