Like any good foil, Henry is pretty useless on his own. We just use him to learn about Dean. Sal meets Henry just after he leaves (abandons?) Dean in New York. Although he is similar to Dean in the sense that he's gone to jail, Sal tells us that Henry doesn’t have Dean’s saintliness. Henry makes it clear to us how special Dean is. Dean’s not just a wise guy who spent some time in jail and knows how to con. Instead, Dean has admirable qualities (saintliness, holiness, purity) that allow Sal to put him on a pedestal.