Piggy is one of the four main characters in William Golding's Lord of the Flies, and in almost every way he is an outcast from the rest of the boys on the island because of how he looks (fat, asthmatic, bespectacled) but also because of the way he thinks. Piggy is naive because he assumes everyone thinks as he does.
When he meets Ralph in the opening paragraphs of the novel, he assumes Ralph is as glad to see him as he is to see Ralph; however, it is not true. In fact, Ralph tries several times to avoid talking to Piggy and to distance himself from the unappealing boy. Piggy wants to talk about the plane and the crash and the rest of the boys; Ralph mostly wants to revel in the fact that there are no adults on the island. When Piggy asks Ralph's name, he assumes Ralph will do the proper thing (as Piggy himself just did) and reciprocate. Instead,
the fat boy waited to be asked his name in turn but this proffer of acquaintance was not made; the fair boy called Ralph smiled vaguely, stood up, and began to make his way once more toward the lagoon.
Ralph is just not interested in anything to do with Piggy or his ideas. Any time Piggy offers a bit of information, Ralph quickly interrupts and shuts him down.
When the boys all finally have a meeting, Piggy asks and tries to remember each boy's name; he assumes Ralph will want to know them, too, but he is wrong. Ralph is dismissive and does not care in the least about knowing any of the boys' names.
Later, Piggy tries to help Ralph be a better leader by making practical suggestions and reminding Ralph that he is the leader, and Ralph eventually becomes desperate enough to listen to him. In the meantime, Piggy assumes that holding the conch shell will allow him to speak freely and uninterrupted, according to the rules to which they had all agreed; however, when Piggy tries to speak he is taunted mercilessly and shouted down by the majority of the group. He assumes Ralph will stick up for him since it is the right thing to do, but Ralph is silent.
Perhaps Piggy's greatest flaw is his naivete, his belief that everyone thinks logically like he does and is interested in maintaining a civilized, orderly society. This is so far from what the others, particularly Jack, think that eventually Piggy is killed because of it.