Piggy is essential to Lord of the Flies and without him the novel would lack some of its realistic elements. Piggy is the brains behind Ralph, ever logical and supportive of Ralph. He lacks charisma; hence, he is only able to channel his inventiveness through Ralph.Refer to the enotes Study Guide and navigate to the Characters for a clear and concise breakdown of all the characters which will help you understand Piggy's role in the novel such as;
For all his intellectual powers, however, Piggy is basically ineffectual without Ralph. Piggy is a man of thought, not of action, and he is physically weak because of his asthma.
The fact that Piggy wears glasses creates that stereotype of the intellectual and his glasses themselves do become instrumental in the development of the novel from making fire to leaving Ralph and Piggy almost helpless against Jack's 'tribe' when they steal his remaining lens. Piggy's intellect is not enough on the island and cannot protect him.
Piggy remains the voice of reason throughout, even when Simon is killed and he is forced to contemplate his own part in Simon's death.
Piggy is killed and the conch destroyed basically simultaneously when Roger rolls a rock down the cliff. This is symbolic as Piggy, the most rational and mature of the group is killed by Roger's actions as Roger is released from the constraints and the
"taboo of the old life . . . the protection of parents and school and policemen and the law"
Ralph's reaction when Piggy is killed reveals
"the end of innocence, the darkness of man's heart," and
"the fall through the air of the true, wise friend called Piggy."