In the beginning Piggy talks about how he is physically weak since he has asthma but he was always supportive and loyal to Ralph and having a civilization since the start. He also shows how much he dislikes Jack.
then as the book goes on you start to see that he is the most mature one of everyone. Like how he actually cares about the little kids and how he's the one that tries to organize them. You can also see how he is loyal to the conch and rules.
Piggy also experienced Simon's death but was in denial and once he accepted it he said it was an accident and didn't agree with Jack's group savagery .So piggy was big supporter of civilization through out the whole book and died defending it.