Ponyboy's conflict with the Socs has changed his overall character development. Over the course of the story, he changed his thinking of the Socs. He went from thinking of them as just an enemy to thinking of them as people who also have rough times and watch sunsets. For most of the story the Socs only hurt Ponyboy and his friends, but during middle and end of the story when he speaks with Randy and Cherry, he realizes that things are truly rough all over.
Ponyboy living on the East Side critically affects the development of Ponyboy's character. I think the author chose the poor side of the neighborhood because it has more action and leaves a lot of room for the character to grow. With this, it is obvious why the East Side affects Ponyboy so much. The part of town he lives in shows him the bad part of the world but also opens him up to thinking how things are rough all over. The shabbiness of his home just strengthens his character.
Darry influences Ponyboy substantially throughout the story. When Darry slapped him, Ponyboy strengthened his belief that Dally just didn't like him. But soon after when Ponyboy returns to his brother at the hospital, Ponyboy realized that his brother was just caring for him all along. This change of thought with Darry began to show up with other things in the rest of the book, like what Ponyboy thought of Dally to what he thought of him later. This change of thought is just Ponyboy growing as a character.