Why did Johnny need the gang? How does johnny take care of Ponyboy after he kills Bob in the park? Why is this important?

Johnny Cade is the second-youngest in the greaser gang, besides Ponyboy. He is "smaller than the rest, with a slight build. He had big black eyes in a dark tanned face; his hair was jet-black and heavily greased and combed to the side, but it was so long that it fell in shaggy bangs across his forehead. He had a nervous, suspicious look in his eyes... He was the gang's pet, everyone's kid brother." Johnny saves Ponyboy from drowning by killing Bob. Johnny helps revive Pony after the attack and takes him to find Dally.