What are some quotes in the The Outsiders that relate to the topic of gangs/friends as surrogate family?

I can  point you to a few quotes to get you started -

In Chapter 1.  Ponyboy tells us about the members of the Greasers:

"...the four boys Darry and Soda and I have grown up with and consider family.  We're almost as close as brothers, when you grow up in a tight-knot neighborhood like ours you get to know each other real well".

"...organized gangs are rarities - there are just small bunches of friends who stick together",

"If it hadn't been for the gang, Johnny would never have known what love and affection are".

Later in the book, in Chapter 7, Ponyboy says,

"We always just stick our heads into each other's houses and holler 'Hey' and walk in.  Our front door is always unlocked in case one of the boys is hacked off at his parents and needs a place to lay over and cool off.  We never could tell who we'd find stretched out on the sofa in the morning...(we'd) risk a robbery...if it meant keeping one of the boys from blowing up and robbing a gas station or something.  So the door was never locked".