Ponyboy is surprised that he and Cherry get along well because he has stereotyped Socs based on what he and his friends and family have experienced. Ponyboy has not known any Socs to be kind or considerate, or even sensitive; he has not recognized the fact that Socs have problems, since he has only seen them as privileged in every sense. Ponyboy has seen the cruelty that some of the Socs have shown people like Johnny Cade. When Ponyboy and Cherry begin to get to know one another, he finds that she reveals a side of herself and possibly other Socs, that he had not considered:
..."I'll bet you think the Socs have it made. The rich kids, the West-side Socs. I'll tell you something, Ponyboy, and it may come as a surprise. We have troubles you've never even heard of. You want to known something?" She looked me straight in the eye. "Things are rough all over."
It is important to remember that the main conflict in this novel is based upon Socs vs. Greasers. Because Cherry is a lot like the queen of the soc girls, it surprises Ponyboy that he and she can carry out an entire conversation and see eye-to-eye with one another about so many life issues, especially since he is a Greaser. They seem to have a great deal in common, despite their socioeconomic differences and the fact that they live on "different sides of the track." As Ponyboy points out a few times in the novel, he and she both see the same sunset, despite being on opposite ends of town.
I agree with what these two have said, and, I'd like to point you out one thing; "You know not all Socs are like that" said Cherry.
"Yeah, right..." Pony laughed.
"I'm serious! That's like saying all you Greasers are like Dallas Winston."
Ponyboy was surprised that he was friends with Cherry because she was part of the Socs', the rich kids who had everything. How could she possibly have anything in common with Pony when he was from the other side of the tracks. He was a Greaser and she was a Soc, total opposites. Pony thought of the Socs' as spoiled rich kidss with no consideration for people's feelings or any else that should have mattered. Ponyboy is so sensitive and caring, that he doesn't believe a Soc would understand him. He groups Cherry as just another Soc that would usually be cruel to him and treat him badly, just because of his background and social status. The Socs' looked down upon the Greasers. They thought they were better, just because they had more money. Socs' didn't associate with the Greasers because to them, Greasers were poor and pathetic, low class compared to them. So Pony figured, Cherry would be that same way, materialistic, unfeeling and shallow. That was not the case, however, and Pony soon found out that he and Cherry had a lot in common. She wasn't like the other Socs'. Cherry Valance was warm, intelligent, caring and thoughtful, to his surprise. The two became friends, regardless of their obvious differences.