Paul Holden is the Soc who accepts Darry's challenge to square off first during the rumble in S. E. Hinton's The Outsiders. Paul was the star halfback on the local high school football team and
... he and Darry used to buddy it around all the time.
Now the two were opponents on another field of battle: Darry siding with the greasers and Paul, now a junior in college, representing the Socs. They both said their hellos, but hate now gleamed in Darry's eyes. Pony couldn't quite determine the look that Paul displayed.
Contempt? Pity? Hate? All three? Why?
As Pony explained earlier, little separated Darry from the Socs. He was intelligent, wore his hair short, had a job, and didn't hang with the greasers except when a fight was eminent. Darry supported his brothers, who were proud of being greasers, but Darry was
... ashamed to be on our side, ashamed to be seen with the Brumly boys, Shepard's gang, maybe even us.
Had Paul and Darry met up with each other after such a long absence under different circumstances, they may have greeted each other in a way that most old friends would. But now they were greaser and Soc, separated by territorial and social boundaries that forced them to slug it out with the other thugs that surrounded them.