Well, I mean, in a lot of ways.
I think she showed Ponyboys personality by events that happened to Ponyboy. Like when he and Johnny were at the park and the Socs came up and started beating them, and when Johnny killed one of the Socs, Ponyboy kept his cool and came up with the idea of running away, he didn't freak out or anything.
The author shows how responsible and level-headed Ponyboy is by the experiences he goes through