Family is an important theme in the novel The Outsiders by S. E. Hinton. Ponyboy has his brothers to nurture him and look out for him. Johnny does not have a nurturing family to show him love. This is the reason that Dally is Johnny's hero. Johnny wants Dally's approval and love because he sees Dally as more than a friend. Dally is, in a sense, his family. Ponyboy does not need Dally to fulfill that need for him because he has his brothers. Dallas has survived on his own and this is appealing to Johnny. It helps Johnny relate to him.
Dally loves Johnny the most but I would not say Dally isn't Ponyboy's hero. The reason Ponyboy is alive at the end of the book is because Dally put out the fire on Pony's back and giving him the jacket in the beginning of the book or he would've been burned in a minutes of seconds.