Variety is the Spice of Style...
S.E. Hinton has a well-stocked writer's toolbox. She knows that mixing things up will help keep us from getting bored. We'll give you a brief tour of some of the elements she uses.
We can see that the story is told in the past tense... but so are lots of stories. Yet, sometimes the use of that tense is more significant than others. Here it's definitely important and is part of the overall form Pony has chosen. He's writing his memories of the tragic events that he was recently a part of.
Pony already knows how the story will end when he's writing it, and he uses this knowledge to build suspense by providing little hints along of the way of what's to come. Here's one of many examples:
I really couldn't see what the Socs had to sweat about – good grades, good cars, good girls, madras and Mustangs and Corvairs – Man, I thought, if I had worries like that I'd consider myself lucky. […]
I was wrong. (2.126)
This foreshadows Pony's later realizations that the boys in the rival gang have struggles that are similar to his own, just with a twist because of their distinctly different social, personal, and economic environments.
Use this word to impress your family, friends, and teachers. An "epistle" is simply a letter—as in the kind you write to your pen pal. An epistolary novel, then, includes letters, diary entries, or other documents reproduced in the text. Some novels are made entirely of such material.
Ponyboy includes the text of two letters in the story: the letter Soda writes him when he's in hiding and the letter that Johnny hid in Gone With the Wind. We discuss that second letter—the slightly disturbing one—in Johnny's "Character Analysis," but here's a snippet:
Listen, I don't mind dying now. It's worth it. It's worth saving
their kids. Their lives are worth more than mine, they have more to live
for. Some of their parents came by to thank me and I know it was worth
Soda's letter is much more lighthearted and funny. What we love is that it includes the misspellings. Which make it seem more realistic. Soda writes "mising" instead of "missing," and "yourselfves" instead of "yourselves" (5.92).
We are just full of fancy words today: "vernacular" language is the informal speech used by the people in a particular group or area, rather than a "standard" language used for more formal speaking and writing.
Ponyboy writes his story with all of the slang that he and his friends use. This makes the novel spicy, and gives us a window onto the way people in another place and time talk. And, if you have a similar speech pattern (probably if you've a time traveler from the mid-20th Century), it gives you something to relate to. Here's a meaty example:
He meant rumbler. Those Brumly boys have weird vocabularies. I doubt if half of them can read a newspaper or spell much more than their names, and it comes out in their speech. I mean, you take a guy that calls a rumble "bop action" and you can tell he isn't real educated. (9.62)
This is a kind of a hilarious moment, because it shows Pony judging another gang of Greasers the way people often judge him and his gang. Vocabulary and speech patterns are a result of complex factors, and you can't necessarily judge a person's education level by the way they talk.
So, nope—Pony isn't being fair here. Although some of those boys probably don't have as much education as Pony, some of them might have more. He doesn't know them, and he doesn't get to know them in the book.
Bonus: if the topic of regional and social speech patterns interests you, explore "Do You Speak American?" on PBS.