As I was reading Shadow of the Hegemon, I noticed the unique "language" that the children use to communicate. By language, I mean mostly, the use of slang, (Terms like "greeyaz" and "kuso" come to mind), but it is more than the individual words. Somehow, it feels like a separate language of the 'insiders' -- battle school grads. Like real groups of friends do, they speak more than the sum of the words, there is additional meaning, between friends, that the reader can feel a part of.
How do you create this language so that it comes across to the reader as more than English with a few random slang-terms, and allow the reader to feel like a part of the group, albeit a silent one? In addition, how did you come up with the actual words?
I raided Arabic, Japanese, Vietnamese, Russian, and other dictionaries -- particularly dictionaries of slang terms. Then I made the changes in those terms -- of meaning, spelling, and pronunciation -- that would be inevitable in their becoming part of the slang of the battle school as a whole. By no means did I go as far as such a slang would surely go, because I had to maintain intelligibility for the contemporary reader.