This is actually a shared pen name as we co-write our story. We're both juniors at The Ohio State University, and we've been working on this story since July 2006. It has evolved in more ways than you could imagine, and we only just recently boiled this story down to what we wanted it to be.
Our individual pennames are:
-Big Town Avenue: http://www.fanfiction.net/u/1270677/
-So Confusingly Amusing: http://www.fanfiction.net/u/1271479/
Our inspiration, other than The Outsiders itself, are songs and most importantly, their lyrics. All of our chapters will have song lyrics to accompany them; starting them out, signifying breaks in time and ending them. The lyrics have driven a lot of the stories we've written with these characters and we're never sick of finding new songs that fit into it. I guess we're just poetic like that. : )
Tender is the Night is our first story out of a few. As of now, we have three or four stories planned that follow these characters as they grow up. We'll post more information about that as we get a bit more organized on this front. We're still trying to figure it all out ourselves.
If you would like to add in your two cents about fanfiction, here's a great message board for practically anything relating to The Outsiders: 731 N. St. Louis St.
Happy reading!