Welcome to Dean's series long debacle with identity issues!
Gosh what else can I really say about this one? Heck I should probably say something more about it here... lol.
Sam still keeps in touch with his college friends, who know nothing about his life outside of the guy they knew in school. All that's about to change, as they learn far more than they ever could've bargained for. He might manage to save his friends, but Dean loses his identity in the process.