Go Ask Alice. Anonymous.
While I was reading this book, the way this girl's (doesn't have a name, this was all in a diary, and wanted to keep any names out), life was going to lead to a horrible future. One incident was when her and another girl ran away to California. Of, course they came home and promised they would never do it again. But, that didn't last long, they ran away two other times. This girl also was messing around with drugs. At first, the drugs were not her fault, but then after it was. I knew this would all lead to huge, deadly unhappy ending. She was later placed in a mental hospital and a drug record that she would have carried around with her for the rest of her life. When, she got that first drink, the first time her and her friend ran away, I believe it all lead to her suicide. To her believing that life would not get better, in reality it was. She was getting her life back on track and then she was hallucinating. And, it took another innocent teens' life.
Yes, the foreshadowing was only for the reader and not for the character to know. She probably knew what she was doing, but really didn't care or was so addicted that she didn't really think about it.