When I opened one of Blume’s books — “Blubber,” “Deenie,” “Forever . . . ” — I felt confident that she understood the pact: Blume had gotten there first, and she would tell us absolutely everything. Blume wrote about playground bullying and unnerving body changes and teenage sex and she wrote about parents’ failings. If her characters differed from my friends and me, it was that they could utter out loud their thoughts about subjects that were, to us, indescribably uncomfortable. Her books did not resolve with tidy, happy endings, at least not the kind I had come to expect, so that I read them with the same mixture of overheated expectation and anxiety that I felt about adolescence itself.