I read Rules by Cynthia Lord.
If someone says “Hello”, say “Hello” back. Say “Thank you” when someone gives you a gift (even if you don’t like it). Don’t stand in front of the television when other people are watching it. No toys in the fish tank. Rules, rules, so many things David doesn’t understand! It’s hard enough for any twelve-year-old to make her way in adolescent society…but so much harder when you have an autistic little brother! Catherine loves David deeply, and protects him all she can, but his embarrassing behaviors present a real challenge in her search for the ideal best friend. One day, as Catherine sits sketching in the waiting room during one of David’s many doctor visits, she meets someone who really throws her for a loop and changes her whole perspective on who she is and what kind of relationships matter most. What was it that turned her world upside down, and what is “normal” anyway?