I just finished reading the reason I jump by Naoki higashida. It was really great. It's about a 13-year-old boy with autism that answers a series of questions about his autism it's pretty fascinating :-) I think you may enjoy it
I read it last year. When my son says something random over and over again, I remember the boy from this book saying that a particular phrase makes him happy, and I don't wonder why my son says it.