There are hundreds of shorter and/or picture books to add to this list, & they are available, but since others are offering their favorites, I wanted to put some older books I've found valuable & add the ideas from other readers, which are in blue.
Empathy
My Left Foot - Christy Brown
The Water Is Wide - Pat Conroy
Call Me Maria - Judith Ortiz Cofer
Freak The Mighty - Rodman Philbrick
The Acorn People - Ron Jones
Mockingbird - Kathryn Erskine
Seedfolks - Paul Fleischman
Because of Mr. Terrupt - Rob Buyea
Wonder - R.J. Palacio
Crash - Jerry Spinelli
Bud, Not Buddy - Christopher Paul Curtis
Peer Pressure
The Wave - Todd Strasser
House of Stairs - William Sleator
Wonder - R.J. Palacio
Humor
The Princess Bride - William Goldman
Kneeknock Rise - Natalie Babbitt
Life Goals
Tuck Everlasting and - Natalie Babbitt
The Green Book - Jill Paton Walsh
The Wish Giver - Bill Brittain
Writing
Love That Dog and Hate That Cat - Sharon Creech
The Search for Delicious - Natalie Babbitt
A Child's Garden of Verses - Robert Louis Stevenson (2)
Death/Saying Goodbye
Kindred Souls - Patricia Maclachlan
The One And Only Ivan - Katherine Applegate