The apple of somebody’s eye
Definition 1 of 1
Pro Tip 1/3Emotional Value
Conveys strong affection, suggesting a deep emotional bond and often used in family context. 
My grandfather says I'm the apple of his eye, especially now that he's gotten older.
Pro Tip 2/3Endearing Terms
Often used among close relations to convey fondness without romantic implications. 
In her grandfather's stories, she was always the apple of his eye.
Pro Tip 3/3Not Literal
It's a metaphorical expression; don't use it to describe an actual apple or someone's eye. 
People chuckle when I say my cat is the apple of my eye, but it's true!