One of the books I enjoyed most growing up was Zazoo by Richard Mosher. I recently reread it and was relieved to find it's a great read for adults as well.
The main character is a girl adopted by an older man. With her Vietnamese looks, Zazoo doesn't quite fit in at the little French village. She's mature for her age, which leads to her taking on a lot of responsibilities, but also helps her gain some special friendships.
It's inevitable to get very attached to all characters. I love how they all have multiple dimensions that get revealed over time. Sometimes that comes as a horrible surprise, but overall sweet things tend to happen.
Mostly it's about the past, and how it still affects the present, even if we're unaware of it.
Within this story there are many stories to discover and unravel. Many stories that will probably stick with you.