Compare Grey Wolves (Henderson's Boys) by Robert Muchamore with the Boy in the Striped Pajamas and The Book Thief. How are all three of these books similiar?

If you don't know what Henderson's Boys is, please feel free to look it up, or just tell me that you cannot understand the question. Also, if you don't know what Henderson's Boys is, just compare The Boy in the Striped Pajamas and The Book Thief together. Thank you!

Zakary C.