discuss the various ways family is defined by the relationships depicted in this text

The Book Thief defines family in a number of ways, and Zusak has thoroughly displayed the many ways in which people outside of the immediate family unit can enter within its parameters and experience the same love they would have known had they been there all along.

Liesel becomes as a daughter to Rosa and Hans and sister to Max (although we'll always wonder what happened after the war).

Max becomes like a son to Rosa, I'd have to say the closest of friends to Hans.

The family's relationship changes over the course of the novel; they engage, disengage, engage, and then finally have to completely let go. When Max leaves, he doesn't do it for himself; he does it because he loves and wants to protect the people who have become HIS family.

Rosa begins as a caretaker for Liesel, she's distant, unlike Hans who immediately falls in love with his new daughter. But eventually, we understand that she wanted to keep her emotions distant in order to protect herself from further hurt. She becomes a mother to Liesel regardless of her attempts to hold back.