What is the relationship between Ilsa Hermann and Liesel Meminger in The Book Thief?Please Describe.

The relationship between Ilsa Hermann and Liesel Meminger
is one fraught with tension.  Liesel does seem to be a bit angry with Mrs. Hermann for
not continuing to have her laundry done by Rosa.  Liesel thinks that the mayor and his
wife must still be able to afford Rosa's services even though Ilsa says that they
cannot.  Liesel does not feel guilty in any way for stealing a book from Ilsa's library
and figures that the lady will not even notice that one book is missing from among so
many.  Once Ilsa notices that Liesel is stealing books from her, she does not scold the
girl and figures that she must be in some way starved if she resorts to breaking into
her library.  Ilsa feels that she can provide Liesel with what she needs, so she allows
her to come into the library.  But the two remain relatively guarded and thus the
relationship is tense.  Liesel never really trusts Ilsa, and Ilsa is unsure of Liesel's
motives.  Their relationship is symbolic of the ultimate tension of the time in which
they live--the circumstances of the war do not allow them to have a bond that they
otherwise might have.