Lois Lowry 
Summer to Die 

Having a sister who is blonde and pretty and popular can be tricky if you’re like Meg – serious, hardworking, and, well, plain.But when Molly becomes seriously ill, Meg, no longer jealous, has to face up to something quite different: that Molly is not going to come home from the hospital, that Molly is going to die. Difficult to accept at the best of times, and when Meg has to cope with all the problems of growing up too, it’s the hardest thing she’s ever had to do.