In John Boyne's The Boy in the Striped Pajamas, the main character is Bruno. Grete, his sister, is slightly older. As is the case with many brothers and sisters, the two youngsters don't always get alone. Bruno finds Grete very difficult to tolerate and he is also afraid of her.
Bruno sheds some light on their relationship and his feelings toward her:
'What is it?' he asked. 'Am I being sent away?'
'No, not just you,' [Mother] said...'We all are. Your father and I, Gretel and you...'
Bruno thought about this and frowned. He wasn't particularly bothered if Gretel was being sent away because she was a Hopeless Case and caused nothing but trouble for him.
When Bruno speaks of his sister, the reader realizes that he is not the only person that has difficulty with her.
...it would have made a lot more sense if they had left Gretel behind in Berlin to look after the house because she was nothing but trouble. In fact he had heard her described on any number of occasions as being Trouble From Day One.
We learn that Bruno's sister is three years older than the nine-year old Bruno. Bruno finds her difficult to deal with first because she likes to think that she is the boss—in charge of him.
...[Gretel] made it clear to him from as far back as he could remember that...she was in charge. Bruno didn't like to admit that he was a little scared of her, but if he was honest...he would have admitted that he was.
Bruno also catalogs his sister's "nasty habits," which include staying in the bathroom much too long, especially when he has to "go." Bruno is sure his sister's dolls stare at him, and some of her friends are not very nice particularly one who he calls "monster." They make fun of Bruno because he is short, which he especially hates. Chapter Three is also named for Gretel, entitled, "The Hopeless Case."
In Chapter Three we also learn that Gretel agrees with Bruno's unhappiness in leaving their old home. The statement reveals that the brother and sister disagree much more than they agree:
Gretel looked at her little brother and found herself agreeing with him for once.
Gretel drives Bruno crazy, and she seems to cause some difficulty for their parents as well, but their mother (Bruno notes) is careful to treat both children with love, as does their father.