Tone and Mood

In the book Ender's game Ender has a tone that he is extremely intense.  He is always trying to do good stuff but he usually dose the bad thing for a good reason.  He always fells bad for hurting people.  He is so stressed out too.  One time he bit his own hand so hard that it started to bleed.  But the mood of the book is serous.  He dose not let people push him around at all.  In the first chapter he was getting bullied a little bit but then he was not going to take it anymore and he beat his bully to death.  All of his friends are kind of sacred him now because of his tone.