What reason does ender give for not wanting to join the fleet.what reason does ender give for joining the fleet?

Ender is initially hesitant to join the fleet because he fears it will lead to him becoming like his older brother, Peter, who is manipulative and ruthless. He worries that joining the military will strip away his humanity and turn him into a tool for war. However, he ultimately decides to join the fleet because he recognizes the necessity of defending humanity against the alien threat and believes he can make a difference in the fight. This internal conflict reflects his desire to protect others while grappling with the implications of power and violence.