The conversation that starts Chapter 13 is not about Ender but rather about Peter and Valentine. Two American I.F. officers are discussing the other two Wiggin children, since they have finally tracked down the true identity of Demosthenes and Locke. The officers decide to follow Graff's advice on the matter, which was to do nothing, to let them continue, since they have not caused harm and may be correct.
Valentine, meanwhile, enjoys being Demosthenes, although Peter is as dangerous as ever, and they learn that the world is preparing for war. To a large degree Valentine has become her pseudonym. Graff picks her up after school one day and takes her to go see Ender. She is forced to trust him when he mentions that he knows who Demosthenes is; Valentine does not want Locke to find out about this meeting.
Valentine meets her brother again. Ender has been on earth for two months and has no intentions of returning to space. He does not want to fight, and he is sick of games. They talk for a long time, and Valentine learns why Ender is tired of fighting. He learns his enemies so well that he almost loves them, and then he destroys them. Ender does not want to destroy. He also knows that he cannot win all the battles. Valentine thinks he means that he will never be able to beat Peter, but she does not understand that he only wants Peter to love him. Valentine appeals to Ender, for her sake, to go save mankind. She leaves hating Graff for having forced her to convince her brother to return to where he does not want to go.
Graff explains to Ender that he was here to remember what he was fighting for, and he knows that Ender will hate him for using Valentine and the earth to make him return, but insists that his feelings for his sister are what really matter. Ender thinks briefly that Graff may actually care for him but decides that everything is calculation with Graff. On the voyage to Eros, where I.F. command is, Graff tells Ender all he knows about the buggers. Ender learns that they communicate instantaneously, and that from them humans learned how to do the same. They have the ansible, a device that allows ships to talk to each other from across the galaxy. Graff also tells him that all human ships have been sent out to attack the buggers in the Third Invasion, and he is expected to be the commander five years from now. Finally, Ender asks why they are fighting the buggers, and although Graff does not know, he speculates that a species that can communicate through thought must have a hard time understanding that humans are intelligent life at all. So it could all just be a misunderstanding, but when the species is at stake, there is no choice but to attack.
The various people in Ender's life cause him to come to terms with his identity in this section. Graff manipulates Ender's process of self-discovery, but Ender's sister Valentine plays a larger role. Ender still loves Valentine, and so she is able to influence him. She convinces Ender that he must return to space to save mankind from the buggers. Her appeal is on a personal level, and it works. Ender knows that he can defeat his enemies, and he can do that by understanding them better than anyone, but unlike Peter, when he understands them he starts to love them. It is then painful for him to destroy them. While Peter crushes what stands in his way without a second thought, Ender does not feel the same way. Ender is unconcerned with ambition or power, and unlike Valentine, would be content to live a normal life. However, he loves his sister, and, along with her, the rest of humanity. Because of this conflict, Ender has no choice but to go to I.F. command and prepare to fight the buggers. He is aware that he risks destroying himself, for he will again be forced to give in to his destructive side—Ender must act like Peter once more. It will be painful and the risks are great, but there is nothing that Ender would not do for Valentine. In the end it is his love that makes him strong enough to go on, and that forever separates him from Peter, who would not do anything for love. Ender hates himself because he is like Peter, and now his sister, the one person he truly loves, is asking him to go back to being like Peter in order to save her life. It is a tremendous personal sacrifice for Ender to leave earth, but for Valentine he will even destroy himself.
Once he decides to leave, Ender begins to pick Graff's brain for all that he knows about the buggers. Ender learns that by studying the buggers, humans have learned how to master communication at faster than light speed—the buggers actually think that way. He also learns the sad truth that the bugger wars may be due entirely to a misunderstanding. Assuming that the buggers communicate instantaneously with each other, how could they understand that humans are actually intelligent life forms? This possibility troubles Ender, but he is forced to agree with Graff that since they cannot know for sure that the buggers will not attack again, they must wipe their enemy out.