War and Politics
The cadets participate in competitive war simulations in zero gravity, where Ender's innovations overwhelm his opponents. The war consists in a team deathmatch where they have guns that freeze your body or extremities. The goal is to get one person on the other team's gate without getting him frozen. Graff promotes Ender to a new army (named Salamander) composed of raw recruits, but Ender's success continues. He forms bonds of friendship, loyalty and trust with several of his current and former squad members, like Petra. A jealous commander of another army, Bonzo Madrid, compels him to fight at the bathroom, and Ender quickly overpowered him. In an act of self-defense, Ender kills Bonzo.
On Earth, Peter Wiggin uses a global communication system to post political essays under the pseudonym "Locke", hoping to establish himself as a respected orator and thence as a powerful politician. Valentine, despite not trusting Peter, publishes alongside him as "Demosthenes". Their essays are soon taken seriously by the government. Though Graff knows their true identities, he recommends that it be kept a secret, because their writings are politically useful.
"He even thought of Valentine then and wanted to go home." (Scott Card 102)
As I assumed before, Valentine has an influence on Ender and makes him want to leave Battle School and return home. I think this might be foreshadowing and Ender might actually return home, leaving the war away from him.
"'Just between you and me,' Petra said, 'if they gave the Battle School an enema, they'd stick it in a green green brown.'" (Scott Card 109)
Again, as I predicted, Ender's relationships can and do affect him. Here, we can see Petra console Ender and try to cheer him up. I can make an assumption that his friends might keep him at Battle School and, if he makes it, later in battles against the buggers,
Conclusion
Like I predicted, Ender's relationships with others affect how he behaves and probably how he will behave in the future. Ender isn't a person who makes friends easily, but so far he has a good group of friends to be there for him. I believe that Petra might be a love interest for Ender, but Ender hasn't shown any love emotions yet and he's only 8.