
Valerie S. answered 06/14/19
Tutor of Many Trades
The protagonist is the main character of the story. As far as we can tell so far, there is nothing that sets Cammie's brother up to be the main character here. If he was the main character, he would most likely at least have a name by now.
The foil is the character that contrasts with the protagonist in a way that emphasizes or clarifies the traits or behavior of the protagonist. One way that Cammie's brother could have been written to be a foil is by describing him as someone who does not like social media and does not like to socialize much. But this character as he is written is not really a contrast.
The narrator is the voice that is telling the story. The narrator here is third person, not first person, and so the narrator is not any one of these characters.
The most fitting descriptor for Cammie's brother is the antagonist, because he is interfering with his sister's plans to meet Greg in person. The antagonist antagonizes (interferes) with whatever the protagonist is doing.