The Sun Also Rises First Two Characters.. Will they cover my leftovers?

Okay, so a foil is defined as a character who acts as contrast to another character.
I know I shouldn't admit this, but the only characters that I know of so far (besides the many women of Cohn) are Jake and Robert. Hemingway characterizes Jacob through his own thoughts and Robert through Jacob's narration and dialogue. They are best friends, but completley opposite of each other. Because Jacob views everything so practically, his personality turns cynical. And then there is Cohn, who is in the process of some fantasy reality check: "Do you know that in about thirty-five years more we'll be dead?"..."Well, I want to go to South America" (page 19). Robert's parents left him a large sum of money, so he really doesn't have to work for much, whereas Jake is busy working so he will be able to eventually enjoy life. I love how split their personalities are and how they interact with each other. I'm going to take a wild guess here, but I think that maybe Cohn is the protagonist and Jacob is the foil who constantly tries to bring Cohn back to reality, but in the end, is actually sucked into Cohn's world and learns a thing or two from it.

My favorite Jacob quote (so far): "I have a rotten habit of picturing the bedroom scenes of my friends" (page 21). Jake's personality shines through this quote. He is so cynical about life- living it versus experiencing it. on the contrary, Robert is dying to experience life-he knows that so far he hasn't done anything with his life, but maybe he takes it too far.