"When I jumped on top of him, my knees on his chest, he couldn't ask for anything better." (19)

This quote is significant because it shows how Phineas wants the narrator to be less of a robot and more free spirited like he is. I think this will play a big role in the story where the narrator both change the other person's personality in a way.

How are Phineas and the narrator friends if it seems they both have rather different personalities?

Phineas- outgoing, free-spirited, exciting, fearless, athlectic
Narrator- obedient, friendly, nostalgic, hesitant, friendly

Narrator- "' We'd better hurry or we'll be late for dinner," I said, breaking into what Finny called my 'West Point stride.'"
Phineas- "No Upper Middler... had ever tried. Naturally Finny was going to be the first to try... to inveigle others, us, into trying it with him."