Yeah lol it's not like these are aspects of Holden's character that are mysteries that are revealed later on. If you're not picking up on this stuff about him right away, in the first few chapters of a very short novel in an AP English class....maybe you DO need the teacher to point things out!

OP is also, like Holden, an unreliable narrator in this story because they are certainly paraphrasing their teacher - I'd be curious to see how the teacher would relay this part of their lesson.