Tear Jerker / The Catcher in the Rye

• Virtually every interaction Holden has with Phoebe. She's concerned about her brother because he keeps hurting himself and she's genuinely concerned for his well-being. When she receives his note, she drops everything because she's so scared of losing her brother and it's ultimately what drives Holden to get his shit together. Mind you, she's only ten and Holden leaving wouldn't be the first time she's lost a brother.
• Holden talking about his younger brother, then abruptly stating that he died of leukemia. He then says, "You would have liked him".
• Holden's recollection about James Castle, a boy in his school who committed suicide by jumping out of a window because of bullying (or possibly something even worse) - while wearing a sweater he borrowed from Holden.

  Holden: I heard everybody running through the corridor and down the stairs, so I put on my bathrobe and I ran downstairs too, and there was old James Castle laying right on the stone steps and all. He was dead, and his teeth, and blood, were all over the place and nobody would even go near him. He had on this turtleneck sweater I'd lent him.