The only way he knew how to deal with the anger and not lose control was with his punching bag in the basement.
-- Narrator (Chapter 1)

Importance: Luke worries about expressing his anger out of fear of becoming like his father. He feels that he needs to keep it inside. The only way he feels that it is acceptable to express is by punching his punching bag.

Luke hated the present tense, like she was going to walk in the room any minute now and scoop him up in her arms.
-- Narrator (Chapter 4)

Importance: Clayton uses the present tense to talk about his mother. He is only three years old and is unable to understand that Natalie is gone forever. Luke is upset by this as he had to deal with the fact that he will never see his wife again.

He looked at me like a real person who happened to have cancer.
-- Natalie (Chapter 7 )

Importance: Natalie says this...