He and Marty hadn't talked much since the funeral. Marty stayed busy as a chemistry major at Seattle University, which was good, it seemed to keep him out of trouble. But college also seemed to keep him out of Henry's life, which had been acceptable while Ethel was alive, but now it made the hole in Henry's life that much larger. (2.4)
It's hard for Marty to accept that his family has gotten smaller—and more distant—since his wife's death. Now that Ethel is gone, who's going to keep him and Marty connected?
"I'm not like Yay Yay—not like your grandfather," Henry said, as he realized where this was going, stunned to be categorized in the same breath as his own father. He loved his father, deep down, what son doesn't? But after all Henry had gone through, all he'd seen and done, had he changed that little? Was he so much like his own father? (18.40)
Henry still loves his father, but that doesn't mean that he wants to be like him—or have the same kind of relationship with his own son. He wants to be accepting of Marty's decisions no matter what, because that's what true love entails.
Ethel's last year had been a rough time. When she'd been lucid enough to engage the both of them, he and Marty had seemed to get along famously. But once her health declined, and the word hospice came up, the real disagreements had begun. (18.3)
There are still hard feelings between Henry and Marty over Ethel's death last year and how her treatment was carried out. Henry believes he did the right thing in keeping Ethel at home, but Marty thinks they should have given her the best hospice care money could buy.
Henry could see Samantha out of the corner of his eye as he tended to the tree; it was like she was checking off an imaginary list. "You're a great cook, you like to garden, and you're the best fisherman he's ever known. He told me about all the times you took him out on Lake Washington for sockeye." (19.25)
Henry's had a strained relationship with his son, so he's surprised when he learns that Marty has told Samantha so many good things about him. It's clear that Marty does love and cherish his father—he just has a hard time showing it. The apple, as they say, doesn't fall far from the tree.
His father pointed at the door. "If you walk out that door—if you walk out that door now, you are no longer part of this family. You are no longer Chinese. You are not part of us anymore. Not a part of me." (35.49)
Wow, that's harsh. When Henry's father finds out that he's been hanging out with Keiko, he doesn't waste any time giving his son an ultimatum and threatening to disown him. Way harsh, Pops.
Henry would sit occasionally and have one-way conversations with his father. It was all he could do. His father wouldn't even look at him, but Henry was certain the man couldn't turn his ears away. He had to listen; he was too weak to move on his own power. So Henry spoke gently, and his father, as always, stared out the window, pretending not to care. (35.14)
Henry's father may not want a relationship with his son anymore, but that doesn't mean that Henry will give up on him. He'll still talk to his father so that they share some memories with each other.
But somehow Henry's mother, sorting the mail first, found the letter each week and slipped it underneath his pillow. She never said a word, but Henry knew it was her doing. She did her best to be an obedient wife, to honor her husband's wishes, but to look out for her son as well. (37.4)
Even though Henry's mother listens to her husband, she's not going to abandon her son completely. She'll still take care of him and make sure that he's okay, letting him know through her actions that she'll always be his mother.
Still, his fingers gripped Henry's so slightly it was almost imperceptible. And a single phrase slipped out. "Saang jan."
It meant "stranger." As in "You are a stranger to me." (38.35-36)
A near death experience doesn't change things for Henry's father—he refuses to make amends with his son and work on their relationship. Instead he calls Henry a stranger, making it clear once more that he doesn't want anything to do with his only son.
Henry looked at her parents sleeping. They seemed more restful here, in this cold, wet place, than his own parents in their warm, cozy home. (41.10)
When Henry sees Keiko's family, he realizes what he wants for himself: a warm, loving family that supports and cares for one another no matter what. Even in the worst circumstances, the Okabe family still manages to find contentment because they're all together.
"I'm sending you back to find what's missing. Sending you back to find what you let go. I'm proud of you, Pops, and I'm grateful for everything, especially the way you cared for Mom. You've done everything for me, and now it's my turn to do something for you." (50.31)
Now that Marty is an adult, he better understands the sacrifices that his father made for him—and how difficult his life was. He wants to be a good son and do something selfless for his father for a change.