He is so brilliant. He shines. He's beautiful with his hands that grab things and his tongue that says things and the way he stands and chews his food for so long, mashing it into a paste before he swallows. I will miss him and little Zoë, and I know they will miss me. (1.20)
Enzo's reflection on Denny is full of the purest, most selfless love that it basically makes us want to cry. We can hear how much he loves Denny just from the way he describes him, and he wants Denny to let him go so Denny can live his life.
"I love you," she said. "I love all of you, even your racing. And I know on some level that you are completely right about all of this. I just don't think I could ever do it myself." (8.38)
This is why Eve and Denny's relationship works. They love and understand each other without trying to change each other. And sometimes, when they don't understand each other, they accept that without trying to force an explanation from the other. #relationshipgoals
I had always wanted to love Eve as Denny loved her, but I never had because was afraid. (8.49)
Enzo's desire to protect Denny and keep him for himself made him both envious and afraid of Eve, but all it took was Enzo to show Eve a bit of love for her to love him back.
Denny did not stop loving Eve, he merely delegated his love-giving to me. I became the provider of love and comfort by proxy. (12.9)
Denny is sensitive of Eve's needs, and he knows that in some ways he is helpless when her illness takes her, so he asks Enzo to act as intermediary, because it's all he can do. It's back to that theme of control: understanding when you can and can't act, and doing what you can in the meantime.
"I don't care what you look like," [Denny] said. "I see you. I see who you really are."
"I care what I look like," she said, trying to muster her old Eve smile. "When I look at you, I see my reflection in your eyes. I don't want to be ugly in front of you." (23.82-83)
This is another moment where it's Denny's turn to respect Eve's wishes, even though he doesn't understand them. So he goes home, leaving Enzo and Zoë with Eve, because he loves her.
"You!" [Annika] wailed, and started crying. "You flirted with me all week. You teased me. You kissed me."
"I kissed you on the cheek," Denny said. "It's normal for relatives to kiss on the cheek. It's called affection, not love." (25.73-74)
It's clear that Annika and Denny have very different interpretations of what's going on here, but that's understandable, given their age difference and their different perspectives on love. Denny, who has a wife and a daughter and has experienced adult love, knows that he doesn't love Annika and probably didn't intentionally egg her on. Annika, who's fifteen and presumably hasn't been in a serious relationship before, is experiencing what she believes to be love for the first time. Sparks certainly aren't flying here.
"I made them love me too much," Zoë said softly, looking into her bowl of melted ice cream. "I should have been bad. I should have made them not want to keep me." (40.29)
Although Zoë doesn't understand the entirety of the situation, she does know that her grandparents and father are fighting over her, and she's able to pull from that, to some degree, that the situation is her fault, even though Denny has done his best to protect her from the reality of the situation. Poor kid.
They stayed with us for three days, and they hardly left the apartment. For the afternoon on one of those days, Denny retrieved Zoë, who was so pretty with her hair in ribbons and a nice dress, and who had obviously been coached by Denny, as she willingly sat for quite a long time on the couch and allowed Denny's mother to explore the terrain of her face with her hands. Tears ran down Denny's mother's cheeks during the entire encounter, raindrops spotting Zoë's flower-print dress. (53.2)
This is an intimate moment for the Swift family. Denny's parents, who haven't met Zoë before this, fall in love with her instantly—and unlike Eve's parents, they offer Denny anything they can to help him keep her. Because they're nice people.
"We never did right by you," his father said. "We never did right. This makes it right." (53.20)
Even though Denny's parents weren't present for a lot of his life, it's clear that they didn't stop caring about him and clearly regret their absence from his life. We're sure he appreciates the boon to his finances, but sending him a birthday card or something once a year wouldn't have hurt, either.
"I love you, boy." (58.56)
This is one of the last things that Denny says to Enzo during his last minutes on earth, before he lets Enzo know that it's okay for him to go, to be free from his life and his dog body and his pain. It's the simplest proclamation of love in the book, and the most bittersweet. No, we're not crying. You're crying. Now hand us that tissue box.