Park's first impression of Eleanor isn't positive, but he still lets her sit with him on the bus. She's not like the other kids; this is possibly due partially to her abusive stepfather and difficult home life. Park thinks:
Today the girl was wearing a giant men’s shirt with seashells all over it. The collar must have been really big, like disco-big, because she’d cut it, and it was fraying. She had a man’s necktie wrapped around her ponytail like a big polyester ribbon. She looked ridiculous.
Later, though, they bond over a shared love of comic books and music. They grow closer and help each other navigate their difficult families. Park's family isn't abusive, but they don't completely understand him. Eleanor worries over their burgeoning friendship because it's one of the only good things in her life. Rainbow Rowell writes:
Every morning when Eleanor got on the bus, she worried that Park wouldn’t take off his headphones. That he would stop talking to her as suddenly as he’d started … And if that happened – if she got on the bus one day and he didn’t look up – she didn’t want him to see how devastated it would make her.
Eventually, though, they fall in love. Park is able to express it verbally but Eleanor isn't. Still, she has feelings for him. One night they grow closer and she agrees to go to prom with him. He says, "I . . . just really don’t want to say goodbye to you, Eleanor. Ever." But she goes home to see her things destroyed. Eleanor describes it:
No, liquid makeup. With little bits of broken glass. Eleanor carefully picked a shard out of the cat’s tail and set it aside, then wiped her wet fingers on his fur. A length of oily-brown cassette tape was wrapped around his leg. Eleanor pulled it free. She looked down the bed and blinked until her eyes adjusted to the dark . . .
Eleanor leaves and moves in with other family members. She isn't able to write to Park and he becomes depressed. He misses her. He thinks of her even when she isn't responding to the things he sends her. He thinks:
The final issue of Watchmen came out a few months after Eleanor left. He wondered if she’d read it, and whether she thought Ozymandias was a villain, and what she thought Dr Manhattan meant when he said, 'Nothing ever ends' at the end. Park still wondered what Eleanor thought about everything.
Ultimately, though, Eleanor reaches out and makes contact. It helps Park feel better about everything that's happened and allows him to feel hope for the first time since she left. Rowell writes:
He sat up. He smiled. Something heavy and winged took off from his chest.
Eleanor hadn’t written him a letter, it was a postcard.
Just three words long.