Peter Riley is the protagonist Hearts in Atlantis. The story follows Pete's addiction to the game of hearts and his struggle to maintain his grades and scholarship. As the story progresses, Pete starts dating a hippie named Carol Gerber. Carol influences Pete and he starts to join the counterculture, bringing his friends with him. The defining parts of Pete's character are his interest in Carol Gerber, his struggle with hearts, his political ideas, and his desire to stay in college.
Early in the story, Pete becomes addicted to the card game hearts. This occurs when Pete is trying to study, and his classmate Ronnie Malenfant ropes him into the game. Throughout the story Pete tries to kick the addiction to this game, despite Carol's warnings. For example, when Pete and Carol are working on the dishline, Carol brings up the topic of the continuous card games
"'How are your grades?' she asked. 'I know it's none of my business, but I want-'
'Information, yeah, I know. I'm doing okay. Besides, I'm getting out of the game'"- (393)
Later in the book, just before they leave school for Thanksgiving, Pete's roomate Nate warns Pete that he is in danger of flunking.
"'You're going to flunk out,' he repeated. Dull, bricky color was rising in his cheeks. "You and Skip are the best guys I know, there wasn't anybody in high school like you guys, not in my high schol at least, and you're going to flunk out and it's so stupid'" (439).
Despite these warnings, Pete continues to play cards. He and his best friend Skip Kirk make several attempts to get out of the game, but they are always sucked back in. However, after the Thanksgiving Break, and just before Christmas, there is an incident where everyone is playing cards. A boy notices Stokely Jones III, a cripple, hobbling through a driving freezing rain storm. Everyone stops playing to help Jones, but Pete and Skip are able to finally kick their addiction.
Another one of the principle aspects of Pete's character is his interest in Carol Gerber. In High School, Pete dated Annamarie. However, he started dating Carol, and didn't want Annamarie. Carol wants Pete to break up with Annamarie before they have sex. Pete finds himself unable to do this admist his struggle to maintain his grades and his continuation of hearts. Pete and Carol finally do have sex, just before the break. When Pete returns home, he calls Annamarie over to his house, and he breaks up with her. Just before she leaves she calls him a "Fucking Jerk" and slams the door loud enough to shatter the glass. When Pete returns to school, Carol is gone. He is heartbroken as after they had sex, she told Pete that she was dropping out to join the anti-war movement full time. Pete is crushed to find that she did not end up returning to school. Pete waits for her to write like she promised, and she finally does, after Pete kicks his addiction to hearts. She gives Pete a Christmas present, a copy of William Golding's Lord of the Flies, which was Bobby Garfield's favorite book. This brings up a continuing theme throughout the book of character's becoming at peace with themselves after receiving mail or meeting Carol in person. In "Low Men in Yellow Coats", Bobby Garfield is depressed after his mentor Ted Brautigan is abducted and he is forced to move away from Carol. For a couple of years, he and Carol keep in touch by mail. However, when she stops writing, Bobby goes off the deep end, and becomes a petty criminal. When Pete receives her letter, he becomes at peace with himself and is inspired to keep his scholarship to return for the spring semester. In "Heavenly Shades of Night Are Falling", Bobby has returned to his hometown for the funeral of his childhood best friend. After the funeral, Bobby goes to the park where he, Sully, and Carol had played as kids. Bobby is watching some kids play, and he is approached by an adult Carol. Bobby finds closure after this meeting.
It is often said throughout the book that Pete still thinks of Carol, even thirty years after they were dating, and after he has become married.
Pete's classes at UMO are
English, his best subject as he wants to be a writer
Sociology, a class that most of the freshmen seem to take, including Stoke Jones
Geology, a class he has with Skip
European History, another class that he excels at
It is never stated what his fifth class is, although it is probably some sort of Math class, as he has at least one English, Science (Geology), and Social Studies class (European History, and Sociology)