Claire McKenzie is a high schooler living on Hackett, an island off the coast of the northeastern United States. She befriends Lani, a mysterious New Transfer Student who is despised by the popular kids, including Claire's other friends.
What Happened to Lani Garver contains examples of:
- The Alcoholic: Claire had leukemia in junior high. Ever since that time, her mom has gotten blackout drunk almost every night.
- Ambiguous Gender Identity: Early in the book, Macy asks Lani if he's a girl. He answers, "Oh! No. Not a girl. Sorry." After that Claire thinks of him as a boy, but she notes that he never actually said he was a boy.
- Bathroom Stall of Overheard Insults: During Claire's second week of high school, she was in the bathroom and overheard Eli Spellings call her "that leukemia girl" and say, "Remember her from January? She looked like she'd been nuked in a microwave. Was that sickening or what?" Macy Matlock, the popular girl, made Eli apologize to Claire. That's how Macy and Claire became best friends.
- Boomerang Bigot: Tony Clementi sexually assaults Lani and makes harassing phone calls to him, but is loudly homophobic in front of everyone else. He beats up Lani and says it's because Lani came on to him.
- Buses Are for Freaks: Claire's mom believes in this trope so strongly that Claire is forbidden from ever riding a bus.
- Dude Looks Like a Lady: Lani has feminine facial features, a girly haircut, and a voice that's barely deep enough to be recognizably male. When he first arrives at school, the other kids can't figure out if he's a boy or a girl.
- Foregone Conclusion: The first chapter says that Lani will be murdered.
- Genius Book Club: Lani has spent a lot of time in libraries, since the worst bullies don't go in there. He's read Einstein, Marx, Darwin, Freud, and Hegel.
- Girl Posse: At the beginning of the book, Claire is part of a girl posse consisting of her, Macy, Eli, Myra Whitehall, and Geneva Graham.
- Homeschooled Kids: Claire was homeschooled during seventh grade and part of eighth grade, when she had leukemia and was going through chemotherapy.
- Meaningful Rename: Lani's name was originally spelled Lonny, but he changed it to be more androgynous.
- Nostalgic Narrator: The first chapter is in the present tense and takes place months after Lani's murder. The rest of the book is in the past tense.
- Really Moves Around: Lani's dad was in the military. He's moved almost every year since fifth grade.
- The Runaway: Lani ran away from the small town where he was previously living and lived on the streets of Philadelphia for two years. During that time he attended Creative and Performing Arts High School of Philadelphia, the first school he attended where he made friends instead of being bullied for being effeminate.
- Skipping School: Claire starts to feel weak and dizzy and worries that her leukemia is coming back. She doesn't want to talk to her mom about it for fear that it'll make her drink more, so Lani talks her into cutting school, taking a bus to Philadelphia, and getting her blood tested at a charity clinic that mostly treats homeless kids. It turns out that her blood is fine, and her problems are caused by excessive dieting.
- Why Couldn't You Be Different?: Before Lani's parents got divorced, his dad beat him for playing dress-up. The school board blamed his parents for raising a "gender confused" child, so his dad took him to a drill sergeant, a priest, and a psychologist to try to force him to act more manly.
