Sunny is a polite, ten-year-old girl from a Pennsylvania suburb who spends August of 1976 visiting her grandfather in Florida. She initially feels isolated in his retirement community and quietly mourns the beach vacation she originally planned to take with her best friend. She naturally avoids conflict and tends to keep her worries to herself, especially her confusion and fear regarding her older brother's behavior back home.

Patrick is Sunny's optimistic grandfather who lives in the Pine Palms retirement community near Vero Beach, Florida. He frequently announces exciting plans for the day that turn out to be mundane errands, such as visiting the post office or buying groceries. He tries hard to make Sunny feel welcome but fails to notice her discomfort with her new surroundings.

Dale is Sunny's older brother who recently graduated from high school. He wears his hair long, dresses in loose jeans or band t-shirts, and consistently breaks his parents' rules regarding curfews and behavior. His rebellious actions and suspected substance use cause significant tension in the Lewin household, casting a shadow over Sunny's summer.

Buzz is a boy around Sunny's age who spends his summer hanging out at the Pine Palms retirement community where his father works. He earns pocket money by hunting for lost golf balls in the water hazards. He is friendly, enthusiastic, and quickly becomes Sunny's constant companion and guide to the world of superheroes.

Deb is Sunny's best friend from her suburban hometown in Pennsylvania. The two girls share typical pre-teen interests like music, magazines, and discussing haircuts. She provides Sunny with a sense of normalcy, though Sunny occasionally struggles to be completely honest with her about the problems at home.

Sunny's mother manages the Lewin household in Pennsylvania and strives to maintain a normal, happy family image. She frequently clashes with Dale over his behavior and choice of friends. She prefers to keep family conflicts quiet, expecting Sunny to adapt to sudden changes without complaining.

Sunny's father is the head of the Lewin household in Pennsylvania. He grows increasingly frustrated and angry with Dale's late arrivals, altered states, and disrespectful attitude. His arguments with Dale often disrupt the peace of the family home.

Buzz's father works as the groundskeeper at the Pine Palms retirement community. He previously worked as a chemist in Cuba before coming to the United States. He is warm and generous, noticing Sunny's interest in comic books and offering to lend her titles from his personal collection.

Teezy is an elderly resident of Pine Palms who lives upstairs from Patrick. She wears old-fashioned long skirts and warmly welcomes Sunny to the community, presenting her with a homemade Barbie-doll toilet paper cover. She frequently joins her friends for early-bird specials at the local buffet.

Ethel is another elderly resident of the retirement community and a close companion to Teezy. She frequently joins Patrick and Sunny for meals and enthusiastically encourages Sunny to pile her plate high with different foods at the local restaurant.

Sal is a notoriously grumpy resident of the Pine Palms retirement community. He strictly enforces the community rules, blowing a whistle at Sunny and demanding to see her visitor pass when she tries to enter the swimming pool. Despite his harsh exterior, he relies on his neighbors when emergencies arise.

Myra is a 98-year-old resident of Pine Palms who experiences dementia. She occasionally becomes confused about her surroundings and wanders away from her home, believing she is back in New Jersey waiting for a bus to Hoboken.