Ivan is a silverback gorilla born in the wild but currently living in a spacious human-made zoo enclosure. He takes his role as a troop leader seriously and approaches his impending fatherhood with a mixture of quiet confidence and growing anxiety. Having lost his original family to human poachers, he relies heavily on his close-knit circle of animal friends to help him adjust to his new responsibilities.

Bob is a tiny, acorn-brown dog with big ears and strong opinions. A former stray who spent time with Ivan at a rundown arcade zoo, he now lives with a loving human family but frequently visits his old friends at the zoo's Canine Corner. He offers blunt, practical advice to Ivan about parenting based on his observation of humans and his own life.

Kinyani is a female gorilla with thick, bark-colored fur who serves as Ivan's partner and confidant. Unlike Ivan, she has never lived in the wild, though she shares a history of mistreatment by humans before arriving at the zoo. She handles the surprises of pregnancy with a practical, sometimes stern demeanor.

Ruby is a young adult elephant who was rescued from the same arcade zoo as Ivan and Bob. Having grown from a frightened youngster into a responsible member of her herd, she frequently visits Canine Corner. She provides Ivan with a mature perspective on parenting while dealing with a younger calf who constantly shadows her.

Raji is Ivan and Kinyani's daughter, named through a human contest with a word meaning "hope." She possesses boundless physical energy, often running back and forth to practice jumping from rock formations. Her inquisitive and bold attitude frequently keeps Ivan anxious about her safety in the enclosure.

Tuma is Ivan and Kinyani's son, named with a word meaning "hope." He is highly inquisitive and constantly asks Ivan complex questions about how the world works. He admires his father's role as a silverback, going so far as to build small structures out of sticks to practice protecting the troop.

Maya is a zookeeper and Ivan's favorite human caretaker. She strives to keep the gorillas mentally engaged by creating puzzles and mimicking natural foraging methods. Though well-meaning and deeply caring, her hands-on approach to managing the gorilla pregnancy occasionally clashes with Ivan's desire for independence.

Tag was Ivan's twin sister from his early days in the wild. While Ivan was quiet and observant, she was highly energetic and loved to run, earning her name from her favorite game.

Stella was an older elephant who passed away prior to the events of the story. Ivan continues to hold fond memories of her, noting that his grief has transitioned into a comforting mental refuge.