Ivan is the protagonist and point-of-view character of The One and Only Family. As a gorilla, Ivan has always been aware of his size and strength, but it’s not until his twins are born that he realizes that he’s “a four-hundred-pound animal who could destroy…well, a whole lot of things” (122)—including his children if he isn’t careful. Ivan’s realization is a jumping-off point for much of the change that he experiences over the course of the novel. Becoming a parent shifts how Ivan thinks of himself and the world. Things that were once just features of the landscape become potential threats to the safety of the twins, and information he’s always known takes on new meaning because it is completely new to his children.

Through Ivan’s journey, the book explores Universality in Life Experiences. Like humans, Ivan becomes a parent and learns to care for little ones. Applegate draws on human emotion and experience to inform Ivan’s character, aiming to make him relatable to readers of all ages.

Ivan also grapples with his past and the responsibility he holds as the silverback leader of his troop. His challenges are largely informed by his current captivity, as well as the humans of his past.