* Jacob "Jake" Cross: A quiet and sensitive 10-year-old boy who is struggling to cope with his parents' separation and his own feelings of loneliness. He is a skilled artist and uses his drawings as a way to express himself.
* Anna "Annie" Cross: Jake's younger sister, a bright and inquisitive 7-year-old who is more open and outgoing than her brother. She is fiercely loyal to Jake and tries to cheer him up.
* Leo Cross: Jake and Annie's father, a kind and loving man who is trying his best to navigate the challenges of being a single parent. He is an architect and uses his skills to build a treehouse for his children.
* Helen Cross: Jake and Annie's mother, a free-spirited artist who is struggling to find her own path after the separation. She is often absent and emotionally distant from her children.
While there are other supporting characters in the story, these four are the primary focus of the narrative.