A 12-year-old girl from New York with a love for research and organization, who lives with her father. Initially focused on her differences from Bett, she eventually forms a close friendship with her.

Bett's biological father and a builder with a penchant for spontaneity and outdoor activities. He resides with Bett in California and has a strong bond with her due to their shared experiences and personalities.

Avery's father and a professional architect in New York known for his formal manner and aversion to taking risks. Initially resistant to change, he reevaluates his views due to his daughter's adventures.

Bett's grandmother who lives in Texas and is known for her theatrical nature, generosity, and inability to keep secrets. She forms a bond with Avery and provides wisdom and support to both girls.

A playwright and Avery's mother, known for her impulsive nature and profound insights. She reconnects with Avery during the summer and forms strong ties with both girls.

A ballet dancer and friend of Kristina who becomes an important support figure during a trip. Known for his humor, cooking skills, and maturity, he plays a key role in helping the families.

The doorman at the apartment building where Gaga and Kristina live, who is known for his good nature and love for theater. He quickly forms a friendship with Gaga through their shared interests.