Callie is very cheerful and excitable, and usually sports a grin on her face. She values her bond with her cousin Marie, with the two having been inseparable since they were young. As children, they enjoyed stargazing and playing tag together. She is particularly attentive to Marie's changes in mood, even noting when the latter wants to drink a latte based on expression alone. When by herself, however, Callie can become upset and prone to overthinking.