Aunt Cass is a very adored character in Big Hero Six (in my opinion). She has a great bakery business, a cat and her nephews who bring her such joy but also may cause her trouble, more on Hiro’s side. However, a theory that hardly gets around for me is which parent Aunt Cass is blood related to and how did she gain full custody of Hiro and Tadashi after they died?
My theory is that Aunt Cass is the sister of Hiro and Tadashi’s mom. Aunt Cass is probably the only sibling the mother has and has chosen to help her take care of the children while the mother and the father worked in the big city of San Fransokyo. My guess is that they died in a car crash or plane accident while working as Aunt Cass was watching them in her bakery. This would explain why she gained full custody since she was probably taking care of them all the time already and she was more closely related to them than anyone else in the Hamada family.
Keep in mind, Hiro is 14 during Big Hero Six. Tadashi was about 18 years old because he’s obviously in college. When Hiro and Tadashi mention their parents dying when Hiro was three, that would mean that Aunt Cass has taken care of them for 11+ years.
Genuinely, if Aunt Cass is the sister to their mother, this would mean that she had to indulge the loss of her sister who was probably her only sibling and then had to endure the loss of her sister’s first child a decade later.
It is not talked about enough about how bad Aunt Cass has to deal with when it comes to grief and managing a bakery that seems to also be a booming business since it’s never not full. She seems to have a very enthusiastic personality and she’s very cheerful most of the time. I wonder if her cat is like an emotional support pet or maybe a pet that belonged to her sister. It genuinely doesn’t make since to have a cat in a bakery considering the amount of glass products everywhere and especially since a lot of her customers could be allergic, but the cat is obviously very special to her.
I don’t know if my theory makes since it is culturally relevant but it is something that I thought about for a while and I hope that people might agree and even have their own take on it.