Orange is one of Blue's many friends from preschool, a young orange cat owned by a female human named Sam. The character celebrates Hanukkah with Sam, meaning that her owner's family is Jewish.
Orang Kitten is flame orange with a small, triangular, dark pink nose. She has darker whiskers and a desert sand tummy and muzzle, plus several stripes of the same color on her head and tail (3 triangular ones on her head [her ears are located between the stripes], and up to 3 stripes around her tail). She also has a pair of <blacksmall black eyes and eyebrows.
In "Blue's Big Holiday", it is revealed that Orange Kitten is owned by a female human named Sam. In that very episode, she and Sam can be seen celebrating Hanukkah. Though it was probably for demonstrative purposes only, it could be speculated that one, or both of them are of the Jewish faith, or have an interest in Jewish culture.
Orange Kitten was the first cat to appear, others being Green, Blue, Yellow, and Periwinkle.