Mustard Cookie is a very contrarian Cookie. She appears to hate assumptions about her based on her appearance, as well as the assumption that Cookies have to be sweet. She accuses others of bias, and seems to really only have respect for other artists or people she considers "different." She has a very low tolerance for Dr. Wasabi Cookie and her antics, but still seems to care deeply for her because Dr. Wasabi Cookie is her Grandma. She usually tries to turn cookies on her side