A tortoiseshell's coat blends black-based and orange-based colors in patches or a fine mottle, usually with little or no white. Dilute torties look soft gray and cream, and torbies add tabby stripes. Because the orange gene sits on the X chromosome, almost all are female. In Philly, most you'll see are domestic shorthairs, though the pattern turns up in many breeds.
Their "tortitude" reputation for sass is folklore more than fact. An owner survey reported slightly more aggression in torties, but it rests on owner impressions, so treat it as a caution rather than a rule. A tortie's age, history and socialization matter far more than color. Plan on moderate shedding, regular play, and a typical lifespan of 12 to 18 years.