Genetics
Almost always female: The tortoiseshell pattern results from orange and black genes on the X chromosome. Females have two X chromosomes and can inherit both alleles.
Males are very rare: Males have only one X chromosome, making male tortoiseshells a genetic anomaly.
Calico cats: Calico is essentially tortoiseshell with white patches, due to a white spotting gene.
Personality
Diverse personalities: Like all cats, tortoiseshells have unique personalities influenced by genetics, upbringing, and temperament.
"Tortitude": This humorous term suggests a feisty personality, but it is a generalization.
Appearance
Colors: Classic tortoiseshell features patches of black, orange, and cream.
Variety: Patch distribution and size vary significantly.
Not a breed: Tortoiseshell is a color pattern, not a breed, so they can be Persians, Siamese, domestic shorthairs, and more.
Tortoiseshells can be loving, playful, independent, and strong-willed. Remember, these are generalizations and every cat is unique.