The series is based on the popular New York Times bestselling book series collectively known as The Expanse,  written by Daniel Abraham and Ty Franck (under the pen name James S. A. Corey). Abraham and Franck will be show producers.
A tortoiseshell cat is a coat color where the cat is a molted brown cat with black, reddish, or orange patches. They can also have white paws. Tortoiseshell cats have unique genetics. The vast majority of tortoiseshell cats are female, because two X chromosomes are required to produce black, gold and orange coloring.
Tortoiseshell is not a breed of cat. Rather, the term tortoiseshell refers to a coat color that can be found in many breeds. They do, however, have certain specific characteristics. Tortoiseshells are almost exclusively female, are not the same as calicos and have distinctive personality traits.