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.
Calico cats are considered true tricolor cats, sporting a coat of three distinct patches of black, red and white. Others consider tortoiseshell cats to be tricolor cats as well; however, their coat patterns do not display the three colors as distinctly as calicos do.