Bast enters the story as Sadie Kane’s orange tabby cat, Muffin. When she transforms to her true form, she is a sleek, athletic woman in a leopard print leotard with black hair and yellow cat eyes. She conceals her weapons, twin knives, in her sleeves. With these weapons, she fought Apophis, the serpent of chaos, for millennia before Ruby Kane released her from the Abyss so that she could recover from her near-exhaustion. Fiercely protective of Carter and Sadie, who she calls her kittens, Bast once gave her life for them. The gods rewarded the Kanes for their bravery against Set, the god of evil, by resurrecting her. She can sometimes show cowardice, a catlike aloofness, and self-centeredness, Bast is nonetheless a steadfast and loyal companion. Her avatar is a giant cat-headed woman.