|“||My dear, I'm a cat. Everything I see is mine.||”|
–Bast, in The Red Pyramid.
When Ra found Sekhmet to be too unruly to be his champion, he replaced her with Bast. As Ra was forced to withdraw into the heavens, he bound Bast and Apophis together and sent them to the Duat so that she would eternally fight him, keeping Apophis from rising. Although Bast was proud to have this duty, she eventually began to realize that Ra had intended for them to kill one another repeatedly, thus weakening each other's essences, until they "ripped each other into nothingness," allowing the world to finally be safe. Bast was eventually freed by Ruby and Julius Kane, who sensed that Bast would be destroyed by Apophis but fail to destroy him, leaving him free to escape his prison.
She is the great cat goddess in Egyptian mythology. As the daughter of the sun god, she was believed to use the sun's power to make crops grow, and was prayed to for good harvest. In the books, however, it is not shown or mentioned that Bast can generate or manipulate flames or solar power. Cats were sacred to Bast, and to harm one was considered to be a severe crime. They were regarded as guardians of the household, protecting the crops and slowing the spread of disease by catching and killing vermin. Bast was worshipped all throughout Ancient Egypt, but her cult was centered in the city of Bubastis in the 18th Nome of Lower Egypt.
After Julius releases Isis, Horus, Set, Nephthys, and Osiris from the Rosetta Stone, Bast, still in cat form as Muffin, travels with Amos Kane, Sadie, and Carter to the Twenty-First Nome, Brooklyn. After an attack by the longnecks, Bast revealed her true identity to Sadie and Carter. Bast also defeated the longnecks. She was able to hold off Serqet in Manhattan long enough for the siblings to escape to the First Nome with Zia Rashid. She later rejoined them in Paris when the siblings went on the run from the House of Life and helped them travel to the Land of the Dead and later to Phoenix. She was forced into the Duat while fighting Sobek at the Rio Grande River, but managed to keep her host, Muffin, from harm. Later, as a gift from the gods, Bast is brought back from the Duat to help Carter and Sadie. Bast also has a knack to penetrate statues.
Bast, along with Carter, Sadie, and Amos Kane, teach magic classes, as well as other classes such as Advanced Cat Grooming, and Napping. According to Carter, there was a waiting list to get into Napping. Bast went back to the Duat to check on Apophis. She told them a friend of hers (Bes) would be coming to watch them. She later told Sadie and Walt as they were travelling to find the final scroll of Ra that Apophis wants them to succeed in their quest. Sadie and Walt still refuse to abandon the quest and proceeded. She later joined them in the battle and afterwards when with Ra (her father) in his sun boat, as well as later when Anubis takes them to visit the gods she is their and it is quoted that "She looked as if she wanted to shred Horus like a scratching post". After Bes sacrificed himself to allow Carter and Sadie to continue, Bast, Carter and Sadie go back to Sunny Acres Assisted-Living Community (a place for old, lost gods) to visit him. Bes is in poor condition, all he does is sit in a wheel chair and stare out the window. Tawaret gets mad at Bast and yells at her that Bes's condition is her fault and that she used him. Bast felt ashamed for this happening to Bes.
Bast continues to help guard Brooklyn House. She is relieved when Sadie, Carter, Walt, and their friends return from Texas alive and refers to them as her "kittens." Later, she goes to help defend the First Nome from Apophis and his followers and takes part in the battle against Apophis fighting him single-handed before help arrives. Bast fights all the way through the battle, holding on even when the other gods are defeated and holds him off long enough for the Kanes to destroy Apophis with the help of the restored Bes.
After Apophis is defeated and the gods distance themselves from the mortal world, Sadie and Carter speak to her outside the House of Rest, where she seems to express some regret about losing Bes to Tawaret. She shows Carter and Sadie an image of Horus taking his throne (much like Carter had done). Bast also explains that she cannot return with them to Brooklyn House because the gods need to stay distant from the mortal world and the kids have grown up enough that they do not need her around all the time, but that she is sure that they will meet again.
Due to a mutual problem of some sort, Chiron has a joint task force meeting with two acquaintances of his from other pantheons. One is described as a cat, Bast, while the other is a severed head, Mimir.
Bast is small and agile, like a gymnast, with black hair, lamp-like yellow eyes, and wears a skin-tight leopard-print leotard. When she smiles, her eyes glint like a cat's and she appears to look either concerned, amused, or both. She, like all gods, can change her appearance at will, although magicians like Carter can see through it, with some initial difficulty.
Although loving and playful, Bast has a serious side to her that surfaces in the face of danger. Bast considers herself a coward for abandoning her duty to fight Apophis and because she will run when frightened. Despite this, Bast has made many self-sacrificing decisions to protect Sadie and Carter, belying her true nature as a brave warrior. She is also very protective, (as she is a goddess of protection), of Carter and especially Sadie e.g. After Horus and Isis had threatened them "she looked as though she wanted to shred Horus like a scratching post".
- Transformation: Bast possesses the ability to transform between human form and that of her host, Muffin. At first she required Sadie calling out to her for help to perform the transformation which she stated took a lot of power, but afterwards she could do it more seamlessly with much less power and without the need to be called upon to transform back to human form.
- Combat Prowess: Bast is an extremely skilled fighter, entangling the necks of two serpopards before cutting their heads off. She displays a great deal of agility in combat as well, performing flips and jumps easily. Bast's prowess allowed her to fight Apophis for millennia in never-ending combat. During the Battle of the First Nome, Bast single-handedly held off Apophis before being joined by Sobek, Ra and Bes. Bast's prowess was such that she battled Apophis without her combat avatar and was one of the last two gods standing, the other being Bes at the end of the battle. Bast uses two knives she can pull out of her sleeves in combat and is very adept at using them.
- Animal Charming: As the goddess of cats, Bast has the ability to communicate with and command cats. In the Red Pyramid, Bast was able to understand what cats were telling her and communicate back, seemingly telepathically as she never spoke a word. With a hum, Bast was also capable of summoning cats to aid her in battle against the carriers.
- Combat Avatar: Bast is capable of summoning a combat avatar of her ancient form: a twenty-foot tall woman with a cat's head. In this form, Bast has deadly claws to rip enemies to pieces.
- Duat Travel: As a creature of the Duat, Bast is able to easily slip into and out of its layers for quick escapes if she's on her own. Even when her magical energy was nearly exhausted, Bast was capable of transforming back into her host and escaping through the Duat.
- Healing: Bast possesses some skill in healing, healing Carter's broken ribs from a criosphinx attack with a spell after saving him and Sadie.
- Banishment: Bast was able to banish Sobek back to the Duat. However, due to the low level of strength she had at the time, she used up all of her life force doing it and died until the other gods resurrected her as a gift to the Kanes.
- Spell Casting: Bast is able to cast some spells such as the one which dialed down the sensitivity of the first part of the Book of Ra so it no longer set the city on fire or was stuck to Sadie's hand.
- Connection with Apophis: As a result of being locked in combat with Apophis for millennia, Bast possesses the ability to read his mind to an extent when in close proximity.
- Possession: As goddess of cats, Bast can possess any living cat as a host, and speak easily communicate through them, though only for a few minutes, likely because her power would consume her hosts.
Ra: Bast is deeply loyal to her master and father, even after she realizes that he had planned for her to die while destroying Apophis.
Apophis: Bast both loathes and fears her mortal enemy, not even willing to speak his name. In The Throne of Fire, Bast finds out that when she gets close enough to the Apophis she can hear his thoughts, probably because she's been fighting him for so long.
Sadie and Carter Kane: Bast holds a deep, motherly affection for her two charges, calling them her 'kittens,' even posing as Carter's aunt in public, causing Carter to call her "Aunt Kitty" (much to her annoyance). She often places their welfare before her own and sacrifices herself in the battle against Sobek to protect them.
Bes: Bes used to have a crush on Bast, but he eventually gave up after realizing that Bast only saw him as a friend. He may still have some feelings left for her. Bast trusts Bes, enough to let him guard Carter and Sadie, and is quite sad to see him in Sunny Acres without his ren.
Tawaret: Tawaret dislikes Bast, probably out of jealousy because of Bes's old crush on Bast. She blames Bast for Bes losing his Ren.
Ruby Kane: When Carter and Sadie's mother Ruby goes to Cleopatra's Needle, she dies and Bast comes out of her cell. After, Bast promises Julius that she would take care of Sadie.
- She is still hosted by Muffin, as her appearance hasn't changed (as it tends to with hosts).
- Although she is the daughter of Ra, she doesn't seem to have power over fire, or doesn't use it.
- Bast used to protect the children of the pharaoh in ancient Egypt, as she protects Carter and Sadie.
- Bast states in The Red Pyramid that her powers are limited in the form of Muffin who is an imperfect host. This indicates that if Bast had a more powerful host, she'd be even more powerful than she was during the books. However, she herself stated that her power against other gods is limited as she is incapable of defeating Set even in a powerful host.
- Bast is acquaintances and possibly friends with Chiron the centaur.
- Bast has behavioral traits akin to a cat. As shown in The Red Pyramid she randomly disconnected and shredded apart a wrecking ball from a crane despite it posing no harm