Cassandra, nicknamed
Cass, is an 11-year-old girl and one of the two protagonists of the novel. She is a self-proclaimed survivalist and prides herself on her extensive knowledge of various disasters as well as her ubiquitous backpack, which she fills with survival gear. Although she initially prefers to work alone, she befriends Max-Ernest and allows him to accompany her. She is often seen with braided hair but is mostly known for her large, pointy ears. She lives with a single mother and does not know who her father is but is on good terms with her so-called substitute grandfathers. In book three, she finds out that she is adopted.
Max-Ernest is an 11-year-old boy and aspiring comedian. His parents went through their version of a "divorce" shortly after his birth because they couldn't decide whether to name him Max or Ernest. They combined both choices into one name before splitting their house down the middle so that Max-Ernest would still get to live with both parents. He is believed to have some sort of disorder, although what it is remains a mystery. During the course of the book, he makes his first friend: Cass. He ensures that every hair on his head is of equal length, for philosophical reasons: he wants each and every hair treated with equality. He is shown to enjoy riddles, magic, and jokes.
Ms. Mauvais and
Dr. L, the antagonists of the novel, are members of the Midnight Sun, a society devoted to finding the Secret in the hopes of gaining eternal life. Once they find out Cass and Max-Ernest have his notebook, they are willing to go to any lengths to take it from them. It is revealed that Dr. L is Pietro Bergamo's twin brother. He is described as tall with silver hair, tanned skin, and white teeth. Ms. Mauvais's attributes resemble those of a Barbie doll: big eyes, a tiny waist, stylish blonde hair, and gold jewelry. Thus, Pietro refers to her as the Golden Lady; he also notes her icy voice. Ms. Mauvais and Dr. L are much older than they look; they wear
long gloves to hide their wrinkled skin, which only appears on their hands.
Pietro Bergamo is the synesthetic magician who was given The Symphony of Smells by Ms. Mauvais many years ago. Cass and Max-Ernest find his journal whilst exploring his house. He joined the circus with his twin brother Luciano, also synesthetic, before Luciano was sold off to Ms. Mauvais. Although the narrator often refers to him as "dead," Cass and Max-Ernest receive a note from him in code which they decipher. Pietro's initials are used at the end of the note.
Benjamin Blake is a synesthetic boy who goes to Cass and Max-Ernest's school. He became well known for winning an art contest due to his condition's influence on his work. He is kidnapped by Dr. L. and Ms. Mauvais as they believe his brain would help them find information on the Secret. He mumbles to the point of near-unintelligibility.
Grandpa Larry and Grandpa Wayne are Cass's grandfathers. Because her biological grandparents are unknown, Larry and Wayne stepped in as her "substitute" grandparents. Grandpa Larry was Cass' mother's history teacher when she was in high school; while Wayne's relationship with Larry or Cass is not stated, Bosch has confirmed that he is in a relationship with Larry. They own a shop established in an old abandoned fire station known as The Fire Sale, where they live with their blind and nearly deaf dog, Sebastian, dubbed the Seeing-Nose Dog.
Owen is introduced as Cass's butler when she is taken to the Midnight Sun. When they first meet, he has a strong stutter and appears to be shy but friendly. However, he is revealed to be a spy for the Terces society who helps Cass and Max-Ernest escape the Midnight Sun with Benjamin Blake. Owen's most notable characteristic is his predilection for disguises, for which he can drastically alter his appearance and speaking voice.
Amber is Cass's classmate, often called the nicest girl in school and third prettiest; however, she is often shown to be snooty and gossipy. She is a fan of the Skelton Sisters and a consumer of their lip balm line, Smoochies. She receives a new flavor each week and gives the old one away, often to Cass.
Gloria Fortune is a probate specialist or a "real estate agent for the dead." She often finds herself at the Fire Sale delivering items after clearing out homes belonging to the deceased. She loves to gossip and runs into Cass at the Midnight Sun Spa and Sensorium; however, she later has no recollection of her visit to the spa. ==References==